Internet DRAFT - draft-ietf-trill-rfc7180bis
draft-ietf-trill-rfc7180bis
TRILL Working Group Donald Eastlake
INTERNET-DRAFT Mingui Zhang
Intended status: Proposed Standard Huawei
Obsoletes: 7180 Radia Perlman
Updates: 6325, 7177, 7179 EMC
Ayan Banerjee
Cisco
Anoop Ghanwani
Dell
Sujay Gupta
IP Infusion
Expires: May 1, 2016 November 2, 2015
TRILL: Clarifications, Corrections, and Updates
<draft-ietf-trill-rfc7180bis-07.txt>
Abstract
Since publication of the TRILL (Transparent Interconnection of Lots
of Links) base protocol in 2011, active development and deployment of
TRILL has revealed errata in RFC 6325 and areas that could use
clarifications or updates. RFCs 7177, 7357, and draft-eastlake-trill-
rfc6439bis provide clarifications and updates with respect to
Adjacency, the TRILL ESADI (End Station Address Distribution
Information) protocol, and Appointed Forwarders respectively. This
document provides other known clarifications, corrections, and
updates. It obsoletes RFC 7180 (the previous TRILL clarifications,
corrections, and updates RFC), updates RFC 7177, updates RFC 7179,
and updates RFC 6325.
Status of This Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
Distribution of this document is unlimited. Comments should be sent
to the TRILL working group mailing list: <trill@ietf.org>.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
D. Eastlake, et al [Page 1]
INTERNET-DRAFT TRILL: Clarifications, Corrections, and Updates
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html. The list of Internet-Draft
Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
D. Eastlake, et al [Page 2]
INTERNET-DRAFT TRILL: Clarifications, Corrections, and Updates
Table of Contents
1. Introduction (Changed)..................................5
1.1 Precedence (Changed)...................................5
1.2 Changes That Are Not Backward Compatible (Unchanged)...6
1.3 Terminology and Acronyms (Changed).....................6
2. Overloaded and/or Unreachable RBridges (Unchanged)......8
2.1 Reachability...........................................8
2.2 Distribution Trees.....................................9
2.3 Overloaded Receipt of TRILL Data Packets...............9
2.3.1 Known Unicast Receipt...............................10
2.3.2 Multi-Destination Receipt...........................10
2.4 Overloaded Origination of TRILL Data Packets..........10
2.4.1 Known Unicast Origination...........................10
2.4.2 Multi-Destination Origination.......................11
2.4.2.1 An Example Network................................11
2.4.2.2 Indicating OOMF Support...........................12
2.4.2.3 Using OOMF Service................................12
3. Distribution Trees and RPF Check (Changed).............14
3.1 Number of Distribution Trees (Unchanged)..............14
3.2 Distribution Tree Update Clarification (Unchanged)....14
3.3 Multicast Pruning Based on IP Address (Unchanged).....14
3.4 Numbering of Distribution Trees (Unchanged)...........15
3.5 Link Cost Directionality (Unchanged)..................15
3.6 Alternative RPF Check (New)...........................15
3.6.1 Example of the Potential Problem....................16
3.6.2 Solution and Discussion.............................17
4. Nicknames Selection (Unchanged)........................19
5. MTU (Maximum Transmission Unit) (Unchanged)............21
5.1 MTU-Related Errata in RFC 6325........................21
5.1.1 MTU PDU Addressing..................................21
5.1.2 MTU PDU Processing..................................22
5.1.3 MTU Testing.........................................22
5.2 Ethernet MTU Values...................................22
6. TRILL Port Modes (Unchanged)...........................24
7. The CFI/DEI Bit (Unchanged)............................25
8. Other IS-IS Considerations (Changed)...................26
8.1 E-L1FS Support (New)..................................26
8.1.1 Backward Compatibility..............................26
8.1.2 E-L1FS Use for Existing (sub)TLVs...................27
8.2 Control Packet Priorities (New).......................28
8.3 Unknown PDUs (New)....................................29
8.4 Nickname Flags APPsub-TLV (New).......................29
8.5 Graceful Restart (Unchanged)..........................31
8.6 Purge Originator Identification (New).................31
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Table of Contents (continued)
9. Updates to [RFC7177] (Adjacency) (Changed).............32
10. TRILL Header Update (New).............................33
10.1 Color Bit............................................34
10.2 Flag Word Changes (update to [RFC7179])..............34
10.2.1 Extended Hop Count.................................34
10.2.1.1 Advertising Support..............................34
10.2.1.2 Ingress Behavior.................................35
10.2.1.3 Transit Behavior.................................35
10.2.1.4 Egress Behavior..................................36
10.2.2 Extended Color Field...............................36
10.3 Updated Flag Word Summary............................36
11. Appointed Forwarder Status Lost Counter (New).........38
12. IANA Considerations (Changed).........................39
12.1 Previously Completed IANA Actions (Unchanged)........39
12.2 New IANA Actions (New)...............................39
12.2.1 Reference Updated..................................39
12.2.2 The 'E' Capability Bit.............................40
12.2.3 NickFlags APPsub-TLV Number and Registry...........40
12.2.4 Updated TRILL Extended Header Flags................40
12.2.5 TRILL-VER Sub-TLV Capability Flags.................41
12.2.6 Example Nicknames..................................41
13. Security Considerations (Changed).....................42
Normative References......................................43
Informative References....................................44
Acknowledgements..........................................46
Appendix A: Life Cycle of a TRILL Switch Port (New).......47
Appendix B: Example TRILL PDUs (New)......................50
B.1 LAN Hello over Ethernet...............................50
B.2 LSP Over PPP..........................................51
B.3 TRILL Data Over Ethernet..............................52
B.4 TRILL Data Over PPP...................................53
Appendix C: Changes to Previous RFCs (New)................55
C.1 Changes to Obsoleted [RFC7180]........................55
C.1.1 Changes.............................................55
C.1.2 Additions...........................................55
C.1.3 Deletions...........................................56
C.2 Changes to [RFC6325]..................................57
C.3 Changes to [RFC7177]..................................57
C.4 Changes to [RFC7179]..................................57
Appendix Z: Change History................................58
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1. Introduction (Changed)
Since the TRILL base protocol [RFC6325] was published in 2011, active
development and deployment of TRILL has revealed errors in the
specification [RFC6325] and several areas that could use
clarifications or updates.
[RFC7177], [RFC7357], and [rfc6439bis] provide clarifications and
updates with respect to Adjacency, the TRILL ESADI (End Station
Address Distribution Information) protocol, and Appointed Forwarders
respectively. This document provides other known clarifications,
corrections, and updates to [RFC6325], [RFC7177], and [RFC7179]. This
document obsoletes [RFC7180], the previous TRILL clarifications,
corrections, and updates document, updates [RFC6325], updates
[RFC7177] as described in Section 9, and updates [rfc7179] as
described in Section 10.2 and 10.3. The charges to these RFCs are
summarized in Appendix C.
Sections of this document are annotated as to whether they are "New"
technical material, material that has been technically "Changed", or
material that is technically "Unchanged", by the appearance of one of
these three words in parenthesis at the end of the section header. A
section with only editorial changes is annotated as "(Unchanged)". If
no such notation appears, then the first notation encountered on
going to successively higher-level headers (those with shorter
numbers) applies. Appendix C describes changes, summarizes material
added, and lists material deleted.
1.1 Precedence (Changed)
In case of conflict between this document and [RFC6325], [RFC7177],
or [RFC7179] this document takes precedence.
In addition, Section 1.2 (Normative Content and Precedence) of
[RFC6325] is updated to provide a more complete precedence ordering
of the sections of [RFC6325] as show below, where sections to the
left take precedence over sections to their right. There are no known
conflicts between these sections but Sections 1 and 2 are less
detailed and do not mention every corner case while later sections of
[RFC6325] are more detailed. This precedence is specified as a fall
back in case some conflict is found in the future.
4 > 3 > 7 > 5 > 2 > 6 > 1
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1.2 Changes That Are Not Backward Compatible (Unchanged)
The change made by Section 3.4 below, which was also present in
[RFC7180], is not backward compatible with [RFC6325] but has
nevertheless been adopted to reduce distribution tree changes
resulting from topology changes.
The several other changes herein that are fixes to errata for
[RFC6325] -- [Err3002] [Err3003] [Err3004] [Err3052] [Err3053]
[Err3508] -- may not be backward compatible with previous
implementations that conformed to errors in the specification.
1.3 Terminology and Acronyms (Changed)
This document uses the acronyms defined in [RFC6325], some of which
are repeated below for convenience, along with some additional
acronyms and terms as follows:
Campus - a TRILL network consisting of TRILL switches, links, and
possibly bridges bounded by end stations and IP routers. For
TRILL, there is no "academic" implication in the name "campus".
CFI - Canonical Format Indicator [802].
DEI - Drop Eligibility Indicator [802.1Q-2014].
FGL - Fine Grained Labeling [RFC7172]
OOMF - Overload Originated Multi-destination Frame.
PDU - Protocol Data Unit.
RBridge - Routing Bridge, an alternative name for a TRILL Switch.
RPFC - Reverse Path Forwarding Check.
SNPA - SubNetwork Point of Attachment (for example, MAC address).
TRILL - Transparent Interconnection of Lots of Links or Tunneled
Routing in the Link Layer.
TRILL Switch - A device implementing the TRILL protocol. An
alternative name for an RBridge.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
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In this document a "packet" usually refers to a TRILL Data packet or
TRILL IS-IS packet received from or sent to a TRILL switch while a
"frame" usually refers to a native frame being received from or sent
to an end station. (The word frame also occurs in other contexts such
as the "Frame Check Sequence" that is at the end of Ethernet
transmissions.)
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2. Overloaded and/or Unreachable RBridges (Unchanged)
In this Section 2, the term "neighbor" refers only to actual RBridges
and ignores pseudonodes.
RBridges may be in overload as indicated by the [IS-IS] overload flag
in their LSPs (Link State PDUs). This means that either (1) they are
incapable of holding the entire link-state database and thus do not
have a view of the entire topology or (2) they have been configured
to have the overload bit set. Although networks should be engineered
to avoid actual link-state overload, it might occur under various
circumstances. For example, if a very large campus included one or
more low-end TRILL Switches.
It is a common operational practice to set the overload bit in an
[IS-IS] router (such as a TRILL Switch) when performing maintenance
on that router that might affect its ability to correctly forward
packets; this will usually leave the router reachable for maintenance
traffic, but transit traffic will not be routed through it. (Also,
in some cases, TRILL provides for setting the overload bit in the
pseudonode of a link to stop TRILL Data traffic on an access link
(see Section 4.9.1 of [RFC6325]).)
[IS-IS] and TRILL make a reasonable effort to do what they can even
if some TRILL Switches/routers are in overload. They can do
reasonably well if a few scattered nodes are in overload. However,
actual least-cost paths are no longer assured if any TRILL Switches
are in overload.
For the effect of overload on the appointment of forwarders, see
[rfc6439bis].
2.1 Reachability
Packets are not least-cost routed through an overloaded TRILL Switch,
although they may originate or terminate at an overloaded TRILL
Switch. In addition, packets will not be least-cost routed over
links with cost 2**24 - 1 [RFC5305]; such links are reserved for
traffic- engineered packets, the handling of which is beyond the
scope of this document.
As a result, a portion of the campus may be unreachable for least-
cost routed TRILL Data because all paths to it would be through
either a link with cost 2**24 - 1 or through an overloaded RBridge.
For example, an RBridge (TRILL Switch) RB1 is not reachable by TRILL
Data if all of its neighbors are connected to RB1 by links with cost
2**24 - 1. Such RBridges are called "data unreachable".
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The link-state database at an RBridge, for example RB1, can also
contain information on TRILL Switches that are unreachable by IS-IS
link-state flooding due to link or RBridge failures. When such
failures partition the campus, the TRILL Switches adjacent to the
failure and on the same side of the failure as RB1 will update their
LSPs to show the lack of connectivity, and RB1 will receive those
updates. As a result, RB1 will be aware of the partition. Nodes on
the far side of the partition are both IS-IS unreachable and data
unreachable from RB1. However, LSPs held by RB1 for TRILL Switches
on the far side of the failure will not be updated and may stay
around until they time out, which could be tens of minutes or longer.
(The default in [IS-IS] is twenty minutes.)
2.2 Distribution Trees
An RBridge in overload cannot be trusted to correctly calculate
distribution trees or correctly perform the RPFC (Reverse-Path
Forwarding Check). Therefore, it cannot be trusted to forward multi-
destination TRILL Data packets. It can only appear as a leaf node in
a TRILL multi-destination distribution tree. Furthermore, if all the
immediate neighbors of an RBridge are overloaded, then it is omitted
from all trees in the campus and is unreachable by multi-destination
packets.
When an RBridge determines what nicknames to use as the roots of the
distribution trees it calculates, it MUST ignore all nicknames held
by TRILL Switches that are in overload or are data unreachable. When
calculating RPFCs for multi-destination packets, an RBridge, such as
RB1 MAY, to avoid calculating unnecessary RPFC state information,
ignore any trees that cannot reach to RB1 even if other RBridges list
those trees as trees that other TRILL Switches might use. (But see
Section 3.)
2.3 Overloaded Receipt of TRILL Data Packets
The receipt of TRILL Data packets by overloaded RBridge RB2 is
discussed in the subsections below. In all cases, the normal Hop
Count decrement is performed, and the TRILL Data packets are
discarded if the result is less than one or if the egress nickname is
illegal.
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2.3.1 Known Unicast Receipt
RB2 will not usually receive unicast TRILL Data packets unless it is
the egress, in which case it egresses and delivers the data normally.
If RB2 receives a unicast TRILL Data packet for which it is not the
egress, perhaps because a neighbor does not yet know it is in
overload, RB2 MUST NOT discard the packet because the egress is an
unknown nickname as it might not know about all nicknames due to its
overloaded condition. If any neighbor, other than the neighbor from
which it received the packet, is not overloaded, it MUST attempt to
forward the packet to one of those neighbors selected at random
[RFC4086]. If there is no such neighbor, the packet is discarded.
2.3.2 Multi-Destination Receipt
If RB2 in overload receives a multi-destination TRILL Data packet,
RB2 MUST NOT apply an RPFC since, due to overload, it might not do so
correctly. RB2 egresses and delivers the frame locally where it is
Appointed Forwarder for the frame's VLAN (or, if the packet is FGL,
for the VLAN that FGL maps to at the port), subject to any multicast
pruning. But since, as stated above, RB2 can only be the leaf of a
distribution tree, it MUST NOT forward a multi-destination TRILL Data
packet (except as an egressed native frame where RB2 is Appointed
Forwarder).
2.4 Overloaded Origination of TRILL Data Packets
Overloaded origination of unicast TRILL Data packets with known
egress and of multi-destination packets is discussed in the
subsections below.
2.4.1 Known Unicast Origination
When RB2, an overloaded RBridge, ingresses or creates a known
destination unicast data packet, it delivers it locally if the
destination is local. Otherwise, RB2 unicasts it to any neighbor
TRILL Switch that is not overloaded. It MAY use what routing
information it has to help select the neighbor.
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2.4.2 Multi-Destination Origination
Overloaded RBridge RB2 ingressing or creating a multi-destination
data packet is more complex than for the known unicast case as
discussed below.
2.4.2.1 An Example Network
For example, consider the network below in which, for simplicity, end
stations and any bridges are not shown. There is one distribution
tree of which RB4 is the root, as represented by double lines. Only
RBridge RB2 is overloaded.
+-----+ +-----+ +-----+ +-----+
| RB7 +====+ RB5 +=====+ RB3 +=====+ RB1 |
+-----+ +--+--+ +-++--+ +--+--|
| || |
+---+---+ || |
+------+RB2(ov)|======++ |
| +-------+ || |
| || |
+--+--+ +-----+ ++==++=++ +--+--+
| RB8 +====+ RB6 +===++ RB4 ++=====+ RB9 |
+-----+ +-----+ ++=====++ +-----+
Since RB2 is overloaded, it does not know what the distribution tree
or trees are for the network. Thus, there is no way it can provide
normal TRILL Data service for multi-destination native frames. So
RB2 tunnels the frame in a TRILL Data packet to a neighbor that is
not overloaded if it has such a neighbor that has signaled that it is
willing to offer this service. RBridges indicate this in their
Hellos as described below. This service is called OOMF (Overload
Originated Multi- destination Frame) service.
- The multi-destination frame MUST NOT be locally distributed in
native form at RB2 because this would cause the frame to be
delivered twice. Instead it is tunneling to a neighbor as provided
in this section. For example, if RB2 locally distributed a
multicast native frame and then tunneled it to RB5, RB2 would get
a copy of the frame when RB3 transmitted it as a TRILL Data packet
on the multi-access RB2-RB3-RB4 link. Since RB2 would, in
general, not be able to tell that this was a frame it had tunneled
for distribution, RB2 would decapsulate it and locally distribute
it a second time.
- On the other hand, if there is no neighbor of RB2 offering RB2 the
OOMF service, RB2 cannot tunnel the frame to a neighbor. In this
case, RB2 MUST locally distribute the frame where it is Appointed
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Forwarder for the frame's VLAN and optionally subject to multicast
pruning.
2.4.2.2 Indicating OOMF Support
An RBridge RB3 indicates its willingness to offer the OOMF service to
RB2 in the TRILL Neighbor TLV in RB3's TRILL Hellos by setting a bit
associated with the SNPA (SubNetwork Point of Attachment, also known
as MAC address) of RB2 on the link (see IANA Considerations).
Overloaded RBridge RB2 can only distribute multi-destination TRILL
Data packets to the campus if a neighbor of RB2 not in overload
offers RB2 the OOMF service. If RB2 does not have OOMF service
available to it, RB2 can still receive multi-destination packets from
non-overloaded neighbors and, if RB2 should originate or ingress such
a frame, it distributes it locally in native form.
2.4.2.3 Using OOMF Service
If RB2 sees this OOMF (Overload Originated Multi-destination Frame)
service advertised for it by any of its neighbors on any link to
which RB2 connects, it selects one such neighbor by a means beyond
the scope of this document. Assuming RB2 selects RB3 to handle
multi-destination packets it originates, RB2 MUST advertise in its
LSP that it might use any of the distribution trees that RB3
advertises so that the RPFC will work in the rest of the campus.
Thus, notwithstanding its overloaded state, RB2 MUST retain this
information from RB3 LSPs, which it will receive as it is directly
connected to RB3.
RB2 then encapsulates such frames as TRILL Data packets to RB3 as
follows: M bit = 0, Hop Count = 2, ingress nickname = a nickname held
by RB2, and, since RB2 cannot tell what distribution tree RB3 will
use, egress nickname = a special nickname indicating an OOMF packet
(see IANA Considerations). RB2 then unicasts this TRILL Data packet
to RB3. (Implementation of Item 4 in Section 4 below provides
reasonable assurance that, notwithstanding its overloaded state, the
ingress nickname used by RB2 will be unique within at least the
portion of the campus that is IS-IS reachable from RB2.)
On receipt of such a packet, RB3 does the following:
- changes the Egress Nickname field to designate a distribution tree
that RB3 normally uses,
- sets the M bit to one,
- changes the Hop Count to the value it would normally use if it
were the ingress, and
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- forwards the TRILL Data packet on that tree.
RB3 MAY rate limit the number of packets for which it is providing
this service by discarding some such packets from RB2. The provision
of even limited bandwidth for OOMFs by RB3, perhaps via the slow
path, may be important to the bootstrapping of services at RB2 or at
end stations connected to RB2, such as supporting DHCP and ARP/ND
(Address Resolution Protocol / Neighbor Discovery). (Everyone
sometimes needs a little OOMF (pronounced "oomph") to get off the
ground.)
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3. Distribution Trees and RPF Check (Changed)
Two corrections, a clarification, and two updates related to
distribution trees appear in the subsections below along with an
alternative, stronger RPF (Reverse Path Forwarding) Check. See also
Section 2.2.
3.1 Number of Distribution Trees (Unchanged)
In [RFC6325], Section 4.5.2, page 56, Point 2, 4th paragraph, the
parenthetical "(up to the maximum of {j,k})" is incorrect [Err3052].
It should read "(up to k if j is zero or the minimum of (j, k) if j
is non-zero)".
3.2 Distribution Tree Update Clarification (Unchanged)
When a link-state database change causes a change in the distribution
tree(s), there are several possibilities. If a tree root remains a
tree root but the tree changes, then local forwarding and RPFC
entries for that tree should be updated as soon as practical.
Similarly, if a new nickname becomes a tree root, forwarding and RPFC
entries for the new tree should be installed as soon as practical.
However, if a nickname ceases to be a tree root and there is
sufficient room in local tables, the forwarding and RPFC entries for
the former tree MAY be retained so that any multi-destination TRILL
Data packets already in flight on that tree have a higher probability
of being delivered.
3.3 Multicast Pruning Based on IP Address (Unchanged)
The TRILL base protocol specification [RFC6325] provides for and
recommends the pruning of multi-destination packet distribution trees
based on the location of IP multicast routers and listeners; however,
multicast listening is identified by derived MAC addresses as
communicated in the Group MAC Address sub-TLV [RFC7176].
TRILL Switches MAY communicate multicast listeners and prune
distribution trees based on the actual IPv4 or IPv6 multicast
addresses involved. Additional Group Address sub-TLVs are provided
in [RFC7176] to carry this information. A TRILL Switch that is only
capable of pruning based on derived MAC address SHOULD calculate and
use such derived MAC addresses from the multicast listener IPv4/IPv6
address information it receives.
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3.4 Numbering of Distribution Trees (Unchanged)
Section 4.5.1 of [RFC6325] specifies that, when building distribution
tree number j, node (RBridge) N that has multiple possible parents in
the tree is attached to possible parent number j mod p. Trees are
numbered starting with 1, but possible parents are numbered starting
with 0. As a result, if there are two trees and two possible
parents, in tree 1, parent 1 will be selected, and in tree 2, parent
0 will be selected.
This is changed so that the selected parent MUST be (j-1) mod p. As
a result, in the case above, tree 1 will select parent 0, and tree 2
will select parent 1. This change is not backward compatible with
[RFC6325]. If all RBridges in a campus do not determine distribution
trees in the same way, then for most topologies, the RPFC will drop
many multi-destination packets before they have been properly
delivered.
3.5 Link Cost Directionality (Unchanged)
Distribution tree construction, like other least-cost aspects of
TRILL, works even if link costs are asymmetric, so the cost of the
hop from RB1 to RB2 is different from the cost of the hop from RB2 to
RB1. However, it is essential that all RBridges calculate the same
distribution trees, and thus, all must either use the cost away from
the tree root or the cost towards the tree root. As corrected in
[Err3508], the text in Section 4.5.1 of [RFC6325] is incorrect. It
says:
In other words, the set of potential parents for N, for the tree
rooted at R, consists of those that give equally minimal cost
paths from N to R and ...
but the text should say "from R to N":
In other words, the set of potential parents for N, for the tree
rooted at R, consists of those that give equally minimal cost
paths from R to N and ...
3.6 Alternative RPF Check (New)
[RFC6325] mandates a Reverse Path Forwarding (RPF) Check on multi-
destination TRILL Data packets to avoid possible multiplication
and/or looping of multi-destination traffic during TRILL campus
topology transients. This check is logically performed at each TRILL
switch input port and determines whether it is arriving on the
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expected port based on where the packet started (the ingress
nickname) and the tree on which it is being distributed. If not, the
packet is silently discarded. This check is fine for point-to-point
links; however, there are rare circumstances involving multi-access
("broadcast") links where a packet can be duplicated despite this RPF
Check and other checks performed by TRILL.
Section 3.6.1 gives an example of the potential problem and Section
3.6.2 specifies a solution. This solution is an alternative, stronger
RPF Check that TRILL Switches can be implemented in place of the RFF
Check in [RFC6325].
3.6.1 Example of the Potential Problem
Consider this network:
F--A--B--C--o--D
|
E
All the links except the link between C, D, and E are point-to-point
links. C, D, and E are connected over a broadcast link represented
by the pseudonode "o". For example, they could be connected by a
bridged LAN. (Bridged LANs are transparent to TRILL.)
Although the choice of root is unimportant here, assume that D or F
is chosen as the root of a distribution tree so it is obvious the
tree looks just like the diagram above.
Now assume a link comes up from A to the same bridged LAN. The
network then looks like this:
+--------+
| |
F--A--B--C--o--D
|
E
Let's say the resulting tree in steady state includes all links
except the B-C link. After the network has converged, a packet that
starts from F will go F->A. Then A will send one copy on the A-B link
and another copy into the bridge LAN from which it will be received
by C and D.
Now consider a transition stage where A and D have acted on the new
LSPs and programmed their forwarding plane, while B and C have not
yet done so. This means that B and C both consider the link between
them to still be part of the tree. In this case, a packet that starts
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out from F and reaches A will be copied by A into the A-B link and to
the bridge LAN. D's RPF check says to accept packets on this tree
coming from F over its port on the bridged LAN, so it gets accepted.
D is also adjacent to A on the tree, so the tree adjacency check, a
separate check mandated by [RFC6325] also passes.
However, the packet that gets to B gets sent out by B to C. C's RPF
check still has the old state, and it thinks the packet is OK. C
sends the packet along the old tree, which is into the bridge LAN. D
receives one more packet, but the tree adjacency check passes at D
because C is adjacent to D in the new tree as well. The RPF Check
also passes at D because D's port on the bridged LAN is OK for
receiving packets from F.
So, during this transient state, D gets duplicates of every multi-
destination packet ingressed at F (unless the packet gets pruned)
until B and C act on the new LSPs and program their forwarding
tables.
3.6.2 Solution and Discussion
The problem stems from the RPF Check in [RFC6325] depending only on
the port at which a TRILL Data packet is received, the ingress
nickname, and the tree being used, that is, a check if {ingress
nickname, tree, input port} is a valid combination according to the
receiving TRILL switch's view of the campus topology. A multi-access
link actually has multiple adjacencies overlaid on one physical link
and to avoid the problem shown in Section 3.6.1, a stronger check is
needed that includes the Layer 2 source address of the TRILL Data
packet being received. (TRILL is a Layer 3 protocol and TRILL
switches are true routers that logically strip the Layer 2 header
from any arriving TRILL Data packets and add the appropriate new
Layer 2 header to any outgoing TRILL Data packet to get it to the
next TRILL switch, so the Layer 2 source address in a TRILL Data
packet identifies the immediately previous TRILL Switch that
forwarded the packet.)
What is needed, instead of checking the validity of the triplet
{ingress nickname, tree, input port} is to check that the quadruplet
{ingress nickname, source SNPA, tree, input port} is valid (where
"source SNPA" (Sub-Network Point of Access) is the Outer.MacSA for an
Ethernet link). Although it is true that [RFC6325] also requires a
check that a multi-destination TRILL Data packet is from a TRILL
switch that is adjacent in the distribution tree being used, this is
a separate check from the RPF Check and these two independent checks
are not as powerful as the single unified check for a valid
quadruplet.
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_______
/ \
RB1 ------ o ----- RB2
\_______/
However, this stronger RPF Check is not without cost. In the simple
case of a multi-access link where each TRILL switch has only one port
on the link, it merely increases the size of validity entries by
adding the source SNPA (Outer.MacSA). However, assume some TRILL
Switch RB1 has multiple ports attached to a multi-access link. In the
figure above, RB1 is show with three ports on the multi-access link.
RB1 is permitted to load split multi-destination traffic it is
sending into the multi-access link across those ports (Section 4.4.4
[RFC6325]). Assume RB2 is another TRILL Switch on the link and RB2
is distribution tree adjacent to RB1. The number of validity
quadruplets at RB2 for ingress nicknames whose multi-destination
traffic would arrive through RB1 is multiplied by the number of ports
RB1 has on the access-link because RB2 has to accept such traffic
from any of such ports. Although such instances seem to be very rare
in practice, the number of ports an RBridge has on a link could in
principle be tens or even a hundred or more ports, vastly increasing
the RPF check state at RB2 when this stronger RPF check is used.
Another potential cost of the stronger RPF Check is increased
transient loss of multi-destination TRILL Data packets during a
topology change. For TRILL switch D, the new stronger RPF Check is
(tree->A, Outer.MacSA=A, ingress=A, arrival port=if1) while the old
one was ( tree->A, Outer.MacSA=C, ingress=A, arrival port=if1).
Suppose both A and B have switched to the new tree for multicast
forwarding while D has not updated its RPF Check yet, then the
multicast packet will be dropped at D's input port since D still
expects packet from "Outer.MacSA=C". But we do not have this packet
loss issue if the weaker triplet check (tree->A, ingress=A, arrival
port=if1) is used. Thus, the stronger check can increase the RPF
Check discard of multi-destination packets during topology
transients.
Because of these potential costs, implementation of this stronger RPF
Check is optional. The TRILL base protocol is updated to provide that
TRILL Switches MUST, for multi-destination packets, either implement
the RPF and other checks in [RFC6325] or implement this stronger RPF
Check as a substitute for the [RFC6325] RPF and tree adjacency
checks. There is no problem with a campus having a mixture of TRILL
switches some of which implement one of these RPF checks and some of
which implement the other.
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4. Nicknames Selection (Unchanged)
Nickname selection is covered by Section 3.7.3 of [RFC6325].
However, the following should be noted:
1. The second sentence in the second bullet item in Section 3.7.3 of
[RFC6325] on page 25 is erroneous [Err3002] and is corrected as
follows:
o The occurrence of "IS-IS ID (LAN ID)" is replaced with
"priority".
o The occurrence of "IS-IS System ID" is replaced with "seven-
byte IS-IS ID (LAN ID)".
The resulting corrected sentence in [RFC6325] reads as follows:
"If RB1 chooses nickname x, and RB1 discovers, through receipt
of an LSP for RB2 at any later time, that RB2 has also chosen
x, then the RBridge or pseudonode with the numerically higher
priority keeps the nickname, or if there is a tie in priority,
the RBridge with the numerically higher seven-byte IS-IS ID
(LAN ID) keeps the nickname, and the other RBridge MUST select
a new nickname."
2. In examining the link-state database for nickname conflicts,
nicknames held by IS-IS unreachable TRILL Switches MUST be
ignored, but nicknames held by IS-IS reachable TRILL Switches MUST
NOT be ignored even if they are data unreachable.
3. An RBridge may need to select a new nickname, either initially
because it has none or because of a conflict. When doing so, the
RBridge MUST consider as available all nicknames that do not
appear in its link-state database or that appear to be held by IS-
IS unreachable TRILL Switches; however, it SHOULD give preference
to selecting new nicknames that do not appear to be held by any
TRILL Switch in the campus, reachable or unreachable, so as to
minimize conflicts if IS-IS unreachable TRILL Switches later
become reachable.
4. An RBridge, even after it has acquired a nickname for which there
appears to be no conflicting claimant, MUST continue to monitor
for conflicts with the nickname or nicknames it holds. It does so
by checking in LSP PDUs it receives that should update its link-
state database for the following: any occurrence of any of its
nicknames held with higher priority by some other TRILL Switch
that is IS-IS reachable from it. If it finds such a conflict, it
MUST select a new nickname, even when in overloaded state. (It is
possible to receive an LSP that should update the link-state
database but does not do so due to overload.)
D. Eastlake, et al [Page 19]
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5. In the very unlikely case that an RBridge is unable to obtain a
nickname because all valid RBridge nicknames (0x0001 through
0xFFBF inclusive) are in use with higher priority by IS-IS
reachable TRILL Switches, it will be unable to act as an ingress,
egress, or tree root but will still be able to function as a
transit TRILL Switch. Although it cannot be a tree root, such an
RBridge is included in distribution trees computed for the campus
unless all its neighbors are overloaded. It would not be possible
to send a unicast RBridge Channel message specifically to such a
TRILL Switch [RFC7178]; however, it will receive unicast RBridge
Channel messages sent by a neighbor to the Any-RBridge egress
nickname and will receive appropriate multi-destination RBridge
Channel messages.
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5. MTU (Maximum Transmission Unit) (Unchanged)
MTU values in TRILL key off the originatingL1LSPBufferSize value
communicated in the IS-IS originatingLSPBufferSize TLV [IS-IS]. The
campus-wide value Sz, as described in Section 4.3.1 of [RFC6325], is
the minimum value of originatingL1LSPBufferSize for the RBridges in a
campus, but not less than 1470. The MTU testing mechanism and
limiting LSPs to Sz assures that the LSPs can be flooded by IS-IS and
thus that IS-IS can operate properly.
If an RBridge knows nothing about the MTU of the links or the
originatingL1LSPBufferSize of other RBridges in a campus, the
originatingL1LSPBufferSize for that RBridge should default to the
minimum of the LSP size that its TRILL IS-IS software can handle and
the minimum MTU of the ports that it might use to receive or transmit
LSPs. If an RBridge does have knowledge of link MTUs or other
RBridge originatingL1LSPBufferSize, then, to avoid the necessity to
regenerate the local LSPs using a different maximum size, the
RBridge's originatingL1LSPBufferSize SHOULD be configured to the
minimum of (1) the smallest value that other RBridges are or will be
announcing as their originatingL1LSPBufferSize and (2) a value small
enough that the campus will not partition due to a significant number
of links with limited MTU. However, as provided in [RFC6325], in no
case can originatingL1LSPBufferSize be less than 1470. In a well-
configured campus, to minimize any LSP regeneration due to re-sizing,
all RBridges will be configured with the same
originatingL1LSPBufferSize.
Section 5.1 below corrects errata in [RFC6325], and Section 5.2
clarifies the meaning of various MTU limits for TRILL Ethernet links.
5.1 MTU-Related Errata in RFC 6325
Three MTU-related errata in [RFC6325] are corrected in the
subsections below.
5.1.1 MTU PDU Addressing
Section 4.3.2 of [RFC6325] incorrectly states that multi-destination
MTU-probe and MTU-ack TRILL IS-IS PDUs are sent on Ethernet links
with the All-RBridges multicast address as the Outer.MacDA [Err3004].
As TRILL IS-IS PDUs, when multicast on an Ethernet link, these multi-
destination MTU-probe and MTU-ack PDUs MUST be sent to the All-IS-IS-
RBridges multicast address.
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5.1.2 MTU PDU Processing
As discussed in [RFC6325] and, in more detail, in [RFC7177], MTU-
probe and MTU-ack PDUs MAY be unicast; however, Section 4.6 of
[RFC6325] erroneously does not allow for this possibility [Err3003].
It is corrected by replacing Item numbered "1" in Section 4.6.2 of
[RFC6325] with the following quoted text to which TRILL Switches MUST
conform:
"1. If the Ethertype is L2-IS-IS and the Outer.MacDA is either All-
IS-IS-RBridges or the unicast MAC address of the receiving
RBridge port, the frame is handled as described in Section
4.6.2.1"
The reference to "Section 4.6.2.1" in the above quoted text is to
that section in [RFC6325].
5.1.3 MTU Testing
The last two sentences of Section 4.3.2 of [RFC6325] have errors
[Err3053]. They currently read:
"If X is not greater than Sz, then RB1 sets the "failed minimum
MTU test" flag for RB2 in RB1's Hello. If size X succeeds, and X
> Sz, then RB1 advertises the largest tested X for each adjacency
in the TRILL Hellos RB1 sends on that link, and RB1 MAY advertise
X as an attribute of the link to RB2 in RB1's LSP."
They should read:
"If X is not greater than or equal to Sz, then RB1 sets the
"failed minimum MTU test" flag for RB2 in RB1's Hello. If size X
succeeds, and X >= Sz, then RB1 advertises the largest tested X
for each adjacency in the TRILL Hellos RB1 sends on that link, and
RB1 MAY advertise X as an attribute of the link to RB2 in RB1's
LSP."
5.2 Ethernet MTU Values
originatingL1LSPBufferSize is the maximum permitted size of LSPs
starting with and including the 0x83 Intradomain Routeing Protocol
Discriminator byte. In Layer 3 IS-IS, originatingL1LSPBufferSize
defaults to 1492 bytes. (This is because, in its previous life as
DECnet Phase V, IS-IS was encoded using the SNAP SAP (Sub-Network
Access Protocol Service Access Point) [RFC7042] format, which takes 8
bytes of overhead and 1492 + 8 = 1500, the classic Ethernet maximum.
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When standardized by ISO/IEC [IS-IS] to use Logical Link Control
(LLC) encoding, this default could have been increased by a few bytes
but was not.)
In TRILL, originatingL1LSPBufferSize defaults to 1470 bytes. This
allows 27 bytes of headroom or safety margin to accommodate legacy
devices with the classic Ethernet maximum MTU despite headers such as
an Outer.VLAN.
Assuming the campus-wide minimum link MTU is Sz, RBridges on Ethernet
links MUST limit most TRILL IS-IS PDUs so that PDUz (the length of
the PDU starting just after the L2-IS-IS Ethertype and ending just
before the Ethernet Frame Check Sequence (FCS)) does not to exceed
Sz. The PDU exceptions are TRILL Hello PDUs, which MUST NOT exceed
1470 bytes, and MTU-probe and MTU-ack PDUs that are padded by an
amount that depends on the size being tested (which may exceed Sz).
Sz does not limit TRILL Data packets. They are only limited by the
MTU of the devices and links that they actually pass through;
however, links that can accommodate IS-IS PDUs up to Sz would
accommodate, with a generous safety margin, TRILL Data packet
payloads of (Sz - 24) bytes, starting after the Inner.VLAN and ending
just before the FCS.
Most modern Ethernet equipment has ample headroom for frames with
extensive headers and is sometimes engineered to accommodate 9K byte
jumbo frames.
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6. TRILL Port Modes (Unchanged)
Section 4.9.1 of [RFC6325] specifies four mode bits for RBridge ports
but may not be completely clear on the effects of all combinations of
bits in terms of allowed frame types.
The table below explicitly indicates the effect of all possible
combinations of the TRILL port mode bits. "*" in one of the first
four columns indicates that the bit can be either zero or one. The
following columns indicate allowed frame types. The Disable bit
normally disables all frames, but, as an implementation choice, some
or all low-level Layer 2 control message can still be sent or
received. Examples of Layer 2 control messages are those control
frames for Ethernet identified in Section 1.4 of [RFC6325] or PPP
link negotiation messages [RFC6361].
+-+-+-+-+--------+-------+-------+-------+-------+
|D| | | | | | | | |
|i| |A| | | | TRILL | | |
|s| |c|T| |native | Data | | |
|a| |c|r| |ingress| | | |
|b|P|e|u| | | LSP | | |
|l|2|s|n|Layer 2 |native | SNP | TRILL | P2P |
|e|P|s|k|Control |egress | MTU | Hello | Hello |
+-+-+-+-+--------+-------+-------+-------+-------+
|0|0|0|0| Yes | Yes | Yes | Yes | No |
+-+-+-+-+--------+-------+-------+-------+-------+
|0|0|0|1| Yes | No | Yes | Yes | No |
+-+-+-+-+--------+-------+-------+-------+-------+
|0|0|1|0| Yes | Yes | No | Yes | No |
+-+-+-+-+--------+-------+-------+-------+-------+
|0|0|1|1| Yes | No | No | Yes | No |
+-+-+-+-+--------+-------+-------+-------+-------+
|0|1|0|*| Yes | No | Yes | No | Yes |
+-+-+-+-+--------+-------+-------+-------+-------+
|0|1|1|*| Yes | No | No | No | Yes |
+-+-+-+-+--------+-------+-------+-------+-------+
|1|*|*|*|Optional| No | No | No | No |
+-+-+-+-+--------+-------+-------+-------+-------+
The formal name of the "access bit" above is the "TRILL traffic
disable bit". The formal name of the "trunk bit" is the "end-station
service disable bit" [RFC6325].
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7. The CFI/DEI Bit (Unchanged)
In May 2011, the IEEE promulgated IEEE Std 802.1Q-2011, which changed
the meaning of the bit between the priority and VLAN ID bits in the
payload of C-VLAN tags. Previously, this bit was called the CFI
(Canonical Format Indicator) bit [802] and had a special meaning in
connection with IEEE 802.5 (Token Ring) frames. Now, after
802.1Q-2011 and in subsequent versions the current of which is
[802.1Q-2014], it is a DEI (Drop Eligibility Indicator) bit, similar
to that bit in S-VLAN/B-VLAN tags where this bit has always been a
DEI bit.
The TRILL base protocol specification [RFC6325] assumed, in effect,
that the link by which end stations are connected to TRILL Switches
and the restricted virtual link provided by the TRILL Data packet are
IEEE 802.3 Ethernet links on which the CFI bit is always zero.
Should an end station be attached by some other type of link, such as
a Token Ring link, [RFC6325] implicitly assumed that such frames
would be canonicalized to 802.3 frames before being ingressed, and
similarly, on egress, such frames would be converted from 802.3 to
the appropriate frame type for the link. Thus, [RFC6325] required
that the CFI bit in the Inner.VLAN, which is shown as the "C" bit in
Section 4.1.1 of [RFC6325], always be zero.
However, for TRILL Switches with ports conforming to the change
incorporated in the IEEE 802.1Q-2011 standard, the bit in the
Inner.VLAN, now a DEI bit, MUST be set to the DEI value provided by
the port interface on ingressing a native frame. Similarly, this bit
MUST be provided to the port when transiting or egressing a TRILL
Data packet. As with the 3-bit Priority field, the DEI bit to use in
forwarding a transit packet MUST be taken from the Inner.VLAN. The
exact effect on the Outer.VLAN DEI and priority bits and whether or
not an Outer.VLAN appears at all on the wire for output frames may
depend on output port configuration.
TRILL campuses with a mixture of ports, some compliant with versions
of 802.1Q from IEEE Std 802.1Q-2011 onward and some compliant with
pre-802.1Q-2011 standards, especially if they have actual Token Ring
links, may operate incorrectly and may corrupt data, just as a
bridged LAN with such mixed ports and links would.
D. Eastlake, et al [Page 25]
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8. Other IS-IS Considerations (Changed)
This section covers E-L1FS Support, Control Packet Priorities,
Unknown PDUs, the Nickname Flags APPsub-TLV, Graceful Restart, and
Purge Originator Identification.
8.1 E-L1FS Support (New)
TRILL switches MUST support Extended Level 1 Flooding Scope PDUs (E-
L1FS) [RFC7356] and MUST include a Scoped Flooding Support TLV
[RFC7356] in all TRILL Hellos they send indicating support for this
scope and any other FS-LSP scopes that they support. This support
increases the number of fragments available for link state
information by over two orders of magnitude. (See Section 9 for
further information on support of the Scoped Flooding Support TLV.)
In addition, TRILL switches MUST advertise their support of E-L1FS
flooding in a TRILL Version sub-TLV capability bit (see [RFC7176] and
Section 12.2). This bit is used by a TRILL switch, say RB1, to
determine support for E-L1FS by some remote RBx. The alternative of
simply looking for an E-L1FS FS-LSP originated by RBx fails because
(1) RBx might support E-L1FS flooding but not be originating any E-
L1FS FS-LSPs and (2) even if RBx is originating E-L1FS FS-LSPs there
might, due to legacy TRILL switches in the campus, be no path between
RBx and RB1 through TRILL switches supporting E-L1FS flooding. If
that were the case, no E-L1FS FS-LSP originated by RBx could get to
RB1.
E-L1FS will commonly be used to flood TRILL GENINFO TLVs and enclosed
TRILL APPsub-TLVs [RFC7357]. For robustness, E-L1FS fragment zero
MUST NOT exceed 1470 bytes in length; however, if such a fragment is
received that is larger, it is processed normally. It is anticipated
that in the future, some particularly important TRILL APPsub-TLVs
will be specified as being flooded in E-L1FS fragment zero. TRILL
GENINFO TLVs MUST NOT be sent in LSPs; however, if one is received in
an LSP, it is processed normally.
8.1.1 Backward Compatibility
A TRILL campus might contain TRILL switches supporting E-L1FS
flooding and legacy TRILL switches that do not support E-L1FS or
perhaps do not support any [RFC7356] scopes.
A TRILL switch conformant to this document can always tell which
adjacent TRILL switches support E-L1FS flooding from the adjacency
table entries on its ports (see Section 9). In addition, such a TRILL
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switch can tell which remote TRILL switches in a campus support E-
L1FS by the presence of a TRILL Version sub-TLV in that TRILL
switch's LSP with the E-L1FS support bit set in the Capabilities
field; this capability bit is ignored for adjacent TRILL switches for
which only the adjacency table entry is consulted to determine E-L1FS
support.
TRILL specifications making use of E-L1FS MUST specify how situations
involving mixed TRILL campus of TRILL switches will be handled.
8.1.2 E-L1FS Use for Existing (sub)TLVs
In a campus where all TRILL switches support E-L1FS, all TRILL sub-
TLVs listed in Section 2.3 of [RFC7176], except the TRILL Version
sub-TLV, MAY be advertised by inclusion in Router Capability or MT-
Capability TLVs in E-L1FS FS-LSPs [RFC7356]. (The TRILL Version sub-
TLV still MUST appear in an LSP fragment zero.)
In a mixed campus where some TRILL switches support E-L1FS and some
do not, then only the following four sub-TLVs of those listed in
Section 2.3 of [RFC7176] can appear in E-L1FS and then only under the
conditions discussed below. In the following list, each sub-TLV is
preceded by an abbreviated acronym used only in this Section 8.1.2:
IV: Interested VLANs and Spanning Tree Roots sub-TLV
VG: VLAN Groups sub-TLV
IL: Interested Labels and Spanning Tree Roots sub-TLV
LG: Label Groups sub-TLV
An IV or VG sub-TLV MUST NOT be advertised by TRILL switch RB1 in an
E-L1FS FS-LSP (instead being advertised in an LSP) unless the
following conditions are met:
- E-L1FS is supported by all of the TRILL switches that are data
reachable from RB1 and are interested in the VLANs mentioned in
the IV or VG sub-TLV, and
- there is E-L1FS connectivity between all such TRILL switches in
the campus interested in the VLANs mentioned in the IV or VG sub-
TLV (connectivity involving only intermediate TRILL switches that
also support E-L1FS).
Any IV and VG sub-TLVs MAY still be advertised via core TRILL IS-IS
LSP by any TRILL switch that has enough room in its LSPs.
The conditions for using E-L1FS for the IL and LG sub-TLVs are the
same as for IV and VG but with Fine Grained Labels [RFC7172]
substituted for VLANs.
Note, for example, that the above would permit a contiguous subset
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of the campus that supported Fine Grained Labels and E-L1FS to use
E-L1FS to advertise IL and LG sub-TLVs even if the remainder of
the campus did not support Fine Grained Labels or E-L1FS.
8.2 Control Packet Priorities (New)
When deciding what packet to send out a port, control packets used to
establish and maintain adjacency between TRILL switches SHOULD be
treated as being in the highest priority category. This includes
TRILL IS-IS Hello and MTU PDUs and possibly other adjacency [RFC7177]
or link technology specific packets. Other control and data packets
SHOULD be given lower priority so that a flood of such other packets
cannot lead to loss of or inability to establish adjacency. Loss of
adjacency causes a topology transient that can result in reduced
throughput, re-ordering, increased probability of loss of data, and,
in the worst case, if the adjacency is a cut point, network
partition.
Other important control packets should be given second highest
priority. Lower priorities should be given to data or less important
control packets.
Based on the above, control packets can be ordered into priority
categories as shown below based on the relative criticality of these
types of messages, where the most critical relate to the core routing
between TRILL switches and the less critical are closer to
"application" information. (There may be additional control packets,
not specifically listed in any category below, that SHOULD be handled
as being in the most nearly analogous category.) Although few
implementations will actually treat these four categories with
different priority, an implementation MAY choose to prioritize more
critical messages over less critical. However, an implementation
SHOULD NOT send control packets in a lower priority category with a
priority above those in a higher priority category as, under
sufficiently congested conditions, this could block control packets
in a higher priority category, resulting in network disruption.
Priority
Category Description
-------- --------------
4. Hello, MTU-probe, MTU-ack, and other packets critical to
establishing and maintaining adjacency. (Normally sent
with highest priority 7.)
3. LSPs, CSNP/PSNPs, and other important control packets,
2. Circuit scoped FS-LSP, FS-CSNP, and FS-PSNPs.
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1. Non-circuit scoped FS-LSP, FS-CSNP, and FS-PSNPs.
8.3 Unknown PDUs (New)
TRILL switches MUST silently discard [IS-IS] PDUs they receive with
PDU numbers they do not understand, just as they ignore TLVs and sub-
TLVs they receive that have unknown Types and sub-Types; however,
they SHOULD maintain a counter of how many such PDUs have been
received, on a per PDU number basis. (This is not burdensome as the
PDU number is only a 5-bit field.)
Note: The set of valid [IS-IS] PDUs was stable for so long that
some IS-IS implementations may treat PDUs with unknown PDU
numbers as a serious error and, for example, an indication that
other valid PDUs from the sender are not to be trusted or that
they should drop adjacency to the sender if it was adjacent.
However, the MTU-probe and MTU-ack PDUs were added by [RFC7176]
and now [RFC7356] has added three more new PDUs. While the
authors of this document are not aware of any Internet drafts
calling for further PDUs, the eventual addition of further new
PDUs should not be surprising.
8.4 Nickname Flags APPsub-TLV (New)
An optional Nickname Flags APPsub-TLV within the TRILL GENINFO TLV
[RFC7357] is specified below.
1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = NickFlags (#tbd2) | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length = 4*K | (2 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NICKFLAG RECORD 1 (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| NICKFLAG RECORD K (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Where each NICKFLAG RECORD has the following format:
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0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| Nickname |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|IN| RESV |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
o Type: NickFlags TRILL APPsub-TLV, set to tbd2 (NICKFLAGS)
o Length: 4 times the number of NICKFLAG RECORDS present.
o Nickname: A 16-bit TRILL nickname held by the advertising TRILL
switch ([RFC6325] and Section 4).
o IN: Ingress. If this flag is one, it indicates the advertising
TRILL switch may use the nickname in the NICKFLAG RECORD as the
ingress nickname of TRILL Headers it creates. If the flag is
zero, that nickname will not be used for that purpose.
o RESV: Reserved for additional flags to be specified in the
future. MUST be sent as zero and ignored on receipt.
The entire NickFlags APPsub-TLV is ignored if the Length is not a
multiple of 4. A NICKFLAG RECORD is ignored if the nickname it lists
is not a nickname owned by the TRILL switch advertising the enclosing
NickFlags APPsub-TLV.
If a TRILL switch intends to use a nickname in the ingress nickname
field of TRILL Headers it constructs, it can advertise this through
E-L1FS FS-LSPs (see Section 8.1) using a NickFlags APPsub-TLV entry
with the IN flag set. If it owns only one nickname, there is no
reason to do this because, if a TRILL switch advertises no NickFlags
APPsub-TLVs with the IN flag set for nicknames it owns, it is assumed
that the TRILL switch might use any or all nicknames it owns as the
ingress nickname in TRILL Headers it constructs. If a TRILL switch
advertises any NickFlags APPsub-TLV entries with the IN flag set,
then it MUST NOT use any other nickname(s) it owns as the ingress
nickname in TRILL Headers it constructs.
Every reasonable effort should be made to be sure that Nickname sub-
TLVs [RFC7176] and NickFlags APPsub-TLVs remain in sync. If all TRILL
switches in a campus support E-L1FS, so that Nickname sub-TLVs can be
advertised in E-L1FS FS-LSPs, then the Nickname sub-TLV and any
NickFlags APPsub-TLVs for any particular nickname SHOULD be
advertised in the same fragment. If they are not in the same fragment
then, to the extent practical, all fragments involving those sub-TLVs
for the same nickname should be propagated as an atomic action. If a
TRILL switch sees multiple NickFlags APPsub-TLV entries for the same
nickname, it assumes that nickname might be used as the ingress in a
TRILL Header if any of the NickFlags APPsub-TLV entries have the IN
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bit set.
It is possible that a NickFlags APPsub-TLV would not be propagated
throughout the TRILL campus due to legacy TRILL switches not
supporting E-L1FS. In that case, Nickname sub-TLVs MUST be advertised
in LSPs and TRILL switches not receiving NickFlags APPsub-TLVs having
entries with the IN flag set will simply assume that the source TRILL
switch might use any of its nicknames as ingress in constructing
TRILL Headers. Thus the use of this optional APPsub-TLV is backwards
compatible with legacy lack of E-L1FS support.
(Additional flags are assigned from those labeled RESV above and
specified in [irb] and [centralized-replication], works in progress.)
8.5 Graceful Restart (Unchanged)
TRILL Switches SHOULD support the features specified in [RFC5306],
which describes a mechanism for a restarting IS-IS router to signal
to its neighbors that it is restarting, allowing them to reestablish
their adjacencies without cycling through the down state, while still
correctly initiating link-state database synchronization. If this
feature is not supported, it may increase the number of topology
transients cause by a TRILL switch rebooting due to errors or
maintenance.
8.6 Purge Originator Identification (New)
To ease debugging of any purge related problems, TRILL switches
SHOULD include the Purge Originator Identification TLV [RFC6232] in
all purge PDUs in TRILL IS-IS including Flooding Scoped purges
[RFC7356] and in ESADI [RFC7357].
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9. Updates to [RFC7177] (Adjacency) (Changed)
To support the E-L1FS flooding scope [RFC7356] mandated by Section
8.1 and backwards compatibility with legacy RBridges not supporting
E-L1FS flooding, the following changes are made to [RFC7177]:
1. The list in the second paragraph of [RFC7177] Section 3.1 has the
following item added:
- The Scoped Flooding Support TLV.
In addition, the sentence immediately after that list is modified to
read as follows:
Of course, the priority, Desired Designated VLAN, Scoped Flooding
Support TLV, and possibly the inclusion or value of the PORT-
TRILL-VER sub-TLV, and/or BFD-Enabled TLV could change on
occasion, but then the new value(s) must similarly be used in all
TRILL Hellos on the LAN port, regardless of VLAN.
2. An additional bullet item is added to the end of Section 3.2 of
[RFC7177] as follows:
o The value from the Scoped Flooding Support TLV or a null string
if none was included.
3. Near the bottom of Section 3.3 of [RFC7177] a bullet item as
follows is added:
o The variable length value part of the Scoped Flooding Support
TLV in the Hello or a null string if that TLV does not occur in
the Hello.
4. At the beginning of Section 4 of [RFC7177], a bullet item is added
to the list as follows:
o The variable length value part of the Scoped Flooding Support
TLV used in TRILL Hellos sent on the port.
5. Add a line to Table 4: TRILL Hello Contents in Section 9.1 of
[RFC7177] as follows:
LAN P2P Number Content Item
--- --- ------ -----------------------------
M M 1 Scoped Flooding Support TLV
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10. TRILL Header Update (New)
The TRILL header has been updated from its original specification in
[RFC6325] by [RFC7455] and [RFC7179] and is further updated by this
document. The TRILL header is now as shown in the figure below which
is followed by references for all of the fields. Those fields for
which the reference is only to [RFC6325] are unchanged from that RFC.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| V |A|C|M| RESV |F| Hop Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Egress Nickname | Ingress Nickname |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Optional Flag Word :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In calculating a TRILL Data packet hash as part of equal-cost multi-
path selection, a TRILL switch MUST ignore the value of the "A" and
"C" bits.
In [RFC6325] and [RFC7179] there is an "Ex-Length" or TRILL Header
Extensions Length field which is hereby changed to consist of the
RESV and F fields above.
o V (Version): 2-bit unsigned integer. See Section 3.2 of [RFC6325].
o A (Alert): 1 bit. See [RFC7455].
o C (Color): 1 bit. See Section 10.1.
o M (Multi-destination): 1 bit. See Section 3.4 of [RFC6325].
o RESV: 4 bits. These bits are reserved and MUST be sent as zero.
Due to the previous use of these bits specified in [RFC6325], most
TRILL fast path hardware implementations trap and do not forward
TRILL Data packets with these bits non-zero. A TRILL switch
receiving a TRILL Data packet with any of these bits non-zero MUST
discard the packet unless the non-zero bit or bits have some
future use specified that the TRILL switch understands.
o F: 1 bit. If this field is non-zero, then the optional Flag Word
described in Section 10.2 is present. If it is zero, the Flag Word
is not present.
o Hop Count: 6 bits. See Section 3.6 of [RFC6325] and Section 10.2.1
below.
o Egress Nickname. See Section 3.7.1 of [RFC6325].
o Ingress Nickname. See Section 3.7.2 of [RFC6325].
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o Optional Flag Word: See [RFC7179] and Section 10.2.
10.1 Color Bit
The Color bit provides an optional way ingress TRILL switches MAY
mark TRILL Data packets for implementation specific purposes.
Transit TRILL switches MUST NOT change this bit. Transit and egress
TRILL switches MAY use the Color bit for implementation dependent
traffic labeling or statistical or other traffic study or analysis.
10.2 Flag Word Changes (update to [RFC7179])
When the F bit in the TRILL Header is non-zero, the first 32 bits
after the Ingress nickname field provides additional flags. These
bits are as specified in [RFC7179] except as changed by the
subsections below that provide extended Hop Count and extended Color
fields. See Section 10.3 for a diagram and summary of these fields.
10.2.1 Extended Hop Count
The TRILL base protocol [RFC6325] specifies the Hop Count field in
the header, to avoid packets persisting in the network due to looping
or the like. However, the Hop Count field size (6 bits) limits the
maximum hops a TRILL Data packet can traverse to 64. Optionally,
TRILL switches can use a field composed of bits 14 through 16 in the
Flag Word, as specified below, to extend this field to 9 bits. This
increases the maximum Hop Count to 512. Except in rare circumstances,
reliable use of Hop Counts in excess of 64 requires support of this
optional capability at all TRILL switches along the path of a TRILL
Data packet.
10.2.1.1 Advertising Support
In case of a TRILL campus such that the unicast calculated path, plus
a reasonable allowance for alternate pathing, or the distribution
tree calculated path, traverse more than 64 hops, it may be that not
all the TRILL switches support the extended Hop Count mechanism. As
such it is required that TRILL switches advertise their support by
setting bit 14 in the TRILL Version Sub-TLV Capabilities and Header
Flags Supported field [RFC7176]; bits 15 and 16 of that field are now
specified as Unassigned (see Section 12.2.5).
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10.2.1.2 Ingress Behavior
If an ingress TRILL switch determines it should set the hop count for
a TRILL Data packet to 63 or less, then behavior is as specified in
the TRILL base protocol [RFC6325]. If the optional TRILL Header Flag
Word is present, bits 14, 15, and 16 and the Critical Reserved bit of
the Critical Summary Bits are zero.
If the hop count for a TRILL Data packet should be set to some value
greater than 63 but less than 512 and all TRILL switches that the
packet is reasonably likely to encounter support extended Hop Count,
then the resulting TRILL Header has the Flag Word extension present,
the high order three bits of the desired hop count are stored in the
extended Hop Count field in the Flag Word, the five low order bits
are stored in the Hop Count field in the first word of the TRILL
Header, and bit two (the Critical Reserved bit of the Critical
Summary Bits) in the Flag Word is set to one.
For known unicast traffic (TRILL Header M bit zero), an ingress TRILL
switch discards the frame if it determines that the least cost path
to the egress is (1) more than 64 hops and not all TRILL switches on
that path support the extended Hop Count feature or (2) more than 512
hops.
For multi-destination traffic, when a TRILL switch determines that
one or more tree paths from the ingress are more than 64 hops and not
all TRILL switches in the campus support the extended Hop Count
feature, the encapsulation uses a total Hop Count of 63 to obtain at
least partial distribution of the traffic.
10.2.1.3 Transit Behavior
A transit TRILL switch supporting extended Hop Count behaves like a
base protocol [RFC6325] TRILL switch in decrementing the hop count
except that it considers the hop count to be a 9 bit field where the
extended Hop Count field constitutes the high order three bits.
To be more precise: a TRILL switch supporting extended Hop Count
takes the first of the following actions that is applicable:
1. If both the Hop Count and extended Hop Count fields are zero, the
packet is discarded.
2. If the Hop Count is non-zero, it is decremented. As long as the
extended Hop Count is non-zero, no special action is taken. If the
result of this decrement is zero, the packet is processed
normally.
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3. If the Hop Count is zero, it is set to the maximum value of 63 and
the extended Hop Count is decremented. If this results in the
extended Hop Count being zero, the Critical Reserved bit in the
Critical Summary bits is set to zero.
10.2.1.4 Egress Behavior
No special behavior is required when egressing a TRILL Data packet
that uses the extended Hop Count. The Flag Word, if present, is
removed along with the rest of the TRILL Header during decapsulation.
10.2.2 Extended Color Field
Flag Word bits 27 and 28 are specified to be a two-bit Extended Color
field (see Section 10.3). These bits are in the non-critical ingress-
to-egress region of the Flag Word.
The Extended Color field provides an optional way by which ingress
TRILL switches MAY mark TRILL Data packets for implementation
specific purposes. Transit TRILL switches MUST NOT change these bits.
Transit and egress TRILL switches MAY use the Extended Color bits for
implementation dependent traffic labeling or statistical or other
traffic study or analysis.
As provided in Section 2.3.1 of [RFC7176], support for these bits is
indicated by the same bits (27 and 28) in the Capabilities and Header
Flags Supported field of the TRILL Version Sub-TLV. If these bits are
zero in those capabilites, Extended Color is not supported. A TRILL
switch that does not support Extended Color will ignore the
corresponding bits in any TRILL Header Flag Word it receives as part
of a TRILL Data Packet and will set those bits to zero in any TRILL
Header Flag word it creates. A TRILL switch that sets or senses the
Extended Color field on transmitting or receiving TRILL Data packets
MUST set the corresponding 2-bit field in the TRILL Version Sub-TLV
non-zero. Any difference in meaning of the three possible non-zero
values of this 2-bit capability field (0b01, 0b10 or 0b11) is
implementation dependent.
10.3 Updated Flag Word Summary
With the changes above, the 32-bit Flag Word extension to the TRILL
Header [RFC7179], appearing as the "TRILL Extended Header Flags"
registry on the TRILL Parameters IANA web page, is now as follows:
D. Eastlake, et al [Page 36]
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Crit.| CHbH | NCHbH |CRSV | NCRSV | CItE | NCItE |
|.....|.........|...........|.....|.......|...........|.........|
|C|C|C| |C|N| | Ext | | |Ext| |
|R|R|R| |R|C| | Hop | | |Clr| |
|H|I|R| |C|C| | Cnt | | | | |
|b|t|s| |A|A| | | | | | |
|H|E|v| |F|F| | | | | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Bit 0 to 2 are the Critical Summary bits as specified in [RFC7179]
consisting of the Critical Hop-by-Hop, Critical Ingres-to-Egress, and
Critical Reserved bits, respectively. The next two fields are
specific Critical and Non-Critical Hop-by-Hop bits, CHbH and NCHbH,
respectively, containing the Critical and Non-Critical Channel Alert
flags as specified in [RFC7179]. The next field is the Critical
Reserved bits (CRSV) that are specified herein to be the Extended Hop
Count. Then the Non-Critical Reserved Bits (NCRSV) and the Critical
Ingress-to-Egress bits (CITE) as specified in [RFC7179]. Finally,
there is the Non-Critical Ingress-to-Egress field including bits 27
and 28 that are specified herein as the Extended Color field.
D. Eastlake, et al [Page 37]
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11. Appointed Forwarder Status Lost Counter (New)
Strict conformance to the provisions of Section 4.8.3 of [RFC6325] on
the value of the Appointed Forwarder Status Lost Counter can result
in splitting of Interested VLANs and Spanning Tree Roots sub-TLVs
[RFC7176] (or the corresponding Interested Labels sub-TLVs where a
VLAN is mapped to an FGL) due to differences in this counter value
for adjacent VLAN IDs (or 24-bit FGLs). This counter is a mechanism
to optimize data plane learning by trimming the expiration timer for
learned addresses on a per VLAN/FGL basis under some circumstances.
The requirement to increment this counter by one whenever a TRILL
switch loses appointed forwarder status on a port is hereby changed
from the mandatory provisions of [RFC6325] to the enumerated
provisions below. To the extent that this might cause the Appointed
Forwarder Status Lost Counter to be increased when [RFC6325]
indicates it should not, this will cause data plane address learning
timeouts at remote TRILL switches to be reduced. To the extent that
this might cause the Appointed Forwarder Status Lost Counter to
remain unchanged when [RFC6325] indicate it should be increased, this
will defeat a reduction in such timeouts that would otherwise occur.
(1) If any of the following apply, either data plane address learning
is not in use or Appointed Forwarder status is irrelevant. In
these cases the Appointed Forwarder Status Lost Counter MAY be
left zero or set to any convenient value such as the value of the
Appointed Forwarder Status Lost Counter for an adjacent VLAN ID
or FGL.
(1a) The TRILL switch port has been configured with the "disable
end station traffic" bit on (also known as the trunk bit).
(1b) The TRILL switch port has been configured in IS-IS as an IS-
IS point-to-point link.
(1C) If the TRILL switch is relying on ESADI [RFC7357] or
Directory Assist [RFC7379] and not using data plane learning.
(2) In cases other than those numerated in point 1 above, the
Appointed Forwarder Status Lost Counter SHOULD be incremented as
described in [RFC6325]. Such incrementing has the advantage of
optimizing data plane learning. Alternatively, the value of the
Appointed Forwarder Status Lost Counters can deviate from that
value, for example to make it match the value for an adjacent
VLAN ID (or FGL), so as to permit greater aggregation of
Interested VLANs and Spanning Tree Roots sub-TLVs.
D. Eastlake, et al [Page 38]
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12. IANA Considerations (Changed)
This section gives IANA actions previously completed and new IANA
actions.
12.1 Previously Completed IANA Actions (Unchanged)
The following IANA actions were completed as part of [RFC7180] and
are included here for completeness, since this document obsoletes
[RFC7180].
1. The nickname 0xFFC1, which was reserved by [RFC6325], is allocated
for use in the TRILL Header Egress Nickname field to indicate an
OOMF (Overload Originated Multi-destination Frame).
2. Bit 1 from the seven previously reserved (RESV) bits in the per-
neighbor "Neighbor RECORD" in the TRILL Neighbor TLV [RFC7176] is
allocated to indicate that the RBridge sending the TRILL Hello
volunteers to provide the OOMF forwarding service described in
Section 2.4.2 to such frames originated by the TRILL Switch whose
SNPA (MAC address) appears in that Neighbor RECORD. The
description of this bit is "Offering OOMF service".
3. Bit 0 is allocated from the Capability bits in the PORT-TRILL-VER
sub-TLV [RFC7176] to indicate support of the VLANs Appointed sub-
TLV [RFC7176] and the VLAN inhibition setting mechanisms specified
in [rfc6439bis]. The description of this bit is "Hello reduction
support".
12.2 New IANA Actions (New)
The following are new IANA actions for this document:
12.2.1 Reference Updated
All references to [RFC7180] in the TRILL Parameters Registry are
replaced with references to this document except that the Reference
for bit 0 in the PORT-TRILL-VER Sub-TLV Capability Flags is changed
to [rfc6439bis].
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12.2.2 The 'E' Capability Bit
There is an existing TRILL Version sub-TLV, sub-TLV #13 under both
TLV #242 and TLV #144 [RFC7176]. This TRILL Version sub-TLV contains
a capability bits field for which assignments are documented in the
"TRILL-VER Sub-TLV Capability Flags" registry on the TRILL Parameters
IANA web page. IANA has allocated tbd1 from the previous reserved
bits in this TRILL-VER Sub-TLV Capability Flags registry to indicate
support of the E-L1FS flooding scope as specified in Section 8.1.
This capability bit is referred to as the "E" bit. The following is
the addition to the TRILL-VER Sub-TLV Capability Flags registry:
Bit Description References
---- --------------------- ---------------
tbd1 E-L1FS FS-LSP support [this document][RFC7356]
12.2.3 NickFlags APPsub-TLV Number and Registry
IANA has assigned tbd2 APPsub-TLV number under the TRILL GENINFO TLV
from the range less than 255.
Type Name References
---- --------- -----------
tbd2 NICKFLAGS [this document]
In addition, IANA has created a registry on the TRILL Parameters web
page for NickFlags bit assignments as follows:
Name: NickFlags Bits
Registration Procedure: IETF Review
Reference: [this document]
Bit Mnemonic Description Reference
----- -------- ----------- ---------
0 IN Used as ingress [this document]
1-15 - Unassigned [this document]
12.2.4 Updated TRILL Extended Header Flags
Update the "TRILL Extended Header Flags" registry as follows:
D. Eastlake, et al [Page 40]
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Bits Purpose References
----- ------------------------------------------ ------------
14-16 Extended Hop Count [this document]
27-28 Extended Color [this document]
29-31 Available non-critical ingress-to-egress flags
[RFC7179] [this document]
12.2.5 TRILL-VER Sub-TLV Capability Flags
Update the "TRILL-VER Sub-TLV Capability Flags" registry as follows:
Bit Description Reference
----- -------------------------- ----------------
14 Extended Hop Count support [this document]
15-16 Unassigned [this document]
27-28 Extended Color support [this document]
29-31 Extended header flag support [RFC7179] [this document]
12.2.6 Example Nicknames
IANA has assigned a block of four nicknames for use as examples in
documentation such as in Appendix B below. The TRILL Nicknames
registry has been updated by changing the previous "0xFFC2-0xFFFE
Unassigned" line to the following:
Name Description Reference
------------- -------------- -----------
0xFFC2-0xFFD7 Unassigned
0xFFD8-0xFFDF For use in documentation examples [this document]
0xFFE0-0xFFFE Unassigned
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13. Security Considerations (Changed)
See [RFC6325] for general TRILL security considerations.
This memo improves the documentation of the TRILL protocol, corrects
five errata in [RFC6325], updates [RFC6325], [RFC7177], and [RFC7179]
and obsoletes [RFC7180]. It does not change the security
considerations of those RFCs except as follows:
E-L1FS FS-LSPs can be authenticated with IS-IS security [RFC5310],
that is, through the inclusion of an IS-IS Authentication TLV in
E-L1FS PDUs.
As discussed in Section 3.6, when using an allowed weaker RPF check
under very rare topolgoies and transient conditions, multi-
destination TRILL Data packets can be duplicated, which could have
secuirty consequences for some protocols.
D. Eastlake, et al [Page 42]
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Normative References
[802.1Q-2014] - IEEE, "IEEE Standard for Local and metropolitan area
networks -- Media Access Control (MAC) Bridges and Virtual
Bridged Local Area Networks", IEEE Std 802.1Q-2014, 19 December
2014.
[IS-IS] - International Organization for Standardization,
"Intermediate System to Intermediate System intra-domain
routeing information exchange protocol for use in conjunction
with the protocol for providing the connectionless-mode network
service (ISO 8473)", Second Edition, November 2002.
[RFC2119] - Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5305] - Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.
[RFC5306] - Shand, M. and L. Ginsberg, "Restart Signaling for IS-IS",
RFC 5306, October 2008.
[RFC5310] - Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic Authentication", RFC
5310, February 2009, <http://www.rfc-editor.org/info/rfc5310>.
[RFC6232] - Wei, F., Qin, Y., Li, Z., Li, T., and J. Dong, "Purge
Originator Identification TLV for IS-IS", RFC 6232, May 2011,
<http://www.rfc-editor.org/info/rfc6232>.
[RFC6325] - Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
Ghanwani, "Routing Bridges (RBridges): Base Protocol
Specification", RFC 6325, July 2011.
[RFC6361] - Carlson, J. and D. Eastlake 3rd, "PPP Transparent
Interconnection of Lots of Links (TRILL) Protocol Control
Protocol", RFC 6361, August 2011.
[RFC7172] - Eastlake 3rd, D., Zhang, M., Agarwal, P., Perlman, R.,
and D. Dutt, "Transparent Interconnection of Lots of Links
(TRILL): Fine-Grained Labeling", RFC 7172, May 2014.
[RFC7176] - Eastlake 3rd, D., Senevirathne, T., Ghanwani, A., Dutt,
D., and A. Banerjee, "Transparent Interconnection of Lots of
Links (TRILL) Use of IS-IS", RFC 7176, May 2014.
[RFC7177] - Eastlake 3rd, D., Perlman, R., Ghanwani, A., Yang, H.,
and V. Manral, "Transparent Interconnection of Lots of Links
(TRILL): Adjacency", RFC 7177, May 2014.
D. Eastlake, et al [Page 43]
INTERNET-DRAFT TRILL: Clarifications, Corrections, and Updates
[RFC7179] - Eastlake 3rd, D., Ghanwani, A., Manral, V., Li, Y., and
C. Bestler, "Transparent Interconnection of Lots of Links
(TRILL): Header Extension", RFC 7179, May 2014,
<http://www.rfc-editor.org/info/rfc7179>.
[RFC7356] - Ginsberg, L., Previdi, S., and Y. Yang, "IS-IS Flooding
Scope Link State PDUs (LSPs)", RFC 7356, September 2014,
<http://www.rfc-editor.org/info/rfc7356>.
[RFC7455] - Senevirathne, T., Finn, N., Salam, S., Kumar, D.,
Eastlake 3rd, D., Aldrin, S., and Y. Li, "Transparent
Interconnection of Lots of Links (TRILL): Fault Management",
RFC 7455, March 2015, <http://www.rfc-editor.org/info/rfc7455>.
Informative References
[802] - IEEE 802, "IEEE Standard for Local and metropolitan area
networks: Overview and Architecture", IEEE Std 802.1-2014, 12
June 2014.
[centralized-replication] - Weiguo Hao, et al., "Centralized
Replication for BUM traffic in active-active edge connection",
draft-ietf-trill-centralized-replication, Work in Progress.
[irb] - Weiguo Hao, et al., "TRILL Distributed Layer 3 Gateway",
draft-ietf-trill-irb, Work in Progress.
[Err3002] - RFC Errata, Errata ID 3002, RFC 6325, <http://www.rfc-
editor.org>.
[Err3003] - RFC Errata, Errata ID 3003, RFC 6325, <http://www.rfc-
editor.org>.
[Err3004] - RFC Errata, Errata ID 3004, RFC 6325, <http://www.rfc-
editor.org>.
[Err3052] - RFC Errata, Errata ID 3052, RFC 6325, <http://www.rfc-
editor.org>.
[Err3053] - RFC Errata, Errata ID 3053, RFC 6325, <http://www.rfc-
editor.org>.
[Err3508] - RFC Errata, Errata ID 3508, RFC 6325, <http://rfc-
editor.org>.
[RFC826] - Plummer, D., "Ethernet Address Resolution Protocol: Or
Converting Network Protocol Addresses to 48.bit Ethernet
Address for Transmission on Ethernet Hardware", STD 37, RFC
D. Eastlake, et al [Page 44]
INTERNET-DRAFT TRILL: Clarifications, Corrections, and Updates
826, November 1982, <http://www.rfc-editor.org/info/rfc826>.
[RFC792] - Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, September 1981, <http://www.rfc-
editor.org/info/rfc792>.
[RFC4086] - Eastlake 3rd, D., Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086, June
2005, <http://www.rfc-editor.org/info/rfc4086>.
[RFC6327] - Eastlake 3rd, D., Perlman, R., Ghanwani, A., Dutt, D.,
and V. Manral, "Routing Bridges (RBridges): Adjacency", RFC
6327, July 2011, <http://www.rfc-editor.org/info/rfc6327>.
[RFC6439] - Perlman, R., Eastlake, D., Li, Y., Banerjee, A., and F.
Hu, "Routing Bridges (RBridges): Appointed Forwarders", RFC
6439, November 2011, <http://www.rfc-editor.org/info/rfc6439>.
[RFC7042] - Eastlake 3rd, D. and J. Abley, "IANA Considerations and
IETF Protocol and Documentation Usage for IEEE 802 Parameters",
BCP 141, RFC 7042, October 2013.
[RFC7175] - Manral, V., Eastlake 3rd, D., Ward, D., and A. Banerjee,
"Transparent Interconnection of Lots of Links (TRILL):
Bidirectional Forwarding Detection (BFD) Support", RFC 7175,
May 2014.
[RFC7178] - Eastlake 3rd, D., Manral, V., Li, Y., Aldrin, S., and D.
Ward, "Transparent Interconnection of Lots of Links (TRILL):
RBridge Channel Support", RFC 7178, May 2014.
[RFC7180] - Eastlake 3rd, D., Zhang, M., Ghanwani, A., Manral, V.,
and A. Banerjee, "Transparent Interconnection of Lots of Links
(TRILL): Clarifications, Corrections, and Updates", RFC 7180,
May 2014.
[RFC7357] - Zhai, H., Hu, F., Perlman, R., Eastlake 3rd, D., and O.
Stokes, "Transparent Interconnection of Lots of Links (TRILL):
End Station Address Distribution Information (ESADI) Protocol",
RFC 7357, September 2014, <http://www.rfc-
editor.org/info/rfc7357>.
[RFC7379] - Li, Y., Hao, W., Perlman, R., Hudson, J., and H. Zhai,
"Problem Statement and Goals for Active-Active Connection at
the Transparent Interconnection of Lots of Links (TRILL) Edge",
RFC 7379, October 2014, <http://www.rfc-
editor.org/info/rfc7379>.
[rfc6439bis] - Eastlake, D., et al., "TRILL: Appointed Forwarders",
draft-eastlake-trill-rfc6439bis, work in progress.
D. Eastlake, et al [Page 45]
INTERNET-DRAFT TRILL: Clarifications, Corrections, and Updates
Acknowledgements
The contributions of the following individuals to this document are
gratefully acknowledged:
Santosh Rajagopalan, Gayle Noble
The contributions of the following, listed in alphabetic order, to
the preceding version of this document, [RFC7180], are gratefully
acknowledged:
Somnath Chatterjee, Weiguo Hao, Rakesh Kumar, Yizhou Li, Radia
Perlman, Mike Shand, Meral Shirazipour, and Varun Shah.
The document was prepared in raw nroff. All macros used were defined
within the source file.
D. Eastlake, et al [Page 46]
INTERNET-DRAFT TRILL: Clarifications, Corrections, and Updates
Appendix A: Life Cycle of a TRILL Switch Port (New)
The contents of this informational Appendix originated in
http://www.ietf.org/mail-archive/web/trill/current/msg06355.html
Question: Suppose we are developing a TRILL implementation to run on
different machines. Then what happens first? Is LSP flooding or
ESADI started first? -> Link state database creation -> Designated
RBridge election (How to set priority? any fixed process that
depends on user settings? ) -> etc. ?
Answer:
The first thing that happens on a port/link is any link set-up
that is needed. For example, on a PPP link [RFC6361], you need to
negotiate that you will be using TRILL. However, if you have
Ethernet links [RFC6325], which are probably the most common type,
there isn't any link set-up needed.
As soon as the port is set-up, it can ingress or egress native
frames if end-station service is being offered on that port.
Offering end-station service is the default; however, if the port
trunk bit (end-station service disable) is set or the port is
configured as an IS-IS point-to-point link port, then end-station
service is not offered so native frames received are ignored and
native frames are not egressed.
Then TRILL IS-IS Hellos get sent out the port to be exchanged with
any other TRILL switches on the link [RFC7177]. Optionally, you
might also exchange MTU-probe/ack PDUs [RFC7177], BFD PDUs
[RFC7175], or other link test packets. But all these other things
are optional. Only Hellos are required.
TRILL doesn't send any TRILL Data or TRILL IS-IS packets out the
port to the link except Hellos until the link gets to the Two Way
or Report state [RFC7177].
If a link is configured as a point-to-point link, there is no
Designated RBridge (DRB) election. By default, an Ethernet link is
considered a LAN link and the DRB election occurs when the link is
in any state other than Down. You don't have to configure
priorities for each TRILL switch (RBridge) to be Designated
RBridge (DRB). Things will work fine with all the RBridges on a
link using default priority. But if the network manager wants to
control this, there should be a way for them to configure the
priority to be DRB of the TRILL switch ports on the link.
(To avoid complexity, this appendix generally describes things for
a link that only has two TRILL switches on it. But TRILL works
fine as currently specified on a broadcast link with multiple
D. Eastlake, et al [Page 47]
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TRILL switches on it, actually multiple TRILL switch ports, since
a TRILL switch can have multiple ports connected to the same link.
The most likely way to get such a multi-access link with current
technology and the existing TRILL standards is to have more than 2
TRILL switch Ethernet ports connected to a bridged LAN. Since the
TRILL protocol operates above all bridging, to the first
approximation the bridge LAN looks like a transparent broadcast
link to TRILL.)
When a link gets to the 2-Way or Report state, then LSP, CSNP, and
PSNP PDUs start to flow on the link (as well as FS-LSPs, FS-CSNPs,
and FS-PSNPs for E-L1FS (see Section 8.1)).
When a link gets to the Report state, then there is adjacency. The
existence of that adjacency is flooded (reported) to the campus in
LSPs. TRILL Data packets can then start to flow on the link as
TRILL switches recalculate the least cost paths and distribution
trees to take the new adjacency into account. Until it gets to the
Report state, there is no adjacency and no TRILL Data packets can
flow over that link (with the minor corner case exception that an
RBridge Channel message can, for its first hop only, be sent on a
port where there is no adjacency (Section 2.4 of [RFC7178]).
(Although this paragraph seems to be talking about link state, it
is actually port state. It is possible for different TRILL switch
ports on the same link to temporarily be in different states. The
adjacency state machinery runs independently on each port.)
ESADI [RFC7357] is built on top of the regular TRILL Data routing.
Since ESADI PDUs look, to transit TRILL switches, like regular
TRILL Data packets, no ESADI PDUs can flow until adjacencies are
established and TRILL Data is flowing. Of course, ESADI is
optional and is not used unless configured...
Question: Does it require TRILL Full headers at the time TRILL-LSPs
start being broadcast on a link? Because at that time it's not
defined Egress and Ingress nicknames.
Answer:
TRILL Headers are only for TRILL Data packets. TRILL IS-IS
packets, such as TRILL-LSPs, are sent in a different way that does
not use a TRILL Header and does not depend on nicknames.
Probably, in most implementations, a TRILL switch will start up
using the same nickname it had when it shut down or last got
disconnected from a campus. If you want, you can implement TRILL
to come up initially not reporting any nickname (by not including
an Nickname sub-TLV in its LSPs) until you get the link state
database or most of the link state database, and then choose a
nickname no other TRILL switch in the campus is using. Of course,
D. Eastlake, et al [Page 48]
INTERNET-DRAFT TRILL: Clarifications, Corrections, and Updates
if a TRILL switch does not have a nickname, then it cannot ingress
data, cannot egress known unicast data, and cannot be a tree root.
TRILL IS-IS PDUs such as LSPs, and the link state database, all
work based on the 7-byte IS-IS System-ID (sometimes called the LAN
ID [IS-IS]). System-IDs always have to be unique across the campus
so there is no problem determining topology regardless of nickname
state. The Nickname system is built on top of that.
D. Eastlake, et al [Page 49]
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Appendix B: Example TRILL PDUs (New)
This appendix gives example TRILL IS-IS PDUs. The primary purpose of
these examples is to clarify bit ordering issues.
B.1 LAN Hello over Ethernet
A TRILL Hello sent from a TRILL switch (RBridge) with 7-byte System
ID 0x30033003300300 holding nickname 0xFFDE over Ethernet from a port
with MAC address 0x00005E0053DE on VLAN 1 at priority 7. There is one
neighbor that is DRB. The neighbor's port MAC is 0x00005E0053E3 and
the neighbor's System ID is 0x44444444444400.
Ethernet Header
Outer.MacDA, Outer.MacSA
0x0180C2000041 All-IS-IS-RBridges Dest. MAC Addr.
0x00005E0053DE Source MAC Address
Outer VLAN Tag (optional)
0x8100 C-VLAN Ethertype [802.1Q]
0xE001 Priority 7, Outer.VLAN
IS-IS
0x22F4 L2-IS-IS Ethertype
IS-IS Payload
Common Header
0x83 Interdomain Routeing Discriminator
0x08 Header Length
0x01 IS-IS Version Number
0x06 ID Length of 6 Octets
0x0F PDU Type (Level 1 LAN Hello)
0x01 Version
0x00 Reserved
0x01 Maximum Area Addresses
Hello PDU Specific Fields
0x01 Circuit Type (Level 1)
0x30033003300300 Source System ID
0x0009 Holding Time
0xXXXX PDU Length
0x40 Priority to be DRB
0x44444444444400 LAN ID
TLVs (the below order of TLVs or of sub-TLVs in a TLV
is not significant.
Area Addresses TLV
0x01 Area Addresses Type
0x02 Length of Value
0x01 Length of Address
0x00 The fixed TRILL Area Address
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MT Port Capabilities TLV
0x8F MT Port Capabilities Type
0x0011 Length of Value
0x0000 Topology
Special VLANs and Flags Sub-TLV
0x01 Sub-TLV Type
0x08 Length
0x0123 Port ID
0xFFDE Sender Nickname
0x0001 Outer.VLAN
0x0001 Designated VLAN
Enabled VLANs sub-TLV (optional)
0x02 Sub-TLV Type
0x03 Length
0x0001 Start VLAN 1
0x80 VLAN 1
TRILL Neighbor TLV
0x91 Neighbor Type
0x0A Length of Value
0xC0 S & L Flags = 1, SIZE field 0
NEIGHBOR RECORD
0x00 Flags
0x2328 MTU = 9K bytes
0x00005E0053E3 Neighbor MAC Address
Scoped Flooding Support TLV
0xF3 Scoped Flooding Support Type
0x01 Length of Value
0x40 E-L1FS Flooding Scope
More TLVs (optional)
...
Ethernet Trailer
0xXXXXXXXX Ethernet Frame Check Sequence
B.2 LSP Over PPP
Here is an example of a TRILL LSP PDU sent over a PPP link by the
same source TRILL switch as the example in B.1.
PPP Header
0x405D PPP TRILL Link State Protocol
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IS-IS Payload
Common Header
0x83 Interdomain Routeing Discriminator
0x08 Header Length
0x01 IS-IS Version Number
0x06 ID Length of 6 Octets
0x12 PDU Type (Level 1 LSP)
0x01 Version
0x00 Reserved
0x01 Maximum Area Addresses
LSP Specific Fields
0xXXXX PDU Length
0x0123 Remaining Lifetime
0x3003300330030009 LSP ID (fragment 9)
0x00001234 Sequence Number
0xXXXX Checksum
0x01 Flags = Level 1
TLVs (the below order of TLVs or of sub-TLVs in a TLV
is not significant.
Router Capability TLV
0xF2 Router Capability Type
0x0F Length of Value
0x00 Flags
Nickname Sub-TLV
0x06 Sub-TLV Type
0x05 Length of Value
NICKNAME RECORD
0x33 Nickname Priority
0x1234 Tree Root Priority
0xFFDE Nickname
TRILL Version Sub-TLV
0x0D Sub-TLV Type
0x05
0x00 Max Version
0x40000000 Flags = FGL Support
More TLVs (optional
...
PPP Trailer
0xXXXXXX PPP Frame Check Sequence
B.3 TRILL Data Over Ethernet
Below is an IPv4 ICMP Echo [RFC792] sent in a TRILL Data packet from
the TRILL switch that sent the Hello in B.1 to the neighbor TRILL
switch on the link used in B.1.
D. Eastlake, et al [Page 52]
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Ethernet Header
Outer.MacDA, Outer.MacSA
0x00005E0053E3 Destination MAC Address
0x00005E0053DE Source MAC Address
Outer VLAN Tag (optional)
0x8100 C-VLAN Ethertype [802.1Q]
0x0001 Priority 0, Outer.VLAN 1
TRILL
0x22F3 TRILL Ethertype
TRILL Header
0X000E Flags, Hop Count 14
0xFFDF Egress Nickname
0xFFDC Ingress Nickname
Inner Ethernet Header
Inner.MacDA, Inner.MacSA
0x00005E005322 Destination Mac Address
0x00005E005344 Source Mac Address
Inner VLAN Tag
0x8100 C-VLAN Ethertype
0x0022 Priority 0, Inner.VLAN 34
Ethertype
0x0800 IPv4 Ethertype
IP Header
0x4500 Version 4, Header Length 5, ToS 0
0xXXXX Total Length
0x3579 Identification
0x0000 Flags, Fragment Offset
0x1101 TTL 17, ICMP = Protocol 1
0xXXXX Header Checksum
0xC0000207 Source IP 192.0.2.7
0xC000020D Destination IP 192.0.2.13
0x00000000 Options, Padding
ICMP
0x0800 ICMP Echo
0xXXXX Checksum
0x87654321 Identifier, Sequence Number
... Echo Data
Ethernet Trailer
0xXXXXXXXX Ethernet Frame Check Sequence
B.4 TRILL Data Over PPP
Below is an ARP [RFC826] sent in a TRILL Data packet from the TRILL
switch that sent the Hello in B.1 over a PPP link.
PPP Header
0x005D PPP TRILL Network Protocol
D. Eastlake, et al [Page 53]
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TRILL Header
0X080D Flags (M=1), Hop Count 13
0xFFDD Distribution Tree Root Nickname
0xFFDC Ingress Nickname
Inner Ethernet Header
Inner.MacDA, Inner.MacSA
0xFFFFFFFFFFFF Destination Mac Address
0x00005E005344 Source Mac Address
Inner VLAN Tag
0x8100 C-VLAN Ethertype
0x0022 Priority 0, Inner.VLAN 34
Ethertype
0x0806 ARP Ethertype
ARP
0x0001 Hardware Address Space = Ethernet
0x0001 Protocol Address Space = IPv4
0x06 Size of Hardware Address
0x04 Size of Protocol Address
0x0001 OpCode = Request
0x00005E005344 Sender Hardware Address
0xC0000207 Sender Protocol Address 192.0.2.7
0x000000000000 Target Hardware Address
0xC000020D Target Protocol Address 192.0.2.13
PPP Trailer
0xXXXXXX PPP Frame Check Sequence
D. Eastlake, et al [Page 54]
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Appendix C: Changes to Previous RFCs (New)
C.1 Changes to Obsoleted [RFC7180]
This section summarizes the changes, augmentations, and excisions
this document makes to [RFC7180] which it obsoletes and replaces.
C.1.1 Changes
For each heading in this document ending with "(Changed)", this
section summarizes how it was changed:
Section 1, Introduction: numerous changes to reflect the overall
changes in contents.
Section 1.1, Precedence: changed to add mention of [RFC7179].
Section 1.3, Terminology and Acronyms: numerous terms added.
Section 3, Distribution Trees and RPF Check: changed by the addition
of the new material in Section 3.6. See C.1.2 item 1.
Section 8, Other IS-IS Considerations: Changed by the addition of
Sections 8.1, 8.2, 8.3, and 8.4. See Appendix C.1.2 items 2, 3, 4,
and 5 respectively.
Section 9, Updates to [RFC7177] (Adjacency): Changes and additions to
[RFC7177] to support E-L1FS. See Appendix C.1.2, item 2.
Section 12, IANA Considerations: changed by the addition of material
in Section 12.2. See Appendix C.1.2, item 7.
Section 13, Security Considerations: minor changes in the RFCs
listed.
C.1.2 Additions
The following material was added to [RFC7180] in producing this
document:
D. Eastlake, et al [Page 55]
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1. Addition of support for an alternative Reverse Path Forwarding
Check (RPFC) along with considerations for deciding between the
original [RFC6325] RPFC and this alternative RPFC. This
alternative RPFC was originally discussed on the TRILL WG mailing
list in http://www.ietf.org/mail-
archive/web/trill/current/msg01852.html and subsequent messages.
(Section 3.6)
2. Addition of mandatory E-L1FS [RFC7356] support (Section 8.1,
Section 9).
3. Recommendations concerning control packet priorities. (Section
8.2)
4. Implementation requirements concerning unknown IS-IS PDU types
(Section 8.3).
5. Specification of an optional Nickname Flags APPsub-TLV and an
ingress flag within that APPsub-TLV. (Section 8.4)
6. Update TRILL Header to allocate a Color bit (Section 10.1) and
update the optional TRILL Header Extension Flag Word to allocate
a two-bit Extended Color field (Section 10.2).
7. Some new IANA Considerations in Section 12.2 including
reservation of nicknames for use as examples in documentation.
8. Section 11 on the Appointed Forwarder Status Lost Counter,
loosening mandatory update requirements in [rfc6325].
9. Informative Appendix A on the Lifecycle of a TRILL Port.
10. Add Appendix B with example TRILL PDUs.
11. Add recommendation to use Purge Originator Identification TLV.
(Section 8.6)
C.1.3 Deletions
The following material was deleted from [RFC7180] in producing this
document:
1. Removal of all updates to [RFC6327] that occurred in [RFC7180].
These have been rolled into [RFC7177] that obsoletes [RFC6327].
However, new updates to [RFC7177] are included (see Item 1 in
Section A.1).
2. Removal of all updates to [RFC6439]. These have been rolled into
D. Eastlake, et al [Page 56]
INTERNET-DRAFT TRILL: Clarifications, Corrections, and Updates
[rfc6439bis] that obsoletes [RFC6439].
C.2 Changes to [RFC6325]
This document contains many normative changes to [RFC6325], some of
which were in [RFC7180] that it replaces, including the following:
1. Change nickname allocation to ignore conflicts with data-
unreachable RBridges.
2. Fix errors: [Err3002] [Err3003] [Err3004] [Err3052] [Err3053]
[Err3508].
3. Change for the requirement to use the RPF check in [RFC6325] for
multi-destination TRILL Data packets by providing an alternative
stronger RPF check.
4. Adoption of the change of the CFI bit, which was required to be
zero in the inner frame, to the DEI bit which is obtained from
inner frame ingress or creation.
5. Require all RBridge to support E-L1FS FS-LSPs flooding.
6. The variable length TRILL Header extensions area is reduced to one
optional flags word and the extensions length field reduced to one
bit indicated that the flag word is present with the rest of the
length field now reserved.
7. Change the mandatory Appointed Forwarder Status Lost Counter
increment provisions as specified in Section 11.
C.3 Changes to [RFC7177]
All of the updates to [RFC7177] herein are in Section 9. Basically,
this document requires a Scoped Flooding Support TLV [RFC7356] to
appear in all Hellos and that TRILL switches retain in their
adjacency state the information received in that TLV.
C.4 Changes to [RFC7179]
The updates to [RFC7179] herein are in Sections 10.2 and 10.3.
D. Eastlake, et al [Page 57]
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Appendix Z: Change History
This appendix lists version changes in this document.
RFC Ediotr: Please delete this Appendix before publicaton.
From -00 to -01:
1. Expand Appendix C to cover changes to RFC 6325, RFC 7177, and RFC
7179 as well as 7180 and add material to the Introduction on
changes or previous RFCs.
2. Add a paragraph just before the Section 8.1.1 header about the
uses of E-L1FS FS-LSPs, the size limit on E-L1FS fragment zero,
and handling of TRILL GENINFO TLVs.
3. At the end of Section 9, add item 5 updating Table 4 in [RFC7177].
4. In Section 12.2.3, add a Registry for NickFlags bits.
5. Add Section 12.2.6 assigning nicknames for use as examples in
documentation.
6. Small improvements to the Security Considerations section.
7. Augment and update references.
8. Add a bit to Appendix A and add a lot to Appendix B.
9. Minor editorial changes.
From -01 to -02
1. Add Section 8.6 on Purge Originator Identification TLV.
2. Update reference to IEEE Std 802.
3. Move Acknowledgements after References as this is now the RFC
Editor preference.
4. Numerous editorial fixes.
From -02 to -03
Updated for Shepherd comments. No technical change.
From -03 to -04
Update reference to draft-ietf-trill-oam-fm to be to [RFC7455].
D. Eastlake, et al [Page 58]
INTERNET-DRAFT TRILL: Clarifications, Corrections, and Updates
From -04 to -05
Fix typo at the beginning of Section 10 based on RTG Directorate
review.
From -05 to -06
Changes based on AD Review:
1. Move former Appendix C to be the new Section 11, renumbering
following sections and making corresponding updates.
2. Several editorial improvements.
From -06 to -07
Changes based on IESG review (which included GENART and SECDIR
reviews).
D. Eastlake, et al [Page 59]
INTERNET-DRAFT TRILL: Clarifications, Corrections, and Updates
Authors' Addresses
Donald Eastlake 3rd
Huawei Technology
155 Beaver Street
Milford, MA 01757 USA
Phone: +1-508-333-2270
EMail: d3e3e3@gmail.com
Mingui Zhang
Huawei Technologies
No. 156 Beiqing Rd. Haidian District,
Beijing 100095
P.R. China
EMail: zhangmingui@huawei.com
Radia Perlman
EMC
2010 256th Avenue NE, #200
Bellevue, WA 98007 USA
EMail: radia@alum.mit.edu
Ayan Banerjee
Cisco
EMail: ayabaner@cisco.com
Anoop Ghanwani
Dell
5450 Great America Parkway
Santa Clara, CA 95054 USA
EMail: anoop@alumni.duke.edu
Sujay Gupta
IP Infusion,
RMZ Centennial
Mahadevapura Post
Bangalore - 560048 India
EMail: sujay.gupta@ipinfusion.com
D. Eastlake, et al [Page 60]
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Copyright and IPR Provisions
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
D. Eastlake, et al [Page 61]
