Internet DRAFT - draft-ietf-forces-ceha
draft-ietf-forces-ceha
Network Working Group K. Ogawa
Internet-Draft NTT Corporation
Updates: 5810 (if approved) W. M. Wang
Intended status: Standards Track Zhejiang Gongshang University
Expires: June 13, 2014 E. Haleplidis
University of Patras
J. Hadi Salim
Mojatatu Networks
December 10, 2013
ForCES Intra-NE High Availability
draft-ietf-forces-ceha-10
Abstract
This document discusses Control Element High Availability within a
ForCES Network Element. Additionally this document updates [RFC5810]
by providing new normative text for the Cold-Standby High
availability mechanism.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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This Internet-Draft will expire on June 13, 2014.
Copyright Notice
Copyright (c) 2013 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
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publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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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.
Table of Contents
1. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Document Scope . . . . . . . . . . . . . . . . . . . . . 5
2.2. Quantifying Problem Scope . . . . . . . . . . . . . . . . 5
3. RFC5810 CE HA Framework . . . . . . . . . . . . . . . . . . . 6
3.1. RFC 5810 CE HA Support . . . . . . . . . . . . . . . . . 6
3.1.1. Cold Standby Interaction with ForCES Protocol . . . . 7
3.1.2. Responsibilities for HA . . . . . . . . . . . . . . . 10
4. CE HA Hot Standby . . . . . . . . . . . . . . . . . . . . . . 11
4.1. Changes to the FEPO model . . . . . . . . . . . . . . . . 11
4.2. FEPO processing . . . . . . . . . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
6. Security Considerations . . . . . . . . . . . . . . . . . . . 18
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.1. Normative References . . . . . . . . . . . . . . . . . . 19
7.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. New FEPO version . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29
1. Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
The following definitions are taken from [RFC3654], [RFC3746] and
[RFC5810]. They are repeated here for convenience as needed, but the
normative definitions are found in the referenced RFCs:
o Logical Functional Block (LFB) -- A template that represents a
fine-grained, logically separate aspects of FE processing.
o Forwarding Element (FE) - A logical entity that implements the
ForCES Protocol. FEs use the underlying hardware to provide per-
packet processing and handling as directed by a CE via the ForCES
Protocol.
o Control Element (CE) - A logical entity that implements the ForCES
Protocol and uses it to instruct one or more FEs on how to process
packets. CEs handle functionality such as the execution of
control and signaling protocols.
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o ForCES Network Element (NE) - An entity composed of one or more
CEs and one or more FEs. An NE usually hides its internal
organization from external entities and represents a single point
of management to entities outside the NE.
o FE Manager (FEM) - A logical entity that operates in the pre-
association phase and is responsible for determining to which
CE(s) an FE should communicate. This process is called CE
discovery and may involve the FE manager learning the capabilities
of available CEs.
o CE Manager - A logical entity that operates in the pre-association
phase and is responsible for determining to which FE(s) a CE
should communicate. This process is called FE discovery and may
involve the CE manager learning the capabilities of available FEs.
o ForCES Protocol -- The protocol used for communication
communication between CEs and FEs. This protocol does not apply
to CE-to-CE communication, FE-to-FE communication, or to
communication between FE and CE managers. The ForCES protocol is
a master-slave protocol in which FEs are slaves and CEs are
masters. This protocol includes both the management of the
communication channel (e.g., connection establishment, heartbeats)
and the control messages themselves.
o ForCES Protocol Layer (ForCES PL) -- A layer in the ForCES
protocol architecture that defines the ForCES protocol messages,
the protocol state transfer scheme, and the ForCES protocol
architecture itself (including requirements of ForCES TML as shown
below). Specifications of ForCES PL are defined in [RFC5810]
o ForCES Protocol Transport Mapping Layer (ForCES TML) -- A layer in
ForCES protocol architecture that specifically addresses the
protocol message transportation issues, such as how the protocol
messages are mapped to different transport media (like SCTP, IP,
TCP, UDP, ATM, Ethernet, etc), and how to achieve and implement
reliability, security, etc.
2. Introduction
Figure 1 illustrates a ForCES NE controlled by a set of redundant CEs
with CE1 being active and CE2 and CEN being a backup.
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-----------------------------------------
| ForCES Network Element |
| +-----------+ |
| | CEn | |
| | (Backup) | |
-------------- Fc | +------------+ +------------+ | |
| CE Manager |--------+-| CE1 |------| CE2 |-+ |
-------------- | | (Active) | Fr | (Backup) | |
| | +-------+--+-+ +---+---+----+ |
| Fl | | | Fp / | |
| | | +---------+ / | |
| | Fp| |/ |Fp |
| | | | | |
| | | Fp /+--+ | |
| | | +-------+ | | |
| | | | | | |
-------------- Ff | --------+--+-- ----+---+----+ |
| FE Manager |--------+-| FE1 | Fi | FE2 | |
-------------- | | |------| | |
| -------------- -------------- |
| | | | | | | | | |
----+--+--+--+----------+--+--+--+-------
| | | | | | | |
| | | | | | | |
Fi/f Fi/f
Fp: CE-FE interface
Fi: FE-FE interface
Fr: CE-CE interface
Fc: Interface between the CE Manager and a CE
Ff: Interface between the FE Manager and an FE
Fl: Interface between the CE Manager and the FE Manager
Fi/f: FE external interface
Figure 1: ForCES Architecture
The ForCES architecture allows FEs to be aware of multiple CEs but
enforces that only one CE be the master controller. This is known in
the industry as 1+N redundancy. The master CE controls the FEs via
the ForCES protocol operating on the Fp interface. If the master CE
becomes faulty, i.e. crashes or loses connectivity, a backup CE takes
over and NE operation continues. By definition, the current
documented setup is known as cold-standby. The set of CEs
controlling an FE is static and is passed to the FE by the FE Manager
(FEM) via the Ff interface and to each CE by the CE Manager (CEM) in
the Fc interface during the pre-association phase.
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From an FE perspective, the knobs of control for a CE set are defined
by the FEPO LFB in [RFC5810], Appendix B. In Section 3.1 of this
document we discuss further details of these knobs.
2.1. Document Scope
It is assumed that the reader is aware of the ForCES architecture to
make sense of the changes being described in this document. This
document provides background information to set the context of the
discussion in Section 4.
At the time this document is being written, the Fr interface is out
of scope for the ForCES architecture. However, it is expected that
organizations implementing a set of CEs will need to have the CEs
communicate to each other via the Fr interface in order to achieve
the synchronization necessary for controlling the FEs.
The problem scope addressed by this document falls into 2 areas:
1. To update the description of [RFC5810] with more clarity on how
current cold-standby approach operates within the NE cluster.
2. To describe how to evolve the [RFC5810] cold-standby setup to a
hot-standby redundancy setup to improve the failover time and NE
availability.
2.2. Quantifying Problem Scope
The NE recovery and availability is dependent on several time-
sensitive metrics:
1. How fast the CE plane failure is detected by the FE.
2. How fast a backup CE becomes operational.
3. How fast the FEs associate with the new master CE.
4. How fast the FEs recover their state, and become operational.
Each FE state is the collective state of all its instantiated
LFBs.
The design intent of the current [RFC5810] as well as this document
to meet the above goals are driven by desire for simplicity.
To quantify the above criteria with the current prescribed ForCES CE
setup in [RFC5810]:
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1. How fast the FE side detects a CE failure is left undefined. To
illustrate an extreme scenario, we could have a human operator
acting as the monitoring entity to detect faulty CEs. How fast
such detection happens could be in the range of seconds to days.
A more active monitor on the Fp interface could improve this
detection. Usually the FE will detect a CE failure either by the
TML if the Fp interface terminates or by the ForCES Protocol by
utilizing the ForCES heartbeat mechanism.
2. How fast the backup CE becomes operational is also currently out
of scope. In the current setup, a backup CE need not be
operational at all (for example, to save power) and therefore it
is feasible for a monitoring entity to boot up a backup CE after
it detects the failure of the master CE. In this document
Section 4 we suggest that at least one backup CE be online so as
to improve this metric.
3. How fast an FE associates with new master CE is also currently
undefined. The cost of an FE connecting and associating adds to
the recovery overhead. As mentioned above we suggest having at
least one backup CE online. In Section 4 we propose to zero out
the connection and association cost on failover by having each FE
associate with all online backup CEs after associating to an
active/master CE. Note that if an FE pre-associates with at
least one backup CE, then the system will be technically
operating in hot-standby mode.
4. And last: How fast an FE recovers its state depends on how much
NE state exists. By ForCES current definition, the new master CE
assumes zero state on the FE and starts from scratch to update
the FE. So the larger the state, the longer the recovery.
3. RFC5810 CE HA Framework
To achieve CE High Availability (HA), FEs and CEs MUST inter-operate
per [RFC5810] definition which is repeated for contextual reasons in
Section 3.1. It should be noted that in this default setup, which
MUST be implemented by CEs and FEs requiring HA, the Fr plane is out
of scope (and if available is proprietary to an implementation).
3.1. RFC 5810 CE HA Support
As mentioned earlier, although there can be multiple redundant CEs,
only one CE actively controls FEs in a ForCES NE. In practice there
may be only one backup CE. At any moment in time, only one master CE
can control an FE. In addition, the FE connects and associates to
only the master CE. The FE and the CE are aware of the primary and
one or more secondary CEs. This information (primary, secondary CEs)
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is configured on the FE and the CE during pre-association by the FEM
and the CEM respectively.
This section includes a new normative description that updates
[RFC5810] for the Cold-Standby High Availability mechanism.
Figure 2 below illustrates the Forces message sequences that the FE
uses to recover the connection in current defined cold-standby
scheme.
FE CE Primary CE Secondary
| | |
| Association Establishment | |
| Capabilities Exchange | |
1 |<------------------------->| |
| | |
| State Update | |
2 |<------------------------->| |
| | |
| | |
| FAILURE |
| |
| Association Estbalishment,Capabilities Exchange |
3 |<----------------------------------------------->|
| |
| Event Report (primary CE down) |
4 |------------------------------------------------>|
| |
| State Update |
5 |<----------------------------------------------->|
Figure 2: CE Failover for Cold Standby
3.1.1. Cold Standby Interaction with ForCES Protocol
HA parameterization in an FE is driven by configuring the FE Protocol
Object (FEPO) LFB.
The FEPO CEID component identifies the current master CE and the
component table BackupCEs identifies the configured backup CEs. The
FEPO FE Heartbeat Interval, CE Heartbeat Dead Interval, and CE
Heartbeat policy help in detecting connectivity problems between an
FE and CE. The CE Failover policy defines how the FE should react on
a detected failure. The FEObject FEState component [RFC5812] defines
the operational forwarding status and control. The CE can turn off
the FE's forwarding operations by setting the FEState to AdminDisable
and can turn it on by setting it to OperEnable. Note: [RFC5812]
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section 5.1 has an errata which describes the FEState as read-only
when it should be read-write.
Figure 3 illustrates the defined state machine that facilitates the
recovery of connection state.
The FE connects to the CE specified on FEPO CEID component. If it
fails to connect to the defined CE, it moves it to the bottom of
table BackupCEs and sets its CEID component to be the first CE
retrieved from table BackupCEs. The FE then attempts to associate
with the CE designated as the new primary CE. The FE continues
through this procedure until it successfully connects to one of the
CEs or until the CE Failover Timeout Interval (CEFTI) expires.
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FE tries to associate
+-->-----+
| |
(CE changes master || | |
CE issues Teardown || +---+--------v----+
Lost association) && | Pre-Association |
CE failover policy = 0 | (Association |
+------------>-->-->| in +<----+
| | progress) | |
| | | |
| +--------+--------+ |
| CE Association | | CEFTI
| Response V | timer
| +------------------+ | expires
| |FE issue CEPrimaryDown ^
| V |
+-+-----------+ +------+-----+
| | (CE changes master || | Not |
| | CE issues Teardown || | Associated |
| | Lost association) && | +->---+
| Associated | CE Failover Policy = 1 |(May | FE |
| | | Continue | try v
| |-------->------->------>| Forwarding)| assn|
| | Start CEFTI timer | |-<---+
| | | |
+-------------+ +-------+-----+
^ |
| Successful V
| Association |
| Setup |
| (Cancel CEFTI Timer) |
+_________________________________________+
FE issue CEPrimaryDown event
Figure 3: FE State Machine considering HA
There are several events that trigger mastership changes: The master
CE may issue a mastership change (by changing the CEID component), or
teardown an existing association; and last, connectivity may be lost
between the CE and FE.
When communication fails between the FE and CE (which can be caused
by either the CE or link failure but not FE related), either the TML
on the FE will trigger the FE PL regarding this failure or it will be
detected using the heartbeat messages between FEs and CEs. The
communication failure, regardless of how it is detected, MUST be
considered as a loss of association between the CE and corresponding
FE.
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If the FE's FEPO CE Failover Policy is configured to mode 0 (the
default), it will immediately transition to the pre-association
phase. This means that if association is later re-established with a
CE, all FE state will need to be re-created.
If the FE's FEPO CE Failover Policy is configured to mode 1, it
indicates that the FE will run in HA restart recovery. In such a
case, the FE transitions to the Not Associated state and the CEFTI
timer [RFC5810] is started. The FE may continue to forward packets
during this state depending upon the value of the CEFailoverPolicy
component of the FEPO LFB. The FE recycles through any configured
backup CEs in a round-robin fashion. It first adds its primary CE to
the bottom of table BackupCEs and sets its CEID component to be the
first secondary retrieved from table BackupCEs. The FE then attempts
to associate with the CE designated as the new primary CE. If it
fails to re-associate with any CE and the CEFTI expires, the FE then
transitions to the pre-association state and FE will operationally
bring down its forwarding path (and set the [RFC5812] FEObject
FEState component to OperDisable).
If the FE, while in the not associated state, manages to reconnect to
a new primary CE before CEFTI expires it transitions to the
Associated state. Once re-associated, the CE may try to synchronize
any state that the FE may have lost during disconnection. How the CE
re-synchronizes such state is out of scope for the current ForCES
architecture but would typically constitute the issuing of new
configs and queries.
An explicit message (a Config message setting Primary CE component in
ForCES Protocol object) from the primary CE, can also be used to
change the Primary CE for an FE during normal protocol operation. In
this case, the FE transitions to the Not Associated State and
attempts to Associate with the new CE.
3.1.2. Responsibilities for HA
TML Level:
1. The TML controls logical connection availability and failover.
2. The TML also controls peer HA management.
At this level, control of all lower layers, for example transport
level (such as IP addresses, MAC addresses etc) and associated links
going down are the role of the TML.
PL Level:
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All other functionality, including configuring the HA behavior during
setup, the Control Element IDs (CE IDs) used to identify primary and
secondary CEs, protocol messages used to report CE failure (Event
Report), Heartbeat messages used to detect association failure,
messages to change the primary CE (Config), and other HA related
operations described in Section 3.1, are the PL's responsibility.
To put the two together, if a path to a primary CE is down, the TML
would help recover from a failure by switching over to a backup path,
if one is available. If the CE is totally unreachable then the PL
would be informed and it would take the appropriate actions described
before.
4. CE HA Hot Standby
In this section we describe small extensions to the existing scheme
to enable hot standby HA. To achieve hot standby HA, we target to
improve the specific goals defined in Section 2.2, namely:
o How fast a backup CE becomes operational.
o How fast the FEs associate with the new master CE.
As described in Section 3.1, in the pre-association phase the FEM
configures the FE to make it aware of all the CEs in the NE. The FEM
MUST configure the FE to make it aware which CE is the master and MAY
specify any backup CE(s).
4.1. Changes to the FEPO model
In order for the above to be achievable there is a need to make a few
changes in the FEPO model. Appendix A contains the xml definition of
the new version 1.1 of the FEPO LFB.
Changes from the version 1 of FEPO are:
1. Added four new datatypes:
1. CEStatusType an unsigned char to specify status of a
connection with a CE. Special values are:
+ 0 (Disconnected) represents that no connection attempt has
been made with the CE yet
+ 1 (Connected) represents that the FE connection with the
CE at the TML has completed successfully
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+ 2 (Associated) represents that the FE has successfully
associated with the CE
+ 3 (IsMaster) represents that the FE has associated with
the CE and is the master of the FE
+ 4 (LostConnection) represents that the FE was associated
with the CE at one point but lost the connection
+ 5 (Unreachable) represents the FE deems this CE
unreachable. i.e., the FE has tried over a period to
connect to it but has failed.
2. HAModeValues an unsigned char to specify selected HA mode.
Special values are:
+ 0 (No HA Mode) represents that the FE is not running in HA
mode
+ 1 (HA Mode - Cold Standby) represents that the FE is in HA
mode cold Standby
+ 2 (HA Mode - Hot Standby) represents that the FE is in HA
mode hot Standby
3. Statistics, a complex structure, representing the
communication statistics between the FE and CE. The
components are:
+ RecvPackets representing the packet count received from
the CE
+ RecvBytes representing the byte count received from the CE
+ RecvErrPackets representing the erroneous packets received
from the CE. This component logs badly formatted packets
as well as good packets sent to the FE by the CE to set
components whilst that CE is not the master. Erroneous
packets are dropped(i.e. not responded to).
+ RecvErrBytes representing the RecvErrPackets byte count
received from the CE
+ TxmitPackets representing the packet count transmitted to
the CE
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+ TxmitErrPackets representing the error packet count
transmitted to the CE. Typically these would be failures
due to communication.
+ TxmitBytes representing the byte count transmitted to the
CE
+ TxmitErrBytes representing the byte count of errors from
transmit to the CE
4. AllCEType, a complex structure constituting the CE IDs,
Statistics and CEStatusType to reflect connection information
for one CE. Used in the AllCEs component array.
2. Appended two new components:
1. Read-only AllCEs to hold status for all CEs. AllCEs is an
Array of the AllCEType.
2. Read-write HAMode of type HAModeValues to carry the HA mode
used by the FE.
3. Added one additional Event, PrimaryCEChanged, reporting the new
master CE ID when there is a mastership change.
Since no component from the FEPO v1 has been changed FEPO v1.1
retains backwards compatibility with CEs that know only version 1.0.
These CEs however cannot make use of the HA options that the new FEPO
provides.
4.2. FEPO processing
The FE's FEPO LFB version 1.1 AllCEs table contains all the CE IDs
that the FE may connect and associate with. The ordering of the CE
IDs in this table defines the priority order in which an FE will
connect to the CEs. This table is provisioned initially from the
configuration plane (FEM). In the pre-association phase, the first
CE (lowest table index) in the AllCEs table MUST be the first CE that
the FE will attempt to connect and associate with. If the FE fails
to connect and associate with the first listed CE, it will attempt to
connect to the second CE and so forth, and cycles back to the
beginning of the list until there is a successful association. The
FE MUST associate with at least one CE. Upon a successful
association, a component of the FEPO LFB, specifically the CEID
component, identifies the current associated master CE.
While it would be much simpler to have the FE not respond to any
messages from a CE other than the master, in practice it has been
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found to be useful to respond to queries and heartbeats from backup
CEs. For this reason, we allow backup CEs to issues queries to the
FE. Configuration messages (SET/DEL) from backup CEs MUST be dropped
by the FE and logged as received errors.
Asynchronous events that the master CE has subscribed to, as well as
heartbeats are sent to all associated-to CEs. Packet redirects
continue to be sent only to the master CE. The Heartbeat Interval,
the CE Heartbeat Policy (CEHB) and the FE Heartbeat Policy (FEHB) are
global for all CEs(and changed only by the master CE).
Figure 4 illustrates the state machine that facilitates connection
recovery with HA enabled.
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FE tries to associate
+-->-----+
| |
(CE changes master || | |
CE issues Teardown || +---+--------v----+
Lost association) && | Pre-Association |
CE failover policy = 0 | (Association |
+------------>-->-->| in +<----+
| | progress) | |
| | | |
| +--------+--------+ |
| CE Association | | CEFTI
| Response V | timer
| +------------------+ | expires
| |FE issue CEPrimaryDown ^
| |FE issue PrimaryCEChanged ^
| V |
+-+-----------+ +------+-----+
| | (CE changes master || | Not |
| | CE issues Teardown || | Associated |
| | Lost association) && | +->----------+
| Associated | CE Failover Policy = 1 |(May | find first |
| | | Continue | associated v
| |-------->------->------>| Forwarding)| CE or retry|
| | Start CEFTI timer | | associating|
| | | |-<----------+
| | | |
+----+--------+ +-------+----+
| |
^ Found | associated CE
| or newly | associated CE
| V
| (Cancel CEFTI Timer) |
+_________________________________________+
FE issue CEPrimaryDown event
FE issue PrimaryCEChanged event
Figure 4: FE State Machine considering HA
Once the FE has associated with a master CE it moves to the post-
association phase (Associated state). It is assumed that the master
CE will communicate with other CEs within the NE for the purpose of
synchronization via the CE-CE interface. The CE-CE interface is out
of scope for this document. An election result amongst CEs may
result in desire to change mastership to a different associated CE;
at which point current assumed master CE will instruct the FE to use
a different master CE.
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FE CE#1 CE#2 ... CE#N
| | | |
| Association Establishment | | |
| Capabilities Exchange | | |
1 |<------------------------->| | |
| | | |
| State Update | | |
2 |<------------------------->| | |
| | | |
| Association Establishment | |
| Capabilities Exchange | |
3I|<-------------------------------------->| |
... ... ... ...
| Association Estbalishment,Capabilities Exchange |
3N|<----------------------------------------------->|
| | | |
4 |<------------------------->| | |
. . . .
4x|<------------------------->| | |
| FAILURE | |
| | | |
| Event Report (LastCEID changed) | |
5 |--------------------------------------->|------->|
| Event Report (CE#2 is new master) | |
6 |--------------------------------------->|------->|
| | |
7 |<-------------------------------------->| |
. . . .
7x|<-------------------------------------->| |
. . . .
Figure 5: CE Failover for Hot Standby
While in the post-association phase, if the CE Failover Policy is set
to 1 and HAMode set to 2 (HotStandby) then the FE, after successfully
associating with the master CE, MUST attempt to connect and associate
with all the CEs that it is aware of. Figure 5 steps #1 and #2
illustrates the FE associating with CE#1 as the master and then
proceeding to steps #3I to #3N the association with backup CEs CE#2
to CE#N. If the FE fails to connect or associate with some CEs, the
FE MAY flag them as unreachable to avoid continuous attempts to
connect. The FE MAY retry to reassociate with unreachable CEs when
possible.
When the master CE for any reason is considered to be down, then the
FE MUST try to find the first associated CE from the list of all CEs
in a round-robin fashion.
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If the FE is unable to find an associated FE in its list of CEs, then
it MUST attempt to connect and associate with the first from the list
of all CEs and continue in a round-robin fashion until it connects
and associates with a CE or the CEFTI timer expires.
Once the FE selects an associated CE to use as the new master, the FE
issues a PrimaryCEDown Event Notification to all associated CEs to
notify them that the last primary CE went down (and what its identity
was); a second event PrimaryCEChanged identifying the new master CE
is sent as well to identify which CE the reporting FE considers to be
the new master.
In most HA architectures there exists the possibility of split-brain.
However, since in our setup the FE will never accept any
configuration messages from any other than the master CE, we consider
the FE as fenced against data corruption from the other CEs that
consider themselves as the master. The split-brain issue becomes
mostly a CE-CE communication problem which is considered to be out of
scope.
By virtue of having multiple CE connections, the FE switchover to a
new master CE will be relatively much faster. The overall effect is
improving the NE recovery time in case of communication failure or
faults of the master CE. This satisfies the requirement we set to
achieve.
5. IANA Considerations
Following the policies outlined in "Guidelines for Writing an IANA
Considerations Section in RFCs" [RFC5226], the Logical Functional
Block (LFB) Class Names and Class Identifiers namespaces is updated.
A new column, LFB version, is added to the table after the LFB Class
Name. The table now reads as follows:
+----------------+------------+-----------+-------------+-----------+
| LFB Class | LFB Class | LFB | Description | Reference |
| Identifier | Name | Version | | |
+----------------+------------+-----------+-------------+-----------+
+----------------+------------+-----------+-------------+-----------+
Logical Functional Block (LFB) Class Names and Class Identifiers
The same rules applies as defined in [RFC5812] with the addition that
entries must provide the LFB version as a string.
Upon publication of this document, all current entries are assigned a
value of 1.0.
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New versions of already defined LFB, MUST NOT remove the previous
version entries.
It would make sense to have LFB versions to appear in sequence in the
registry. The table SHOULD be sorted, and the shorting should be
done by Class ID first and then by version.
This document introduces the FE Protocol Object version 1.1 as
follows:
+------------+-----------+---------+--------------------+-----------+
| LFB Class | LFB Class | LFB | Description | Reference |
| Identifier | Name | Version | | |
+------------+-----------+---------+--------------------+-----------+
| 2 | FE | 1.1 | Defines parameters | This |
| | Protocol | | for the ForCES | document |
| | Object | | protocol operation | |
+------------+-----------+---------+--------------------+-----------+
Logical Functional Block (LFB) Class Names and Class Identifiers
6. Security Considerations
Security consideration as defined in section 9 of [RFC5810] applies
securing each CE-FE communication. Multiple CEs associated with the
same FE still require the same procedure to be followed on a per-
association basis.
It should be noted that since the FE is initiating the association
with a CE, a CE cannot initiate association with the FE and such
messages will be dropped. Thus the FE is secured from rogue CEs that
are attempting to associate with it.
CE implementers should have in mind that once associated the FE
cannot distinguish whether the CE has been compromised or
malfunctioning while not losing connectivity. Securing the CE is out
of scope of this document.
While CE-CE plane is outside current scope of ForCES, we recognize
that it may be subjected to attacks which may affect the CE-FE
communication.
The following considerations should be made:
1. CEs should use secure communication channels between for
coordination and keeping of state at least to avoid connection of
malicious CEs.
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2. The master CE should take into account DoS and DDoS attacks from
malicious or malfunctioning CEs.
3. CEs should take into account the split-brain issue. There are
currently two fail-safes in the FE, firstly the FE has the CEID
component that denotes which CE is the master and secondly the FE
does not allow BackupCEs to configure the FE. However backup CEs
that consider that the master CE has dropped and themselves as
master should first do a sanity check and query the FE CEID
component.
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5810] Doria, A., Hadi Salim, J., Haas, R., Khosravi, H., Wang,
W., Dong, L., Gopal, R., and J. Halpern, "Forwarding and
Control Element Separation (ForCES) Protocol
Specification", RFC 5810, March 2010.
[RFC5812] Halpern, J. and J. Hadi Salim, "Forwarding and Control
Element Separation (ForCES) Forwarding Element Model", RFC
5812, March 2010.
7.2. Informative References
[RFC3654] Khosravi, H. and T. Anderson, "Requirements for Separation
of IP Control and Forwarding", RFC 3654, November 2003.
[RFC3746] Yang, L., Dantu, R., Anderson, T., and R. Gopal,
"Forwarding and Control Element Separation (ForCES)
Framework", RFC 3746, April 2004.
Appendix A. New FEPO version
The xml has been validated against the schema defined in [RFC5812].
<LFBLibrary xmlns="urn:ietf:params:xml:ns:forces:lfbmodel:1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="lfb-schema.xsd" provides="FEPO">
<!-- XXX -->
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<dataTypeDefs>
<dataTypeDef>
<name>CEHBPolicyValues</name>
<synopsis>
The possible values of CE heartbeat policy
</synopsis>
<atomic>
<baseType>uchar</baseType>
<specialValues>
<specialValue value="0">
<name>CEHBPolicy0</name>
<synopsis>
The CE will send heartbeats to the FE
every CEHDI timeout if no other messages
have been sent since.
</synopsis>
</specialValue>
<specialValue value="1">
<name>CEHBPolicy1</name>
<synopsis>
The CE will not send heartbeats to the FE
</synopsis>
</specialValue>
</specialValues>
</atomic>
</dataTypeDef>
<dataTypeDef>
<name>FEHBPolicyValues</name>
<synopsis>
The possible values of FE heartbeat policy
</synopsis>
<atomic>
<baseType>uchar</baseType>
<specialValues>
<specialValue value="0">
<name>FEHBPolicy0</name>
<synopsis>
The FE will not generate any heartbeats to the CE
</synopsis>
</specialValue>
<specialValue value="1">
<name>FEHBPolicy1</name>
<synopsis>
The FE generates heartbeats to the CE every FEHI
if no other messages have been sent to the CE.
</synopsis>
</specialValue>
</specialValues>
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</atomic>
</dataTypeDef>
<dataTypeDef>
<name>FERestartPolicyValues</name>
<synopsis>
The possible values of FE restart policy
</synopsis>
<atomic>
<baseType>uchar</baseType>
<specialValues>
<specialValue value="0">
<name>FERestartPolicy0</name>
<synopsis>
The FE restarts its state from scratch
</synopsis>
</specialValue>
</specialValues>
</atomic>
</dataTypeDef>
<dataTypeDef>
<name>HAModeValues</name>
<synopsis>
The possible values of HA modes
</synopsis>
<atomic>
<baseType>uchar</baseType>
<specialValues>
<specialValue value="0">
<name>NoHA</name>
<synopsis>
The FE is not running in HA mode
</synopsis>
</specialValue>
<specialValue value="1">
<name>ColdStandby</name>
<synopsis>
The FE is running in HA mode cold Standby
</synopsis>
</specialValue>
<specialValue value="2">
<name>HotStandby</name>
<synopsis>
The FE is running in HA mode hot Standby
</synopsis>
</specialValue>
</specialValues>
</atomic>
</dataTypeDef>
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<dataTypeDef>
<name>CEFailoverPolicyValues</name>
<synopsis>
The possible values of CE failover policy
</synopsis>
<atomic>
<baseType>uchar</baseType>
<specialValues>
<specialValue value="0">
<name>CEFailoverPolicy0</name>
<synopsis>
The FE should stop functioning immediate and
transition to the FE OperDisable state
</synopsis>
</specialValue>
<specialValue value="1">
<name>CEFailoverPolicy1</name>
<synopsis>
The FE should continue forwarding even without an
associated CE for CEFTI. The FE goes to FE
OperDisable when the CEFTI expires and no
association. Requires graceful restart support.
</synopsis>
</specialValue>
</specialValues>
</atomic>
</dataTypeDef>
<dataTypeDef>
<name>FEHACapab</name>
<synopsis>
The supported HA features
</synopsis>
<atomic>
<baseType>uchar</baseType>
<specialValues>
<specialValue value="0">
<name>GracefullRestart</name>
<synopsis>
The FE supports Graceful Restart
</synopsis>
</specialValue>
<specialValue value="1">
<name>HA</name>
<synopsis>
The FE supports HA
</synopsis>
</specialValue>
</specialValues>
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</atomic>
</dataTypeDef>
<dataTypeDef>
<name>CEStatusType</name>
<synopsis>Status values. Status for each CE</synopsis>
<atomic>
<baseType>uchar</baseType>
<specialValues>
<specialValue value="0">
<name>Disconnected</name>
<synopsis>No connection attempt with the CE yet
</synopsis>
</specialValue>
<specialValue value="1">
<name>Connected</name>
<synopsis>The FE connection with the CE at the TML
has been completed
</synopsis>
</specialValue>
<specialValue value="2">
<name>Associated</name>
<synopsis>The FE has associated with the CE
</synopsis>
</specialValue>
<specialValue value="3">
<name>IsMaster</name>
<synopsis>The CE is the master (and associated)
</synopsis>
</specialValue>
<specialValue value="4">
<name>LostConnection</name>
<synopsis>The FE was associated with the CE but
lost the connection
</synopsis>
</specialValue>
<specialValue value="5">
<name>Unreachable</name>
<synopsis>The CE is deemed as unreachable by the FE
</synopsis>
</specialValue>
</specialValues>
</atomic>
</dataTypeDef>
<dataTypeDef>
<name>StatisticsType</name>
<synopsis>Statistics Definition</synopsis>
<struct>
<component componentID="1">
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<name>RecvPackets</name>
<synopsis>Packets Received</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="2">
<name>RecvErrPackets</name>
<synopsis>Packets Received from CE with errors
</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="3">
<name>RecvBytes</name>
<synopsis>Bytes Received from CE</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="4">
<name>RecvErrBytes</name>
<synopsis>Bytes Received from CE in Error</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="5">
<name>TxmitPackets</name>
<synopsis>Packets Transmitted to CE</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="6">
<name>TxmitErrPackets</name>
<synopsis>
Packets Transmitted to CE that incurred
errors
</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="7">
<name>TxmitBytes</name>
<synopsis>Bytes Transmitted to CE</synopsis>
<typeRef>uint64</typeRef>
</component>
<component componentID="8">
<name>TxmitErrBytes</name>
<synopsis>Bytes Transmitted to CE incurring errors
</synopsis>
<typeRef>uint64</typeRef>
</component>
</struct>
</dataTypeDef>
<dataTypeDef>
<name>AllCEType</name>
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<synopsis>Table Type for AllCE component</synopsis>
<struct>
<component componentID="1">
<name>CEID</name>
<synopsis>ID of the CE</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="2">
<name>Statistics</name>
<synopsis>Statistics per CE</synopsis>
<typeRef>StatisticsType</typeRef>
</component>
<component componentID="3">
<name>CEStatus</name>
<synopsis>Status of the CE</synopsis>
<typeRef>CEStatusType</typeRef>
</component>
</struct>
</dataTypeDef>
</dataTypeDefs>
<LFBClassDefs>
<LFBClassDef LFBClassID="2">
<name>FEPO</name>
<synopsis>
The FE Protocol Object, with new CEHA
</synopsis>
<version>1.1</version>
<components>
<component componentID="1" access="read-only">
<name>CurrentRunningVersion</name>
<synopsis>Currently running ForCES version</synopsis>
<typeRef>uchar</typeRef>
</component>
<component componentID="2" access="read-only">
<name>FEID</name>
<synopsis>Unicast FEID</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="3" access="read-write">
<name>MulticastFEIDs</name>
<synopsis>
the table of all multicast IDs
</synopsis>
<array type="variable-size">
<typeRef>uint32</typeRef>
</array>
</component>
<component componentID="4" access="read-write">
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<name>CEHBPolicy</name>
<synopsis>
The CE Heartbeat Policy
</synopsis>
<typeRef>CEHBPolicyValues</typeRef>
</component>
<component componentID="5" access="read-write">
<name>CEHDI</name>
<synopsis>
The CE Heartbeat Dead Interval in millisecs
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="6" access="read-write">
<name>FEHBPolicy</name>
<synopsis>
The FE Heartbeat Policy
</synopsis>
<typeRef>FEHBPolicyValues</typeRef>
</component>
<component componentID="7" access="read-write">
<name>FEHI</name>
<synopsis>
The FE Heartbeat Interval in millisecs
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="8" access="read-write">
<name>CEID</name>
<synopsis>
The Primary CE this FE is associated with
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="9" access="read-write">
<name>BackupCEs</name>
<synopsis>
The table of all backup CEs other than the
primary
</synopsis>
<array type="variable-size">
<typeRef>uint32</typeRef>
</array>
</component>
<component componentID="10" access="read-write">
<name>CEFailoverPolicy</name>
<synopsis>
The CE Failover Policy
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</synopsis>
<typeRef>CEFailoverPolicyValues</typeRef>
</component>
<component componentID="11" access="read-write">
<name>CEFTI</name>
<synopsis>
The CE Failover Timeout Interval in millisecs
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="12" access="read-write">
<name>FERestartPolicy</name>
<synopsis>
The FE Restart Policy
</synopsis>
<typeRef>FERestartPolicyValues</typeRef>
</component>
<component componentID="13" access="read-write">
<name>LastCEID</name>
<synopsis>
The Primary CE this FE was last associated
with
</synopsis>
<typeRef>uint32</typeRef>
</component>
<component componentID="14" access="read-write">
<name>HAMode</name>
<synopsis>
The HA mode used
</synopsis>
<typeRef>HAModeValues</typeRef>
</component>
<component componentID="15" access="read-only">
<name>AllCEs</name>
<synopsis>The table of all CEs</synopsis>
<array type="variable-size">
<typeRef>AllCEType</typeRef>
</array>
</component>
</components>
<capabilities>
<capability componentID="30">
<name>SupportableVersions</name>
<synopsis>
the table of ForCES versions that FE supports
</synopsis>
<array type="variable-size">
<typeRef>uchar</typeRef>
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</array>
</capability>
<capability componentID="31">
<name>HACapabilities</name>
<synopsis>
the table of HA capabilities the FE supports
</synopsis>
<array type="variable-size">
<typeRef>FEHACapab</typeRef>
</array>
</capability>
</capabilities>
<events baseID="61">
<event eventID="1">
<name>PrimaryCEDown</name>
<synopsis>
The primary CE has changed
</synopsis>
<eventTarget>
<eventField>LastCEID</eventField>
</eventTarget>
<eventChanged/>
<eventReports>
<eventReport>
<eventField>LastCEID</eventField>
</eventReport>
</eventReports>
</event>
<event eventID="2">
<name>PrimaryCEChanged</name>
<synopsis>A New primary CE has been selected
</synopsis>
<eventTarget>
<eventField>CEID</eventField>
</eventTarget>
<eventChanged/>
<eventReports>
<eventReport>
<eventField>CEID</eventField>
</eventReport>
</eventReports>
</event>
</events>
</LFBClassDef>
</LFBClassDefs>
</LFBLibrary>
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Authors' Addresses
Kentaro Ogawa
NTT Corporation
3-9-11 Midori-cho
Musashino-shi, Tokyo 180-8585
Japan
Email: k.ogawa@ntt.com
Weiming Wang
Zhejiang Gongshang University
149 Jiaogong Road
Hangzhou 310035
P.R.China
Phone: +86-571-88057712
Email: wmwang@mail.zjgsu.edu.cn
Evangelos Haleplidis
University of Patras
Panepistimioupoli Patron
Patras 26504
Greece
Email: ehalep@ece.upatras.gr
Jamal Hadi Salim
Mojatatu Networks
Suite 400, 303 Moodie Dr.
Ottawa, Ontario K2H 9R4
Canada
Email: hadi@mojatatu.com
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