Internet DRAFT - draft-ietf-trill-channel-tunnel
draft-ietf-trill-channel-tunnel
INTERNET-DRAFT Donald Eastlake
Updates: 7178 Huawei
Intended status: Proposed Standard Mohammed Umair
IPinfusion
Yizhou Li
Huawei
Expires: September 1, 2016 March 18, 2016
TRILL: RBridge Channel Tunnel Protocol
<draft-ietf-trill-channel-tunnel-08.txt>
Abstract
The IETF TRILL (Transparent Interconnection of Lots of Links)
protocol includes an optional mechanism (specified in RFC 7178),
called RBridge Channel, for the transmission of typed messages
between TRILL switches in the same campus and the transmission of
such messages between TRILL switches and end stations on the same
link. This document specifies two optional extensions to the RBridge
Channel protocol: (1) a standard method to tunnel a variety of
payload types by encapsulating them in an RBridge Channel message;
and (2) a method to support security facilities for RBridge Channel
messages. This document updates RFC 7178.
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 authors or 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."
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, M. Umair, & Y. Li [Page 1]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
Table of Contents
1. Introduction............................................3
1.1 Terminology and Acronyms..............................3
2. Channel Tunnel Packet Format............................5
3. Channel Tunnel Payload Types............................8
3.1 Null Payload...........................................8
3.2 Ethertyped Payload.....................................8
3.2.1 Tunneled RBridge Channel Message.....................9
3.2.2 Tunneled TRILL Data Packet...........................9
3.2.3 Tunneled TRILL IS-IS Packet.........................10
3.3 Ethernet Frame........................................11
4. Security, Keying, and Algorithms.......................14
4.1 Basic Security Information Format.....................14
4.2 Authentication and Encryption Coverage................15
4.3 Derived Keying Material...............................17
4.4 SType None............................................17
4.5 RFC 5310 Based Authentication.........................17
4.6 DTLS Pairwise Security................................18
5. Channel Tunnel Errors..................................20
5.1 SubERRs under ERR 6...................................20
5.2 Secure Nested RBridge Channel Errors..................20
6. IANA Considerations....................................21
6.1 Channel Tunnel RBridge Channel Protocol Number........21
6.2 RBridge Channel Error Codes Subregistry...............21
7. Security Considerations................................22
Normative References......................................23
Informative References....................................24
Appendix Z: Change History................................25
Acknowledgements..........................................27
Authors' Addresses........................................28
D. Eastlake, M. Umair, & Y. Li [Page 2]
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1. Introduction
The IETF TRILL base protocol [RFC6325] [RFC7780] has been extended
with the RBridge Channel [RFC7178] facility to support transmission
of typed messages (for example BFD (Bidirectional Forwarding
Detection) [RFC7175]) between two TRILL switches (RBridges) in the
same campus and the transmission of such messages between RBridges
and end stations on the same link. When sent between RBridges in the
same campus, a TRILL Data packet with a TRILL Header is used and the
destination RBridge is indicated by nickname. When sent between a
RBridge and an end station on the same link in either direction a
native RBridge Channel messages [RFC7178] is used with no TRILL
Header and with the destination port or ports are indicated by a MAC
address. (There is no mechanism to stop end stations on the same
link, from sending native RBridge Channel messages to each other;
however, such use is outside the scope of this document.)
This document updates [RFC7178] and specifies extensions to RBridge
Channel that provide two additional facilities as follows:
(1) A standard method to tunnel a variety of payload types by
encapsulating them in an RBridge Channel message.
(2) A method to provide security facilities for RBridge Channel
messages.
Use of each of these facilities is optional, except that if Channel
Tunnel is implemented there are two payload types that MUST be
implemented. Both of the above facilities can be used in the same
packet. In case of conflict between this document and [RFC7178], this
document takes precedence.
1.1 Terminology and Acronyms
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].
This document uses terminology and acronyms defined in [RFC6325] and
[RFC7178]. Some of these are repeated below for convenience along
with additional new terms and acronyms.
Data Label - VLAN or FGL.
DTLS - Datagram Transport Level Security [RFC6347].
FCS - Frame Check Sequence.
D. Eastlake, M. Umair, & Y. Li [Page 3]
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FGL - Fine Grained Label [RFC7172].
HKDF - Hash based Key Derivation Function [RFC5869].
IS-IS - Intermediate System to Intermediate Systems [IS-IS].
PDU - Protocol Data Unit.
RBridge - An alternative term for a TRILL switch.
SHA - Secure Hash Algorithm [RFC6234].
Sz - Campus wide minimum link MTU [RFC6325] [RFC7780].
TRILL - Transparent Interconnection of Lots of Links or Tunneled
Routing in the Link Layer.
TRILL switch - A device that implements the TRILL protocol
[RFC6325], sometimes referred to as an RBridge.
D. Eastlake, M. Umair, & Y. Li [Page 4]
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2. Channel Tunnel Packet Format
The general structure of an RBridge Channel message between two TRILL
switches (RBridges) in the same campus is shown in Figure 2.1 below.
The structure of a native RBridge Channel message sent between an
RBridge and an end station on the same link, in either direction, is
shown in Figure 2.2 and, compared with the first case, omits the
TRILL Header, inner Ethernet addresses, and Data Label. A Protocol
field in the RBridge Channel Header gives the type of RBridge Channel
message and indicates how to interpret the Channel Protocol Specific
Payload [RFC7178].
+-----------------------------------+
| Link Header |
+-----------------------------------+
| TRILL Header |
+-----------------------------------+
| Inner Ethernet Addresses |
+-----------------------------------+
| Data Label (VLAN or FGL) |
+-----------------------------------+
| RBridge Channel Header |
+-----------------------------------+
| Channel Protocol Specific Payload |
+-----------------------------------+
| Link Trailer (FCS if Ethernet) |
+-----------------------------------+
Figure 2.1 RBridge Channel Packet Structure
+-----------------------------------+
| Ethernet Link Header |
+-----------------------------------+
| RBridge Channel Header |
+-----------------------------------+
| Channel Protocol Specific Payload |
+-----------------------------------+
| FCS |
+-----------------------------------+
Figure 2.2 Native RBridge Channel Frame
The RBridge Channel Header looks like this:
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1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x8946 | CHV=0 | Channel Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ /
/ Channel Protocol Specific Data /
/-+-+-+-+-+- /
Figure 2.3 RBridge Channel Header
where 0x8946 is the RBridge Channel Ethertype and CHV is the Channel
Header Version. This document is based on RBridge Channel version
zero.
The extensions specified herein are in the form of an RBridge Channel
protocol, the Channel Tunnel Protocol. Figure 2.4 below expands the
RBridge Channel Header and Protocol Specific Payload above for the
case of the Channel Tunnel Protocol.
1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 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
RBridge Channel Header:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x8946 | CHV=0 | Tunnel Protocol = TBD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Channel Tunnel Protocol Specific: | SubERR| RESV4 | SType | PType |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Security Information, variable length (0 length if SType = 0) /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
| Tunneled Data, variable length
| ...
Figure 2.4 Channel Tunnel Header Structure
The RBridge Channel Header field specific to the RBridge Channel
Tunnel Protocol is the Protocol field. Its contents MUST be the value
allocated for this purpose (see Section 6).
The RBridge Channel Tunnel Protocol Specific Data fields are as
follows:
SubERR: This field provides further details when a Channel Tunnel
error is indicated in the RBridge Channel ERR field. If ERR is
zero, then SubERR MUST be sent as zero and ignored on receipt.
See Section 5.
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RESV4: This field MUST be sent as zero. If non-zero when received,
this is an error condition (see Section 5).
SType: This field describes the type of security information and
features, including keying material, being used or provided by
the Channel Tunnel packet. See Section 4.
PType: Payload type. This describes the tunneled data. See Section
3 below.
Security Information: Variable length information. Length is zero
if SType is zero. See Section 4.
The Channel Tunnel protocol is integrated with the RBridge Channel
facility. Channel Tunnel errors are reported as if they were RBridge
Channel errors, using newly allocated code points in the ERR field of
the RBridge Channel Header supplemented by the SubERR field.
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3. Channel Tunnel Payload Types
The Channel Tunnel Protocol can carry a variety of payloads as
indicated by the PType field. Values are shown in the table below
with further explanation after the table.
PType Section Description
----- ------- -----------
0 Reserved
1 3.1 Null
2 3.2 Ethertyped Payload
3 3.3 Ethernet Frame
4-14 Unassigned
15 Reserved
Table 3.1 Payload Type Values
While implementation of the Channel Tunnel protocol is optional, if
it is implemented PType 1 (Null) MUST be implemented and PType 2
(Ethertyped Payload) with the RBridge Channel Ethertype MUST be
implemented. PType 2 for any Ethertypes other than the RBridge
Channel Ethertype MAY be implemented. PType 3 MAY be implemented.
The processing of any particular Channel Protocol message and its
payload depends on meeting local security and other policy at the
destination TRILL switch or end station.
3.1 Null Payload
The Null payload type (PType = 1) is intended to be used for testing
or for messages such as key negotiation or the like where only
security information is present. It indicates that there is no
payload. Any data after the Security Information field is ignored. If
the Channel Tunnel feature is implemented, Null Payload MUST be
supported in the sense that an "Unsupported PType" error is not
returned (see Section 5). Any particular use of the Null Payload
should specify what VLAN or priority should be used when relevant.
3.2 Ethertyped Payload
A PType of 2 indicates that the payload of the Channel Tunnel message
begins with an Ethertype. A TRILL switch supporting the Channel
Tunnel protocol MUST support a PType of 2 with a payload beginning
with the RBridge Channel Ethertype as describe in Section 3.2.1.
Other Ethertypes, including the TRILL and L2-IS-IS Ethertypes as
described in Section 3.2.2 and 3.2.3, MAY be supported.
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3.2.1 Tunneled RBridge Channel Message
A PType of 2 with an initial RBridge Channel Ethertype indicates an
encapsulated RBridge Channel message payload. A typical reason for
sending an RBridge Channel message inside a Channel Tunnel message is
to provide security services, such as authentication or encryption.
This payload type looks like the following:
1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | CHV=0 | Tunnel Protocol = TBD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR | SubERR| RESV4 | SType | 0x2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Security Information, variable length (0 length if SType = 0) /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | CHV=0 |Nested Channel Protocol|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Nested Channel Protocol Specific Data ... /
/ /
Figure 3.1 Tunneled RBridge Channel Message Structure
3.2.2 Tunneled TRILL Data Packet
A PType of 2 and an initial TRILL Ethertype indicates that the
payload of the Tunnel protocol message is an encapsulated TRILL Data
packet as shown in the figure below. If this Ethertype is supported
for PType = 2 and the message meets local policy for acceptance, the
tunneled TRILL Data packet is handled as if it had been received by
the destination TRILL switch on the port where the Channel Tunnel
message was received.
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1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | CHV=0 | Tunnel Protocol = TBD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR | SubERR| RESV4 | SType | 0x2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Security Information, variable length (0 length if SType = 0) /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TRILL (0x22F3) | V |A|C|M| RESV |F| Hop Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Egress Nickname | Ingress Nickname |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Optional Flags Word /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner.MacDA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner.MacDA continued | Inner.MacSA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner.MacSA (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Inner Data Label (2 or 4 bytes)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
| TRILL Data Packet payload
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
Figure 3.2 Nested TRILL Data Packet Channel Tunnel Structure
The optional flags word is only present if the F bit in the TRILL
Header is one [RFC7780].
3.2.3 Tunneled TRILL IS-IS Packet
A PType of 2 and an initial L2-IS-IS Ethertype indicates that the
payload of the Tunnel protocol message is an encapsulated TRILL IS-IS
PDU as shown in Figure 3.3. If this Ethertype is supported for PType
= 2, the tunneled TRILL IS-IS packet is processed by the destination
RBridge if it meets local policy. One possible use is to expedite the
receipt of a link state PDU (LSP) by some TRILL switch or switches
with an immediate requirement for the link state information. A link
local IS-IS PDU (Hello, CSNP, or PSNP [IS-IS]; MTU-probe or MTU-ack
[RFC7176]; or circuit scoped FS-LSP, FS-CSNP or FS-PSNP [RFC7356])
would not normally be sent via this Channel Tunnel method except
possibly to encrypt it since such PDUs can just be transmitted on the
link and do not normally need RBridge Channel tunneling.
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1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | CHV=0 | Tunnel Protocol = TBD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR | SubERR| RESV4 | SType | 0x2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Security Information, variable length (0 length if SType = 0) /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
| L2-IS-IS (0x22F4) | 0x83 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| rest of IS-IS PDU
+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
Figure 3.3 Tunneled TRILL IS-IS Packet Structure
3.3 Ethernet Frame
If PType is 3, the Tunnel Protocol payload is an Ethernet frame as
might be received from or sent to an end station except that the
tunneled Ethernet frame's FCS is omitted, as shown in Figure 3.4.
(There is still an overall final FCS if the RBridge Channel message
is being sent on an Ethernet link.) If this PType is implemented and
the message meets local policy, the tunneled frame is handled as if
it had been received on the port on which the Channel Tunnel message
was received.
The priority of the RBridge Channel message can be copied from the
Ethernet frame VLAN tag, if one is present, except that priority 7
SHOULD only be used for messages critical to establishing or
maintaining adjacency and priority 6 SHOULD only be used for other
important control messages.
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1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RBridge-Channel (0x8946) | 0x0 | Tunnel Protocol = TBD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | ERR | SubERR| RESV4 | SType | 0x3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ Security Information, variable length (0 length if SType = 0) /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MacDA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MacDA (cont.) | MacSA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MacSA (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Any Ethernet frame tagging...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
| Ethernet frame payload...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
Figure 3.4 Ethernet Frame Channel Tunnel Structure
In the case of a non-Ethernet link, such as a PPP (Point-to-Point
Protocol) link [RFC6361], the ports on the link are considered to
have link local synthetic 48-bit MAC addresses constructed as
described below. These constructed addresses MAY be used as a MacSA.
If the RBridge Channel message is link local, the source TRILL switch
will have the information to construct such a MAC address for the
destination TRILL switch port and that MAC address MAY be used as the
MacDA. By the use of such a MacSA and either such a unicast MacDA or
a group addressed MacDA, an Ethernet frame can be sent between two
TRILL switch ports connected by a non-Ethernet link.
These synthetic TRILL switch port MAC addresses for non-Ethernet
ports are constructed as follows: 0xFEFF, the nickname of the TRILL
switch used in TRILL Hellos sent on that port, and the Port ID that
the TRILL switch has assigned to that port, as shown in Figure 3.5.
(Both the Port ID of the port on which a TRILL Hello is sent and the
nickname of the sending TRILL switch appear in the Special VLANs and
Flags sub-TLV [RFC7176] in TRILL IS-IS Hellos.) The resulting MAC
address has the Local bit on and the Group bit off [RFC7042].
However, since there will be no Ethernet end stations on a non-
Ethernet link in a TRILL campus, such synthetic MAC addresses cannot
conflict on the link with a real Ethernet port address.
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1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0xFEFF | Nickname |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3.5 Synthetic MAC Address
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4. Security, Keying, and Algorithms
Table 4.1 below gives the assigned values of the SType field and
their meaning. Use of DTLS Pairwise Security (SType = 2) is
RECOMMENDED. While [RFC5310] based authentication applies to both
pairwise and multi-destination traffic, it provides only
authentication and is generally considered not to met current
security standards, as it does not provide for key negotiation; thus,
its use is NOT RECOMMENDED.
Channel Tunnel DTLS based security specified in Section 4.6 below is
intended for pairwise (known unicast) use in which case the M bit in
the TRILL Header would be zero and in the native RBridge Channel case
(Figure 2.2) the Outer.MacDA would be individually addressed.
Multi-destination Channel Tunnel packets would be those with the M
bit in the TRILL Header set to one or, in the native RBridge Channel
case, the Outer.MacDA would be group addressed. However, the DTLS
Pairwise Security SType can be used in the multi-destination case by
serially unicasting the messages to all data accessible RBridges (or
end stations in the native RBridge Channel case) in the recipient
group. For TRILL Data packets, that group is specified by the Data
Label; for native frames, the group is specified by the groupcast
destination MAC address. It is intended to specify a true group keyed
SType to secure multi-destination packets in a separate document
[GroupKey].
SType Section Meaning
----- ------- -------
0 4.4 None
1 4.5 [RFC5310] Based Authentication
2 4.6 DTLS Pairwise Security
3-14 Available for assignment by IETF Review
15 Reserved
Table 4.1 SType Values
4.1 Basic Security Information Format
When SType is zero, there is no Security Information after the
Channel Tunnel header and before the payload. For all SType values
except zero, the Security Information starts with four reserved flag
bits and twelve bits of remaining length as follows:
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
| RESV | Size | More Info
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-...
Figure 4.1 Security Information Format
The fields are as follows:
RESV: Four reserved bits that MUST be sent as zero and ignored on
receipt. In the future, meanings may be assigned to these bits and
those meanings may differ for different STypes.
Size: The number of bytes, as an unsigned integer, of More Info in
the Security Information after the Size byte itself. Thus the
maximum possible length of Security Information is 4,097 bytes for
a Size of 4,095 plus 2 for the RESV and Size fields.
More Info: Additional Security Information of length Size. Contents
depends on the SType.
4.2 Authentication and Encryption Coverage
As show in Figure 4.2, the area covered by Channel Tunnel
authentication starts with the byte immediately after the TRILL
Header optional Flag Word if it is present. Otherwise, it starts
after the TRILL Header Ingress Nickname. In either case, it extends
to just before the TRILL Data packet link trailer. For example, for
an Ethernet packet it would extend to just before the FCS.
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+-----------------------------+
| Link Header |
+-----------------------------+
| TRILL Header |
| (plus optional flag word) |
+-----------------------------+ ^
| Inner Ethernet Addresses | | <-authentication
+-----------------------------+ .
| Data Label (VLAN or FGL) | |
+-----------------------------+ .
| RBridge Channel Header | |
+-----------------------------+ .
| Channel Tunnel Header | |
| (Security Information) | .
+-----------------------------+ | ^
| Payload | . | <-encryption
+-----------------------------+ v v
| Link Trailer |
+-----------------------------+
Figure 4.2. Channel Tunnel Security Coverage
Channel Tunnel authentication in the native RBridge Channel case (see
Figure 4.3), is as specified in the above paragraph except that it
starts with the RBridge Channel Ethertype, since there is no TRILL
Header, inner Ethernet addresses, or inner Data Label.
+-----------------------------+
| Ethernet Header |
+-----------------------------+ ^
| RBridge Channel Header | | <-authentication
+-----------------------------+ .
| Channel Tunnel Header | |
| (plus Security Information)| .
+-----------------------------+ | ^
| Payload | . | <-encryption
+-----------------------------+ v v
| Ethernet Trailer |
+-----------------------------+
Figure 4.3. Native Channel Tunnel Security Coverage
If an authentication value is included in the More Info field shown
in Section 4.1, it is treated as zero when authentication is
calculated. If an authentication value is included in a payload after
the security information, it is calculated as provided by the SType
and security algorithms in use.
If encryption is provided, it covers the payload from right after the
Channel Tunnel header Security Information through to just before the
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TRILL Data packet link trailer (see Figures 4.2 and 4.3).
4.3 Derived Keying Material
In some cases, it is possible to use material derived from [RFC5310]
IS-IS keying material as an element of Channel Tunnel security. In
such cases, the More Info field shown in Figure 4.1 includes the two
byte IS-IS Key ID to identify the keying material. It is assumed that
the IS-IS keying material is of high quality. The material actually
used in Channel Tunnel security is derived from the IS-IS keying
material as follows:
Derived Material =
HKDF-Expand-SHA256 ( IS-IS-key, "Channel Tunnel" | 0x0S, L )
where "|" indicates concatenation, HKDF is as in [RFC5869], SHA256 is
as in [RFC6234], IS-IS-key is the input IS-IS keying material,
"Channel Tunnel" is the 14-character ASCII [RFC20] string indicated
without any leading length byte or trailing zero byte, 0x0S is a
single byte where S is the SType for which this key derivation is
being used and the upper nibble is zero, and L is the length of
output-derived material needed.
Whenever IS-IS keying material is being used as above, the underlying
[RFC5310] keying material might expire or become invalidated. At the
time of or before such expiration or invalidation, the use Derived
Material from the IS-IS keying material MUST cease. Continued
security may depend on using new derived material from currently
valid [RFC5310] keying material.
4.4 SType None
No security services are being invoked. The length of the Security
Information field (see Figure 2.4) is zero.
4.5 RFC 5310 Based Authentication
The Security Information (see Figure 2.4) is the RESV and Size fields
specified in Section 4.1 with the value of the [RFC5310] Key ID and
Authentication Data, as shown in Figure 4.4.
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1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+
| Authentication Data (Variable)
+
|
+-+-+-+-+-+-+-+-+-+-+-+-+-...
Figure 4.4 SType 1 Security Information
o RESV: Four bits that MUST be sent as zero and ignored or receipt.
o Size: Set to 2 + the size of Authentication Data in bytes.
o Key ID: specifies the keying value and authentication algorithm
that the Key ID specifies for TRILL IS-IS LSP [RFC5310]
Authentication TLVs. The keying material actually used is derived
as shown in Section 4.3.
o Authentication Data: The authentication data produced by the
derived key and algorithm associated with the Key ID acting on the
packet as specified in Section 4.2. Length of the authentication
data depends on the algorithm.
While RBridges, which are IS-IS routers, can reasonable be expected
to hold [RFC5310] keying, so that this SType can be used for RBridge
Channel messages, how end stations might come to hold [rfc5310]
keying is beyond the scope of this document. Thus this SType might
not be applicable to native RBridge Channel messages.
4.6 DTLS Pairwise Security
DTLS supports key negotiation and provides both encryption and
authentication. The Channel Tunnel DTLS [RFC6347] SType uses a
negotiated DTLS version that MUST NOT be less than 1.2.
When DTLS pairwise security is used, the entire payload of the
Channel Tunnel packet, starting just after the Security Information
and ending just before the link trailer, is one or more DTLS records
[RFC6347]. As specified in [RFC6347], DTLS records MUST be limited
by the path MTU, in this case so each record fits entirely within a
single Channel Tunnel message. A minimum path MTU can be determined
D. Eastlake, M. Umair, & Y. Li [Page 18]
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from the TRILL campus wide minimum MTU Sz, which will not be less
than 1470 bytes, by allowing for the TRILL Data packet, Channel
Tunnel, and DTLS framing overhead. With this SType, the security
information provided before the DTLS record(s) is 0, as shown in
Figure 4.5, because all the security information is in the payload
area.
The DTLS Pairwise keying is set up between a pair of RBridges
independent of Data Label using messages of a priority configurable
at the RBridge level which defaults to priority 6. DTLS messages
other than application_data can be encapsulated in the Channel Tunnel
protocol with a TRILL Header using any Data Label. Actual
application_data sent with Channel Tunnel using this SType should use
the Data Label and priority as specified for that application_data.
The PType indicates the nature of the application_data.
TRILL switches that support the Channel Tunnel DTLS SType MUST
support the use of pre-shared keys for DTLS. If the psk_identity (see
[RFC4279]) is two bytes, it represents, as a pre-shared key to be
used in the DTLS negotiation, the value derived as shown in Section
4.3 from the key associated with that psk_identity as a [RFC5310] Key
ID. A psk_identity with a length other than two bytes MAY be used to
indicate other implementation dependent pre-shared keys.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RESV | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4.5 DTLS Channel Tunnel Security Info
TRILL switches that implement the Channel Tunnel DTLS SType MAY
support the use of certificates for DTLS but certificate size may be
limited by the DTLS requirement that each record fit within a single
message.
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5. Channel Tunnel Errors
RBridge Channel Tunnel Protocol errors are reported like RBridge
Channel level errors. The ERR field is set to one of the following
error codes:
ERR Meaning
--- ---------
6 Unknown or unsupported field value
7 Authentication failure
8 Error in nested RBridge Channel message
Table 5.1 Additional ERR Values
5.1 SubERRs under ERR 6
If the ERR field is 6, the SubERR field indicates the problematic
field or value as show in the table below.
SubERR Meaning (for ERR = 6)
------ ---------------------
0 Reserved
1 Non-zero RESV4 nibble
2 Unsupported SType
3 Unsupported PType
4 Unknown Key ID
5 Unknown Ethertype with PType = 2
Table 5.2 SubERR values under ERR 6
5.2 Secure Nested RBridge Channel Errors
If
a Channel Tunnel message is sent with security and with a payload
type (PType) indicating a nested RBridge Channel message
and
there is an error in the processing of that nested message that
results in a return RBridge Channel message with a non-zero ERR
field,
then that returned message SHOULD also be nested in an Channel Tunnel
message using the same type of security. In this case, the ERR field
in the Channel Tunnel envelope is set to 8 indicating that there is a
nested error in the message being tunneled back.
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6. IANA Considerations
This section lists IANA Considerations.
6.1 Channel Tunnel RBridge Channel Protocol Number
IANA is requested to assign TBD as the RBridge Channel protocol
number for the "Channel Tunnel" protocol from the range assigned by
Standards Action.
The added RBridge Channel protocols registry entry on the TRILL
Parameters web page is as follows:
Protocol Description Reference
-------- -------------- ------------------
TBD Channel Tunnel [this document]
6.2 RBridge Channel Error Codes Subregistry
IANA is requested to create a "RBridge Channel Error Codes"
subregistry under the "RBridge Channel Protocols" registry. The
header information is as follows:
Registration Procedures: IETF Review References: [RFC7178] [this
document]
The subregistry is to have columns and entries as follows:
Code Meaning Reference
---- ------- ---------
[populate rows for codes 0 through 5 from Section xxx of
[RFC7178] with reference [RFC7178] ]
[populate rows for codes 6 through 8 from Table 5.1 of this
document with reference [this document] ]
9-15 Unassigned
16 Reserved
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7. Security Considerations
The RBridge Channel Tunnel facility has potentially positive and
negative effects on security.
On the positive side, it provides optional security that can be used
to authenticate and/or encrypt RBridge Channel messages. Some RBridge
Channel message payloads, such as BFD [RFC7175], provide their own
security but where this is not true, consideration should be given,
when specifying an RBridge Channel protocol, to recommending or
requiring use of the security features of the Channel Tunnel
protocol.
On the negative side, the optional ability to tunnel various payload
types and to tunnel them between TRILL switches and to and from end
stations can increase risk unless precautions are taken. The
processing of decapsulating Tunnel Protocol payloads is not a good
place to be liberal in what you accept. This is because the tunneling
facility makes it easier for unexpected messages to pop up in
unexpected places in a TRILL campus due to accidents or the actions
of an adversary. Local policies should generally be strict and only
process payload types required and then only with adequate
authentication for the particular circumstances.
See the first paragraph of Section 4 for recommendations on SType
usage. See [RFC7457] for Security Considerations of DTLS for
security.
If IS-IS authentication is not being used, then [RFC5310] keying
information would not normally be available but that presumably
represents a judgment by the TRILL campus operator that no security
is needed.
See [RFC7178] for general RBridge Channel Security Considerations and
[RFC6325] for general TRILL Security Considerations.
D. Eastlake, M. Umair, & Y. Li [Page 22]
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Normative References
[IS-IS] - ISO/IEC 10589:2002, Second Edition, "Information technology
-- Telecommunications and information exchange between systems
-- 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)", 2002.
[RFC20] - Cerf, V., "ASCII format for network interchange", STD 80,
RFC 20, DOI 10.17487/RFC0020, October 1969, <http://www.rfc-
editor.org/info/rfc20>.
[RFC2119] - BBradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119,
March 1997, <http://www.rfc-editor.org/info/rfc2119>.
[RFC4279] - Eronen, P., Ed., and H. Tschofenig, Ed., "Pre-Shared Key
Ciphersuites for Transport Layer Security (TLS)", RFC 4279, DOI
10.17487/RFC4279, December 2005, <http://www.rfc-
editor.org/info/rfc4279>.
[RFC5310] - Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R.,
and M. Fanto, "IS-IS Generic Cryptographic Authentication", RFC
5310, DOI 10.17487/RFC5310, February 2009, <http://www.rfc-
editor.org/info/rfc5310>.
[RFC5869] - Krawczyk, H. and P. Eronen, "HMAC-based Extract-and-
Expand Key Derivation Function (HKDF)", RFC 5869, May 2010,
<http://www.rfc-editor.org/info/rfc5869>.
[RFC6325] - Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
Ghanwani, "Routing Bridges (RBridges): Base Protocol
Specification", RFC 6325, DOI 10.17487/RFC6325, July 2011,
<http://www.rfc-editor.org/info/rfc6325>.
[RFC6347] - Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, January 2012, <http://www.rfc-
editor.org/info/rfc6347>.
[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, DOI
10.17487/RFC7172, May 2014, <http://www.rfc-
editor.org/info/rfc7172>.
[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,
<http://www.rfc-editor.org/info/rfc7176>.
D. Eastlake, M. Umair, & Y. Li [Page 23]
INTERNET-DRAFT TRILL: RBridge Channel Tunnel
[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, DOI 10.17487/RFC7178, May
2014, <http://www.rfc-editor.org/info/rfc7178>.
[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>.
[RFC7780] - Eastlake 3rd, D., Zhang, M., Perlman, R., Banerjee, A.,
Ghanwani, A., and S. Gupta, "Transparent Interconnection of
Lots of Links (TRILL): Clarifications, Corrections, and
Updates", RFC 7780, DOI 10.17487/RFC7780, February 2016,
<http://www.rfc-editor.org/info/rfc7780>.
Informative References
[RFC6234] - Eastlake 3rd, D. and T. Hansen, "US Secure Hash
Algorithms (SHA and SHA-based HMAC and HKDF)", RFC 6234, DOI
10.17487/RFC6234, May 2011, <http://www.rfc-
editor.org/info/rfc6234>.
[RFC6361] - Carlson, J. and D. Eastlake 3rd, "PPP Transparent
Interconnection of Lots of Links (TRILL) Protocol Control
Protocol", RFC 6361, August 2011
[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.
[RFC7457] - Sheffer, Y., Holz, R., and P. Saint-Andre, "Summarizing
Known Attacks on Transport Layer Security (TLS) and Datagram
TLS (DTLS)", RFC 7457, February 2015, <http://www.rfc-
editor.org/info/rfc7457>.
[GroupKey] - D. Eastlake et al, "Group Keying Protocol", draft-ietf-
trill-group-keying, work in progress.
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Appendix Z: Change History
From -00 to -01
1. Fix references for RFCs published, etc.
2. Explicitly mention in the Abstract and Introduction that this
document updates [RFC7178].
3. Add this Change History Appendix.
From -01 to -02
1. Remove section on the "Scope" feature as mentioned in
http://www.ietf.org/mail-archive/web/trill/current/msg06531.html
2. Editorial changes to IANA Considerations to correspond to draft-
leiba-cotton-iana-5226bis-11.txt.
3. Improvements to the Ethernet frame payload type.
4. Other Editorial changes.
From -02 to -03
1. Update TRILL Header to correspond to [RFC7780].
2. Remove a few remnants of the "Scope" feature that was removed from
-01 to -02.
3. Substantial changes to and expansion of Section 4 including adding
details of DTLS security.
4. Updates and additions to the References.
5. Other minor editorial changes.
From -03 to -04
1. Add SType for [RFC5310] keying based security that provides
encryption as well as authentication.
2. Editorial improvements and fixes.
From -04 to -05
1. Primary change is collapsing the previous PTypes 2, 3, and 4 for
RBridge Channel message, TRILL Data, and TRILL IS-IS into one by
including the Ethertype. Previous PType 5 is renumbered as 3.
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2. Add Channel Tunnel Crypto Suites to IANA Considerations
3. Add some material to Security Considerations,
4. Assorted Editorial changes.
From -05 to -06
Fix editorials found during WG Last Call.
From -06 to -07
Minor editorial changes resulting for Shepherd review.
From -07 to -08
Move group keyed security out of the draft. Simplify and improve
remaining security provisions.
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Acknowledgements
The contributions of the following are hereby gratefully
acknowledged:
Susan Hares, Gayle Noble, Yaron Sheffer
The document was prepared in raw nroff. All macros used were defined
within the source file.
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Authors' Addresses
Donald E. Eastlake, 3rd
Huawei Technologies
155 Beaver Street
Milford, MA 01757 USA
Phone: +1-508-333-2270
EMail: d3e3e3@gmail.com
Mohammed Umair
IPinfusion
EMail: mohammed.umair2@gmail.com
Yizhou Li
Huawei Technologies
101 Software Avenue,
Nanjing 210012, China
Phone: +86-25-56622310
EMail: liyizhou@huawei.com
D. Eastlake, M. Umair, & Y. Li [Page 28]
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Copyright, Disclaimer, and Additional IPR Provisions
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D. Eastlake, M. Umair, & Y. Li [Page 29]
