draft-ietf-ccamp-rsvp-restart-ext-02.txt   draft-ietf-ccamp-rsvp-restart-ext-03.txt 
Network Working Group A. Satyanarayana (Cisco Systems) Network Working Group A. Satyanarayana, Ed.
Internet Draft R. Rahman (Cisco Systems) Internet-Draft R. Rahman, Ed.
Expiration Date: September 2005 Editors Updates: 2961, 3473 (if approved) Cisco Systems
Expires: December 3, 2005 L. Berger
March 2005 Movaz Networks
D. Papadimitriou
Alcatel
A. Zamfir
J. Israr
Cisco Systems
June 2005
Extensions to GMPLS RSVP Graceful Restart Extensions to GMPLS RSVP Graceful Restart
draft-ietf-ccamp-rsvp-restart-ext-03
draft-ietf-ccamp-rsvp-restart-ext-02.txt
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Copyright (C) The Internet Society (2005).
Abstract Abstract
This document describes extensions to the RSVP Graceful Restart This document describes extensions to the RSVP Graceful Restart
mechanisms defined in RFC 3473. The extensions enable the recovery mechanisms defined in RFC 3473. The extensions enable the recovery
of RSVP signaling state based on the Path message last sent by the of RSVP signaling state based on the Path message last sent by the
node being restarted. Previously defined Graceful Restart node being restarted. Previously defined Graceful Restart
mechanisms, also called recovery from nodal faults, permit recovery mechanisms, also called recovery from nodal faults, permit recovery
of signaling state from adjacent nodes when the data plane has of signaling state from adjacent nodes when the data plane has
retained the associated forwarding state across a restart. These retained the associated forwarding state across a restart. These
mechanisms do not fully support signaling state recovery on ingress mechanisms do not fully support signaling state recovery on ingress
nodes or recovery of all RSVP objects. The presented extensions use nodes or recovery of all RSVP objects. The presented extensions use
the RSVP Hello extensions defined in RFC 3209, and extensions for the RSVP Hello extensions defined in RFC 3209, and extensions for
state recovery on nodal faults defined in RFC 3473. With the state recovery on nodal faults defined in RFC 3473. With the
presented extensions the restarting node can recover all previously presented extensions the restarting node can recover all previously
transmitted Path state including the ERO and the downstream transmitted Path state including the Explicit Route Object and the
(outgoing) interface identifiers. The extensions can also be used to downstream (outgoing) interface identifiers. The extensions can also
recover signaling state after the restart of an ingress node. The be used to recover signaling state after the restart of an ingress
extensions optionally support the use of Summary Refresh, defined in node. The extensions optionally support the use of Summary Refresh,
RFC 2961, to reduce the number of messages exchanged during the defined in RFC 2961, to reduce the number of messages exchanged
Recovery Phase when the restarting node has recovered signaling state during the Recovery Phase when the restarting node has recovered
locally for one or more LSP's. signaling state locally for one or more LSPs.
Contents Table of Contents
1 Introduction .............................................. 3 1. Conventions used in this document . . . . . . . . . . . . 4
2 Extensions to Nodal Fault Handling ........................ 5 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 RecoveryPath Message Format ............................... 5 3. Introduction . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Related Procedures ........................................ 5 4. Extensions to Nodal Fault Handling . . . . . . . . . . . . 6
2.3 Procedures For The Downstream Neighbor .................... 6 4.1 RecoveryPath Message Format . . . . . . . . . . . . . . . 6
2.4 Procedures for the Restarting Node ........................ 7 4.2 Capability Object . . . . . . . . . . . . . . . . . . . . 6
2.4.1 Path and RecoveryPath Message Procedures .................. 7 4.2.1 Conformance . . . . . . . . . . . . . . . . . . . . . . . 7
2.4.2 Re-Synchronization Procedures ............................. 8 4.3 Related Procedures . . . . . . . . . . . . . . . . . . . . 8
2.4.3 Procedures on Expiration of Recovery Period ............... 9 4.4 Procedures for the Capability Object . . . . . . . . . . . 8
2.5 Compatibility ............................................. 9 4.4.1 Procedures for the Downstream Neighbor . . . . . . . . . . 8
3 RecoveryPath Summary Refresh .............................. 10 4.4.2 Procedures for the Restarting Node . . . . . . . . . . . . 9
3.1 MESSAGE_ID ACK/NACK and MESSAGE_ID LIST Objects ........... 11 4.5 Procedures for the RecoveryPath message . . . . . . . . . 9
3.2 Capability Object ......................................... 12 4.5.1 Procedures For The Downstream Neighbor . . . . . . . . . . 9
3.2.1 Procedures ................................................ 13 4.5.2 Procedures for the Restarting Node . . . . . . . . . . . . 11
3.2.2 Compatibility ............................................. 13 4.5.2.1 Path and RecoveryPath Message Procedures . . . . . . . . . 11
3.3 RecoveryPath Summary Refresh Procedures ................... 14 4.5.2.2 Re-Synchronization Procedures . . . . . . . . . . . . . . 12
3.3.1 Generation of RecoveryPath-related Srefresh Messages ...... 14 4.5.2.3 Procedures on Expiration of Recovery Period . . . . . . . 13
3.3.2 RecoveryPath-related Srefresh Receive Processing and NACK 4.6 Compatibility . . . . . . . . . . . . . . . . . . . . . . 13
Generation ................................................ 15 5. RecoveryPath Summary Refresh . . . . . . . . . . . . . . . 14
3.3.3 RecoveryPath-related MESSAGE_ID NACK Receive Processing ... 16 5.1 MESSAGE_ID ACK/NACK and MESSAGE_ID LIST Objects . . . . . 15
4 Acknowledgments ........................................... 17 5.2 RecoveryPath Srefresh Capable bit . . . . . . . . . . . . 16
5 Security Considerations ................................... 17 5.2.1 Procedures . . . . . . . . . . . . . . . . . . . . . . . . 16
6 IANA Considerations ....................................... 17 5.2.2 Compatibility . . . . . . . . . . . . . . . . . . . . . . 17
7 References ................................................ 17 5.3 RecoveryPath Summary Refresh Procedures . . . . . . . . . 17
7.1 Normative References ...................................... 17 5.3.1 Generation of RecoveryPath-related Srefresh Messages . . . 17
7.2 Informative References .................................... 18 5.3.2 RecoveryPath-related Srefresh Receive Processing and
8 Authors' Addresses ........................................ 18 NACK Generation . . . . . . . . . . . . . . . . . . . . . 19
9 Intellectual Property Considerations ...................... 19 5.3.3 RecoveryPath-related MESSAGE_ID NACK Receive Processing . 19
10 Disclaimer of Validity .................................... 20 6. Security Considerations . . . . . . . . . . . . . . . . . 20
11 Full Copyright Statement .................................. 20 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . 20
8. IANA Considerations . . . . . . . . . . . . . . . . . . . 21
9. Normative References . . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . 22
Intellectual Property and Copyright Statements . . . . . . 24
Conventions used in this document 1. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in [RFC2119].
1. Introduction 2. Terminology
The reader is assumed to be familiar with the terminology defined in
xref target="RFC3209" /> and [RFC3473].
Throughout this document, the term "node" when used in the context of
a restarting or restarted node generally refers to the control plane
component which is the signaling controller for a data plane switch.
3. Introduction
RSVP Graceful Restart is defined in [RFC3473] and uses mechanisms RSVP Graceful Restart is defined in [RFC3473] and uses mechanisms
defined in [RFC3209]. [RFC3209] describes a mechanism, using RSVP defined in [RFC3209]. When data/forwarding plane state can be
Hello messages, to detect the state of an adjacent RSVP agent. retained across the restart of the RSVP agent that established such
state, RSVP Graceful Restart provides the ability for the RSVP agent
to resynchronize its state based on updates received from its
neighboring RSVP agents, and, reconcile such state with the retained
data/forwarding plane state. [RFC3209] describes a mechanism, using
RSVP Hello messages, to detect the state of an adjacent RSVP agent.
[RFC3473] extends this mechanism to advertise the capability of [RFC3473] extends this mechanism to advertise the capability of
retaining data / forwarding plane state across the restart of a node retaining data/forwarding plane state across the restart of a node or
or a "nodal fault". [RFC3473] also defines the Recovery Label object a "nodal fault". [RFC3473] also defines the Recovery Label object
for use in the Path message of the RSVP neighbor upstream of a for use in the Path message of the RSVP neighbor upstream of a
restarting node, to indicate that the Path message is for existing restarting node, to indicate that the Path message is for existing
data plane state. data plane state.
This document presents extensions to address two aspects of graceful This document presents extensions to address two aspects of graceful
restart not previously supported. The presented extensions enable a restart not previously supported. The presented extensions enable a
restarting node to recover all objects in previously transmitted Path restarting node to recover all objects in previously transmitted Path
messages including the ERO, from its downstream neighbors. The messages including the Explicit Route Object (ERO), from its
extensions also enable graceful restart of an ingress node that does downstream neighbors. The extensions also enable graceful restart of
not preserve full RSVP state across restarts. an ingress node that does not preserve full RSVP state across
restarts. The presented extensions are equally applicable to LSPs of
various switching types as defined in [RFC3471].
Per [RFC3473], a restarting node can distinguish Path messages Per [RFC3473], a restarting node can distinguish Path messages
associated with LSPs being recovered by the presence of the Recovery associated with LSPs being recovered by the presence of the Recovery
Label object. To determine the downstream (outgoing) interface and Label object. To determine the downstream (outgoing) interface and
associated label(s), the restarting node must consult the data plane. associated label(s), the restarting node must consult the data plane.
This may not be possible for all types of nodes. Furthermore, data This may not be possible for all types of nodes. Furthermore, data
plane information is not sufficient to reconstruct all previously plane information is not sufficient to reconstruct all previously
transmitted Path state. In these cases, the only source of RSVP transmitted Path state. In these cases, the only source of RSVP
state is the downstream RSVP neighbor. state is the downstream RSVP neighbor.
skipping to change at page 4, line 14 skipping to change at page 5, line 29
been based on configuration or the result of a previous path been based on configuration or the result of a previous path
computation. A restarting transit node may have previously performed computation. A restarting transit node may have previously performed
some form of path computation as a result of not receiving an ERO or some form of path computation as a result of not receiving an ERO or
receiving a loose hop in the ERO. In addition to the ERO, the receiving a loose hop in the ERO. In addition to the ERO, the
restarting node may have modified other received Path state in its restarting node may have modified other received Path state in its
previously transmitted Path state, which cannot be reconstructed previously transmitted Path state, which cannot be reconstructed
internally during recovery. internally during recovery.
The defined extensions provide a restarting upstream node with all The defined extensions provide a restarting upstream node with all
information previously transmitted by the node in Path messages. information previously transmitted by the node in Path messages.
This is accomplished by the downstream RSVP neighbor, after This is accomplished by the downstream RSVP neighbor sending a new
reestablishing RSVP communication with the restarted node, sending a message for every Path message it has previously received from the
new message for every Path message it has previously received from restarting node, after reestablishing RSVP communication with a
the restarting node. restarted node which supports the recovery procedures defined in
Section 4.5.2 of this document.
The new message is called the RecoveryPath message. The message The new message is called the RecoveryPath message. The message
conveys the contents of the last received Path message back to the conveys the contents of the last received Path message back to the
restarting node. The restarting node can use the RecoveryPath restarting node. The restarting node can use the RecoveryPath
message along with the state in the received Path message to message along with the state in the received Path message to
associate control and data plane state and to validate the forwarding associate control and data plane state and to validate the forwarding
state with the state presented by the neighboring RSVP nodes. state with the state presented by the neighboring RSVP nodes.
The restarting node indicates its desire to receive and process the
RecoveryPath message by including a new object called the Capability
object with the RecoveryPath Desired bit set, in its Hello messages
sent to the downstream RSVP neighbor. The downstream RSVP neighbor
can indicate its ability to send RecoveryPath messages by including
the Capability object with the RecoveryPath Transmit Enabled set in
its Hello messages to the restarting node. Thus, both the restarting
node and its RSVP neighbor, with the help of the Capability object,
can detect if the RecoveryPath message extensions defined in this
document can be used to recover signaling state after a restart.
If the restarting node is a transit node, it will receive a Path If the restarting node is a transit node, it will receive a Path
message with a Recovery Label object from its upstream RSVP neighbor. message with a Recovery Label object from its upstream RSVP neighbor.
In addition, the RecoveryPath message allows such transit nodes to In addition, the RecoveryPath message allows such transit nodes to
reconstruct any state that was previously dynamically constructed by reconstruct any state that was previously dynamically constructed by
the node, e.g., ERO sub-objects. If the restarting node is an the node, e.g., ERO sub-objects. If the restarting node is an
ingress node, all significant signaling state can be recovered based ingress node, all significant signaling state can be recovered based
on the RecoveryPath message. on the RecoveryPath message.
Selective transmission of the RecoveryPath message is supported by Selective transmission of the RecoveryPath message is supported by
enhancing the Summary Refresh mechanisms defined in [RFC2961]. When enhancing the Summary Refresh mechanisms defined in [RFC2961]. When
Recovery Summary Refresh is supported, the restarting node can select Recovery Summary Refresh is supported, the restarting node can select
the LSP's for which it would like to receive RecoveryPath messages. the LSPs for which it would like to receive RecoveryPath messages.
This is useful when the restarting node is able to locally recover This is useful when the restarting node is able to locally recover
the signaling state for a subset of the previously active LSP's. the signaling state for a subset of the previously active LSPs.
Restarting egress nodes, and Resv message processing are not impacted Restarting egress nodes, and Resv message processing are not impacted
by the presented extensions, see [RFC3473] for details. by the presented extensions, see [RFC3473] for details.
2. Extensions to Nodal Fault Handling 4. Extensions to Nodal Fault Handling
This section presents the protocol modifications to Section 9 of This section presents the protocol modifications to Section 9 of
[RFC3473]. [RFC3473].
2.1. RecoveryPath Message Format 4.1 RecoveryPath Message Format
The format of a RecoveryPath message is the same as the format of a The format of a RecoveryPath message is the same as the format of a
Path message as defined in [RFC3473]: Path message as defined in [RFC3473]:
<RecoveryPath Message> ::= <Path Message> <RecoveryPath Message> ::= <Path Message>
The destination address used in the IP header of a RecoveryPath The destination address used in the IP header of a RecoveryPath
message MUST be the same as the destination address used in the IP message MUST be the same as the destination address used in the IP
header of the corresponding Resv message last generated by the header of the corresponding Resv message last generated by the
sending node. Except as specified below all objects in a sending node. Except as specified below all objects in a
RecoveryPath message are identical to the objects in the RecoveryPath message are identical to the objects in the
corresponding Path message last received by the sending node. corresponding Path message last received by the sending node.
2.2. Related Procedures 4.2 Capability Object
Capability objects are carried in RSVP Hello messages. The
Capability object uses Class-Number TBA (of form 10bbbbbb) and C-Type
of 1.
The message format of a Hello message is modified to be:
<Hello Message> ::= <Common Header> [ <INTEGRITY> ] <HELLO>
[ <RESTART_CAP> ] [ <CAPABILITY> ]
The format of a Capability object is:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Class-Num(TBA)| C-Type (1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |T|R|S|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
RecoveryPath Desired (R): 1 bit
When set (1), indicates that the sending node desires to
receive RecoveryPath messages. Absence of the Capability
object MUST be treated as if the R-bit is cleared (0).
RecoveryPath Transmit Enabled (T): 1 bit
When set (1), indicates that the sending node is enabled to
send RecoveryPath messages. Absence of the Capability object
MUST be treated as if the T-bit is cleared (0).
RecoveryPath Srefresh Capable (S): 1 bit
When set (1) along with the R-bit, indicates that the sending
node is capable of receiving and processing Srefresh messages
with the RecoveryPath Flag set (1) in the MESSAGE_ID LIST
object. Absence of the Capability object MUST be treated as if
the S-bit is cleared (0). Related procedures are defined in
Section 5.2.1.
Reserved bits
Reserved bits MUST be set to zero on transmission and MUST be
ignored on receipt.
4.2.1 Conformance
All nodes supporting the extensions defined in this document MUST be
able to transmit, and, properly receive and process RecoveryPath
messages. All nodes MUST be able to set both the T and R bits. Both
the T and R bits SHOULD be set (1) by default. A node MAY allow
RecoveryPath message transmission and reception to be independently
disabled based on local policy. When RecoveryPath message
transmission is disabled, the T-bit MUST be set to zero (0). When
RecoveryPath message reception is not desired, the R-bit MUST be set
to zero (0).
Any node that supports the extensions defined in this document and
sets the Refresh-Reduction-Capable bit [RFC2961], SHOULD support
setting of the S-bit and support the mechanisms defined in Section 5.
4.3 Related Procedures
This document does not modify existing procedures for sending and This document does not modify existing procedures for sending and
receiving RSVP Hello messages as defined in [RFC3209] and the receiving RSVP Hello messages as defined in [RFC3209] and the
Restart_Caps object in RSVP Hello messages as defined in [RFC3473]. Restart_Caps object in RSVP Hello messages as defined in [RFC3473].
The procedures for control channel faults are defined in [RFC3473] The procedures for control channel faults are defined in [RFC3473]
and are not changed by this document. and are not changed by this document.
The presented extensions require the use of RSVP Hellos as defined in The presented extensions require the use of RSVP Hellos as defined in
[RFC3209] and the use of the Restart_Caps object extension as defined [RFC3209] and the use of the Restart_Caps object extension as defined
in [RFC3473]. The presented extensions address only "Nodal Faults" in [RFC3473]. The presented extensions address only "Nodal Faults"
skipping to change at page 6, line 5 skipping to change at page 8, line 31
in [RFC3473]. in [RFC3473].
Note: There are no changes to the procedures defined in Section 9.5.3 Note: There are no changes to the procedures defined in Section 9.5.3
in [RFC3473] (Procedures for the Neighbor of a Restarting node). in [RFC3473] (Procedures for the Neighbor of a Restarting node).
There are no changes to the procedures defined in Section 9.5.2 in There are no changes to the procedures defined in Section 9.5.2 in
[RFC3473] if the restarting node is an egress node. [RFC3473] if the restarting node is an egress node.
The following sections assume previously defined procedures are The following sections assume previously defined procedures are
followed, except where explicitly modified. followed, except where explicitly modified.
2.3. Procedures For The Downstream Neighbor 4.4 Procedures for the Capability Object
4.4.1 Procedures for the Downstream Neighbor
If the downstream RSVP neighbor of a restarting node is capable of
sending RecoveryPath messages to the restarting node, it MUST include
the Capability object with the RecoveryPath Transmit Enabled (T) bit
set (1) in all its Hello messages sent to the restarting node.
If the downstream RSVP neighbor receives Hello messages from a
restarting node, with the Restart_Caps object as defined in
[RFC3473], and, with the Capability object with the RecoveryPath
Desired (R) bit set (1), it MUST treat the restarting node as capable
of receiving and processing RecoveryPath messages as defined in this
document.
If the downstream RSVP neighbor receives a Capability object in a
Hello message with the RecoveryPath Desired (R) bit set (1), but,
without the Restart_Caps object, it MUST process the Hello message as
if the RecoveryPath Receive Desired (R) bit is cleared (0) in the
Hello message.
If the downstream RSVP neighbor does not receive the Capability
object in Hello messages sent by the restarting node or the
RecoveryPath Desired (R) bit is cleared (0) in the Capability object,
it MUST treat the restarting node as not capable of supporting the
RecoveryPath message procedures defined in this document, and, MUST
revert to recovery procedures as defined in [RFC3473].
4.4.2 Procedures for the Restarting Node
A restarting node that expects to recover RSVP state by the receipt
and processing of RecoveryPath messages according to procedures
defined in this document, MUST include the Capability object with the
RecoveryPath Desired (R) bit set (1) in its RSVP Hello messages to
its neighbors, during the Recovery Period. The node MUST also
include the Restart_Caps object as defined in [RFC3473], in all those
Hello messages.
If the Recovery Time is zero (0) or the restarting node does not
support/desire the use of RecoveryPath messages, the RecoveryPath
Desired (R) bit MUST be cleared (0) in the Capability object included
in Hello messages, or the Capability object MAY be omitted from Hello
messages sent by the restarting node.
During the Recovery Period, if the restarting node receives Hello
messages from a downstream RSVP neighbor with the RecoveryPath
Transmit Enabled (T) bit set (1) in the Capability object and the
Restart_Caps object as defined in [RFC3473], it MUST treat the
downstream RSVP neighbor as capable of sending RecoveryPath messages
according to procedures defined in Section 4.5.1. If the restarting
node expects to recover RSVP state by the receipt and processing of
RecoveryPath messages, it MUST follow procedures defined in
Section 4.5.2, with the downstream RSVP neighbor.
During the Recovery Period, if the restarting node receives Hello
messages from a downstream RSVP neighbor with the RecoveryPath
Transmit Enabled (T) bit cleared (0) in the Capability object, or,
with the Capability object not present, it MUST treat the downstream
RSVP neighbor as not capable of the RecoveryPath message procedures
defined in this document, and, it MUST revert to the recovery
procedures defined in [RFC3473] immediately, with the downstream RSVP
neighbor.
4.5 Procedures for the RecoveryPath message
4.5.1 Procedures For The Downstream Neighbor
After a downstream RSVP neighbor has detected that its upstream node After a downstream RSVP neighbor has detected that its upstream node
has restarted and is capable of recovery as defined in [RFC3473], the has restarted, is capable of recovery as defined in [RFC3473], and,
downstream RSVP neighbor MUST send a RecoveryPath message for each is capable of receiving RecoveryPath messages as defined in
LSP associated with the restarting node for which it has sent a Resv Section 4.4, the downstream RSVP neighbor MUST send a RecoveryPath
message. message for each LSP associated with the restarting node for which it
has sent a Resv message. During the Recovery Period, if the
downstream RSVP neighbor detects that the restarting node is not
capable of receiving RecoveryPath messages, by the absence of the
Capability object or the RecoveryPath Desired (R) bit cleared (0) in
the Capability object in the restarting node's Hello messages, the
downstream RSVP neighbor SHOULD NOT send the RecoveryPath messages to
the restarting node.
The RecoveryPath message is constructed by copying all objects from The RecoveryPath message is constructed by copying all objects from
the last received associated Path message, with the following the last received associated Path message, with the following
exceptions: exceptions:
The MESSAGE_ID, MESSAGE_ID_ACK and MESSAGE_ID_NACK objects are not The MESSAGE_ID, MESSAGE_ID_ACK and MESSAGE_ID_NACK objects are not
copied. Any MESSAGE_ID, MESSAGE_ID_ACK and MESSAGE_ID_NACK copied. Any MESSAGE_ID, MESSAGE_ID_ACK and MESSAGE_ID_NACK
objects used in RecoveryPath messages are generated based on objects used in RecoveryPath messages are generated based on
procedures defined in [RFC2961]. procedures defined in [RFC2961].
skipping to change at page 6, line 37 skipping to change at page 10, line 39
message sent to the restarted node, for the LSP being recovered. message sent to the restarted node, for the LSP being recovered.
In the sender descriptor, the Recovery Label object MUST be In the sender descriptor, the Recovery Label object MUST be
included, with the label value copied from the label value in the included, with the label value copied from the label value in the
Label object in the most recent associated Resv message sent to Label object in the most recent associated Resv message sent to
the restarted node, for the LSP being recovered. the restarted node, for the LSP being recovered.
All other objects from the most recent received Path message MUST be All other objects from the most recent received Path message MUST be
included in the RecoveryPath message. included in the RecoveryPath message.
All RecoveryPath messages SHOULD be sent within approximately 1/2 of All RecoveryPath messages SHOULD be sent at least once within
the Recovery Time advertised by the restarted neighbor. If there are approximately 1/2 of the Recovery Time advertised by the restarted
many LSP's to be recovered by the restarted node, the downstream RSVP neighbor. If there are many LSPs to be recovered by the restarted
neighbor should avoid sending RecoveryPath messages in a short time node, the downstream RSVP neighbor should avoid sending RecoveryPath
interval, to avoid overloading the restarted node's CPU. Instead it messages in a short time interval, to avoid overloading the restarted
should spread the messages across 1/2 the Recovery Time interval. node's CPU. Instead it should spread the messages across 1/2 the
Recovery Time interval.
After sending a RecoveryPath message and during the Recovery Period, After sending a RecoveryPath message and during the Recovery Period,
the node SHOULD periodically re-send the RecoveryPath message until the node SHOULD periodically re-send the RecoveryPath message until
it receives a corresponding response. A corresponding response is a it receives a corresponding response. A corresponding response is a
Message ID acknowledgment or a Path message for the LSP the Message ID acknowledgment or a Path message for the LSP the
RecoveryPath message represents. Each such re-send attempt is at the RecoveryPath message represents. Each such re-send attempt is at the
end of any Message ID rapid retransmissions, if the Message ID end of any Message ID rapid retransmissions, if the Message ID
mechanism is used. If the Message ID mechanim is not in use, the mechanism is used. If the Message ID mechanim is not in use, the
period between re-send attempts SHOULD be such that at least 3 period between re-send attempts SHOULD be such that at least 3
attempts are completed before the expiry of 1/2 the Recovery Time attempts are completed before the expiry of 3/4 the Recovery Time
interval. Each such re-send attempt MUST treat the RecoveryPath interval. Each such re-send attempt MUST treat the RecoveryPath
message as a new message, and update the MESSAGE_ID object according message as a new message, and update the MESSAGE_ID object according
to procedures defined in [RFC2961]. Note, per [RFC3473], Resv to procedures defined in [RFC2961]. Note, per [RFC3473], Resv
messages are suppressed during this recovery period until a messages are suppressed during this recovery period until a
corresponding Path message is received. corresponding Path message is received.
2.4. Procedures for the Restarting Node 4.5.2 Procedures for the Restarting Node
These procedures apply during the "state recovery process" and These procedures apply during the "state recovery process" and
"Recovery Period" as defined in Section 9.5.2 in [RFC3473]. Any "Recovery Period" as defined in Section 9.5.2 in [RFC3473]. Any
RecoveryPath message received after the Recovery Period has expired RecoveryPath message received after the Recovery Period has expired
MUST be discarded. If no LSP state matching the RecoveryPath message MUST be discarded. If no LSP state matching the RecoveryPath message
is located, the restarted node MAY send a PathTear message is located, the restarted node MAY send a PathTear message
constructed from the RecoveryPath message, to expedite the cleanup of constructed from the RecoveryPath message, to expedite the cleanup of
unrecovered RSVP and associated forwarding state downstream of the unrecovered RSVP and associated forwarding state downstream of the
restarted node. restarted node.
skipping to change at page 7, line 35 skipping to change at page 11, line 39
Signaling state may be recovered from sources other than the Signaling state may be recovered from sources other than the
mechanisms defined in this document. The restarting node SHOULD mechanisms defined in this document. The restarting node SHOULD
consider signaling state as resynchronized for all such LSPs and consider signaling state as resynchronized for all such LSPs and
follow corresponding procedures defined below. Further, recovery follow corresponding procedures defined below. Further, recovery
procedures defined below may be overridden by local policy. procedures defined below may be overridden by local policy.
Again, there are no changes to the procedures defined in Section Again, there are no changes to the procedures defined in Section
9.5.2 in [RFC3473] if the restarting node is an egress node. 9.5.2 in [RFC3473] if the restarting node is an egress node.
2.4.1. Path and RecoveryPath Message Procedures 4.5.2.1 Path and RecoveryPath Message Procedures
When a node receives a RecoveryPath message during the Recovery When a node receives a RecoveryPath message during the Recovery
Period, the node first checks if it has resynchronized RSVP state Period, the node first checks if it has resynchronized RSVP state
associated with the message. If there is resynchronized state, and associated with the message. If there is resynchronized state, and
when both reliable message delivery [RFC2961] is supported and a when both reliable message delivery [RFC2961] is supported and a
MESSAGE_ID object is present in the RecoveryPath message, the node MESSAGE_ID object is present in the RecoveryPath message, the node
MUST follow Message ID acknowledgment procedures as defined in MUST follow Message ID acknowledgment procedures as defined in
[RFC2961], and, consider the message as processed. If there is [RFC2961], and, consider the message as processed. If there is
resynchronized state, and, there is no MESSAGE_ID object or reliable resynchronized state, and, there is no MESSAGE_ID object or reliable
message delivery [RFC2961] is not supported, the node SHOULD send a message delivery [RFC2961] is not supported, the node SHOULD send a
triggered Path message, and, consider the message as processed. trigger Path message, and, consider the message as processed.
If non-resynchronized state is found or the node is the ingress, the If non-resynchronized state is found or the node is the ingress, the
node saves the information contained in the RecoveryPath message and node saves the information contained in the RecoveryPath message and
continues with processing as defined in Section 2.4.2. continues with processing as defined in Section 4.5.2.2.
If no associated RSVP state is found and the node is not the ingress If no associated RSVP state is found and the node is not the ingress
node, the node saves the information contained in the RecoveryPath node, the node saves the information contained in the RecoveryPath
message for later use. message for later use.
Note the following modifies Section 9.5.2 of [RFC3473]: Note the following modifies Section 9.5.2 of [RFC3473]:
When a node receives a Path message during the Recovery Period, the When a node receives a Path message during the Recovery Period, the
node first locates any RSVP state associated with the message. If node first locates any RSVP state associated with the message. If
resynchronized RSVP state is found, then the node handles this resynchronized RSVP state is found, then the node handles this
message according to previously defined procedures. message according to previously defined procedures.
If non-resynchronized state is found, the node saves the information If non-resynchronized state is found, the node saves the information
contained in the Path message including the Recovery_Label object and contained in the Path message including the Recovery_Label object and
continues with processing as defined in Section 2.4.2. continues with processing as defined in Section 4.5.2.2.
Per [RFC3473], if matching RSVP state is not found, and the message Per [RFC3473], if matching RSVP state is not found, and the message
does not carry a Recovery_Label object, the node treats this as a does not carry a Recovery_Label object, the node treats this as a
setup for a new LSP, and handles it according to previously defined setup for a new LSP, and handles it according to previously defined
procedures. procedures.
If matching RSVP state is not found, and the message carries a If matching RSVP state is not found, and the message carries a
Recovery_Label object, the node saves the information contained in Recovery_Label object, the node saves the information contained in
the Path message including the Recovery_Label object for later use. the Path message including the Recovery_Label object for later use.
2.4.2. Re-Synchronization Procedures 4.5.2.2 Re-Synchronization Procedures
After receipt of the RecoveryPath message and, for non-ingress LSPs, After receipt of the RecoveryPath message and, for non-ingress LSPs,
the corresponding Path message with a Recovery Label object, the the corresponding Path message with a Recovery Label object, the
restarting node SHOULD locate and associate corresponding forwarding restarting node SHOULD locate and associate corresponding forwarding
state using the received information. The restarting node associates state using the received information. The restarting node associates
the corresponding active forwarding plane state from the following the corresponding active forwarding plane state from the following
signaled information: signaled information:
The upstream data interface is recovered from the RSVP HOP object The upstream data interface is recovered from the RSVP HOP object
in the received Path message. in the received Path message.
skipping to change at page 9, line 10 skipping to change at page 13, line 12
The downstream data interface is recovered from the RSVP HOP The downstream data interface is recovered from the RSVP HOP
object in the received RecoveryPath message. object in the received RecoveryPath message.
The label on the downstream data interface is recovered from the The label on the downstream data interface is recovered from the
Recovery Label object in the received RecoveryPath message. If Recovery Label object in the received RecoveryPath message. If
the LSP is bidirectional, the label for the upstream direction is the LSP is bidirectional, the label for the upstream direction is
recovered from the Upstream Label object in the RecoveryPath recovered from the Upstream Label object in the RecoveryPath
message. message.
If complete forwarding state is located, the restarted node MUST If complete forwarding state is located, the restarted node MUST
treat the LSP as resynchronized and MUST send a triggered Path treat the LSP as resynchronized and MUST send a trigger Path message
message downstream. The Explicit Route object in the Path message downstream. The Explicit Route object in the Path message SHOULD
SHOULD match the Explicit Route object received in the RecoveryPath match the Explicit Route object received in the RecoveryPath message.
message. In addition, the restarted node SHOULD recover state from In addition, the restarted node SHOULD recover state from the other
the other objects received in the RecoveryPath message. Optimally objects received in the RecoveryPath message. Optimally the
the resulting Path message should not cause any redundant or resulting Path message should not cause any redundant or unnecessary
unnecessary re-processing of state along the remaining downstream re-processing of state along the remaining downstream nodes.
nodes. Ideally, except for MESSAGE_ID processing and recovery Ideally, except for MESSAGE_ID processing and recovery processing,
processing, the transmitted Path message will be treated as a refresh the transmitted Path message will be treated as a refresh by the
by the downstream RSVP neighbor (and hence should not trigger any downstream RSVP neighbor (and hence should not trigger any generation
generation of Path messages with changed state further downstream). of Path messages with changed state further downstream).
If no forwarding state is located, the node treats the path message If no forwarding state is located, the node treats the path message
as a setup for a new LSP. The outgoing interface and label(s) as a setup for a new LSP. The outgoing interface and label(s)
indicated in the RecoveryPath message SHOULD be reused, when indicated in the RecoveryPath message SHOULD be reused, when
possible. All other information contained in the RecoveryPath possible. All other information contained in the RecoveryPath
message MAY also be used. message MAY also be used.
2.4.3. Procedures on Expiration of Recovery Period 4.5.2.3 Procedures on Expiration of Recovery Period
There are several cleanup steps to follow at the end of the Recovery There are several cleanup steps to follow at the end of the Recovery
Period. At the end of the Recovery Period, any state that was Period. At the end of the Recovery Period, any state that was
installed as the result of a received RecoveryPath message that is installed as the result of a received RecoveryPath message that is
not resynchronized SHOULD be discarded. not resynchronized SHOULD be discarded.
Any Path messages that were received containing a Recovery_Label that Any Path messages that were received containing a Recovery_Label that
have not been resynchronized, SHOULD be treated as being received have not been resynchronized, MUST be treated as being received
during the Recovery Period and processed as per [RFC3473]. during the Recovery Period and processed as per [RFC3473].
Per [RFC3473], any other state that is not resynchronized during the Per [RFC3473], any other state that is not resynchronized during the
Recovery Period SHOULD be removed at the end of the Period. Recovery Period SHOULD be removed at the end of the Period.
2.5. Compatibility 4.6 Compatibility
This document introduces a new RSVP signaling message to be generated This document introduces a new RSVP signaling message called the
by the downstream RSVP neighbor of a restarting node. RecoveryPath message to be generated by the downstream RSVP neighbor
of a restarting node. To advertise the capability of sending and
receiving RecoveryPath messages, this document introduces the
Capability object, to be included in Hello messages by a restarting
node and its downstream RSVP neighbors.
If the restarting node does not support the RecoveryPath message and If a restarting node does not support the Capability object, it will
associated procedures, it will discard all received RecoveryPath discard the object as the Class-Number is of the form 10bbbbbb and
messages, and revert to recovery processing as defined in [RFC3473]. revert to recovery processing as defined in [RFC3473]. The
restarting node will not include the Capability object in its Hello
messages. Hence, all downstream RSVP neighbors detect that the
restarting node is not capable of supporting the extensions defined
in this document, will not send the RecoveryPath messages to the
restarting node, and, will revert to recovery processing as defined
in [RFC3473].
If the downstream RSVP neighbor does not support the RecoveryPath If a downstream RSVP neighbor does not support the Capability object,
message and associated procedures, the restarting node processes it will discard the object received in Hello messages and revert to
received Path messages as defined in Section 2.4.3, which essentially recovery processing as defined in [RFC3473]. The downstream RSVP
reverts to the processing defined in [RFC3473]. neighbor will not include the Capability object in its Hello
messages. Hence, the restarting node will detect that the downstream
RSVP neighbor is not capable of supporting the extensions defined in
this document, and, will revert to recovery processing as defined in
[RFC3473].
3. RecoveryPath Summary Refresh 5. RecoveryPath Summary Refresh
This section describes a mechanism to control which LSP state is This section describes a mechanism to control which LSP state is
communicated in RecoveryPath messages. This mechanism enhances the communicated in RecoveryPath messages. This mechanism enhances the
Summary Refresh mechanism defined in [RFC2961], and uses a new object Summary Refresh mechanism defined in [RFC2961], and uses the
carried in the Hello message defined in [RFC3209] and [RFC3473]. The RecoveryPath Srefresh Capable (S) bit in the Capability object as
described mechanism is referred to as RecoveryPath Summary Refresh. defined in Section 4.2, carried in the Hello message defined in
[RFC3209] and [RFC3473]. The described mechanism is referred to as
RecoveryPath Summary Refresh.
Selective transmission of RecoveryPath messages is controlled much Selective transmission of RecoveryPath messages is controlled much
the same way transmission of Path or Resv messages is controlled with the same way transmission of Path or Resv messages is controlled with
standard Summary Refresh, see [RFC2961]. In standard Summary standard Summary Refresh, see [RFC2961]. In standard Summary
Refresh, an Srefresh message is sent by a node to identify to its Refresh, an Srefresh message is sent by a node to identify to its
neighbor about Path and Resv state that is locally installed and neighbor about Path and Resv state that is locally installed and
available. The receiver of the Srefresh message, can then attempt to available. The receiver of the Srefresh message, can then attempt to
locate matching Path and Resv state. If no matching state is found, locate matching Path and Resv state. If no matching state is found,
the receiver can request that the missing state be sent to it, by the receiver can request that the missing state be sent to it, by
sending an Srefresh NACK to the sender of the Srefresh message. When sending an Srefresh NACK to the sender of the Srefresh message. When
skipping to change at page 10, line 39 skipping to change at page 15, line 6
state in this process. state in this process.
The mechanism described in this section extends the Summary Refresh The mechanism described in this section extends the Summary Refresh
process to the Path state that can be represented in RecoveryPath process to the Path state that can be represented in RecoveryPath
messages. In this case, the Srefresh messages represent previously messages. In this case, the Srefresh messages represent previously
received Path messages, rather than previously transmitted Path received Path messages, rather than previously transmitted Path
messages. This is the primary difference between standard Summary messages. This is the primary difference between standard Summary
Refresh and RecoveryPath Summary Refresh described in this section. Refresh and RecoveryPath Summary Refresh described in this section.
When a node restarts, and is capable of supporting the mechanisms When a node restarts, and is capable of supporting the mechanisms
described in this section, it includes a new object in Hello messages described in this section, it includes the Capability object with the
it sends to its RSVP neighbors. The new object is defined below in RecoveryPath Desired (R) bit set and the RecoveryPath Srefresh
Section 3.2 and is called the Capability object. A bit carried Capable (S) bit set in Hello messages it sends to its RSVP neighbors.
within the Capability object indicates when a restarting node desires
its downstream neighbor to use the mechanisms described in this
section. This bit is called the RecoveryPath Srefresh Capable bit.
When a neighbor of the restarting node detects a restart, see When a neighbor of the restarting node detects a restart, see
[RFC3209], it detects that the restarted node is requesting [RFC3209], it detects that the restarted node is capable of receiving
RecoveryPath Srefresh messages by the presence of the Capability RecoveryPath messages as defined in Section 4.4, and that the
object with the RecoveryPath Srefresh Capable bit set. When such an restarted node is requesting RecoveryPath Srefresh messages by the
indication is found, the neighbor generates one or more Srefresh RecoveryPath Srefresh Capable (S) bit set in the Capability object.
messages. Each message indicates the Path state that can be When such an indication is found, the neighbor generates one or more
Srefresh messages. Each message indicates the Path state that can be
represented in a RecoveryPath message. Within such Srefresh represented in a RecoveryPath message. Within such Srefresh
messages, Path state that can be represented in RecoveryPath messages messages, Path state that can be represented in RecoveryPath messages
is represented using MESSAGE_ID information, and this information is is represented using MESSAGE_ID information, and this information is
communicated within MESSAGE_ID LIST objects. To indicate that the communicated within MESSAGE_ID LIST objects. To indicate that the
MESSAGE_ID LIST object is for recovery purposes, a new flag is set in MESSAGE_ID LIST object is for recovery purposes, a new flag is set in
the MESSAGE_ID LIST object. This flag is called the RecoveryPath the MESSAGE_ID LIST object. This flag is called the RecoveryPath
Flag and is defined below. Flag and is defined below.
The restarted node can then use the Srefresh message and the The restarted node can then use the Srefresh message and the
MESSAGE_ID LIST object to try to identify matching transmitted Path MESSAGE_ID LIST object to try to identify matching transmitted Path
state. The node identifies local state by matching Epoch and Message state. The node identifies local state by matching Epoch and Message
ID tuples against Path messages transmitted downstream prior to the ID tuples against Path messages transmitted downstream prior to the
restart. restart.
If matching state is located, then the restarted node operates as if If matching state is located, then the restarted node operates as if
a RecoveryPath message has been received, per Section 2.4. If no a RecoveryPath message has been received, per Section 4.5.2. If no
matching state can be located, the restarted node generates a matching state can be located, the restarted node generates a
Srefresh NACK, see Section 5.4 of [RFC2961]. The Srefresh NACK is Srefresh NACK, see Section 5.4 of [RFC2961]. The Srefresh NACK is
also marked with the new RecoveryPath Flag to indicate that the NACK also marked with the new RecoveryPath Flag to indicate that the NACK
is related to RecoveryPath messages. is related to RecoveryPath messages.
Upon receiving a Srefresh NACK, the downstream node generates a Upon receiving a Srefresh NACK, the downstream node generates a
RecoveryPath message for the Path state indicated by each entry in RecoveryPath message for the Path state indicated by each entry in
the MESSAGE_ID LIST. The procedures defined above in Section 2 are the MESSAGE_ID LIST. The procedures defined above in Section 4 are
then followed by the restarted node and the downstream RSVP neighbor. then followed by the restarted node and the downstream RSVP neighbor.
3.1. MESSAGE_ID ACK/NACK and MESSAGE_ID LIST Objects 5.1 MESSAGE_ID ACK/NACK and MESSAGE_ID LIST Objects
The MESSAGE_ID ACK/NACK objects and the MESSAGE_ID LIST object, The MESSAGE_ID ACK/NACK objects and the MESSAGE_ID LIST object,
defined in [RFC2961], are updated by this document. A new bit within defined in [RFC2961], are updated by this document. A new bit within
the existing Flags field of each object is defined. This bit the existing Flags field of each object is defined. This bit
indicates that the object carries MESSAGE_ID information related to indicates that the object carries MESSAGE_ID information related to
Path state that can be recovered using RecoveryPath messages. The Path state that can be recovered using RecoveryPath messages. The
same flag value is used in all the objects for consistency. same flag value is used in all the objects for consistency.
MESSAGE_ID_ACK object MESSAGE_ID_ACK object
MESSAGE_ID_NACK object MESSAGE_ID_NACK object
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See Section 5.1 of [RFC2961] for definition of other fields. See Section 5.1 of [RFC2961] for definition of other fields.
Flags: 8 bits Flags: 8 bits
0x02: RecoveryPath Flag 0x02: RecoveryPath Flag
Indicates that the associated object carries MESSAGE_ID Indicates that the associated object carries MESSAGE_ID
information related to one or more Path messages that can be information related to one or more Path messages that can be
recovered using a RecoveryPath message. recovered using a RecoveryPath message.
3.2. Capability Object 5.2 RecoveryPath Srefresh Capable bit
Capability objects are carried in RSVP Hello messages. The
Capability object uses Class-Number TBA (of form 10bbbbbb) and C-Type
of 1.
The message format of a Hello message is modified to be:
<Hello Message> ::= <Common Header> [ <INTEGRITY> ] <HELLO>
[ <RESTART_CAP> ] [ <CAPABILITY> ]
The format of a Capability object is: The Capability object and the RecoveryPath Srefresh Capable (S) bit
are defined in Section 4.2.
0 1 2 3 5.2.1 Procedures
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Class-Num(TBA)| C-Type (1) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
RecoveryPath Srefresh Capable (R): 1 bit
When set (1), indicates that the sending node is capable of To support the selective receipt of RecoveryPath messages as defined
receiving and processing Srefresh messages with the in this section, a restarting node MUST support the receipt and
RecoveryPath Flag set (1) in the MESSAGE_ID LIST object. processing of RecoveryPath messages as defined in Section 4.5.2 and
Absence of the Capability object MUST be treated as if the MUST indicate this capability by including the Capability object with
R-bit is cleared (0). the RecoveryPath Desired (R) bit set as defined in Section 4.4.2 in
its Hello messages.
Reserved bits To indicate to an RSVP neighbor that selective transmission of
RecoveryPath messages is desired, a restarting node MUST set (1) the
S-bit in the Capability object in all Hello messages it sends during
the Recovery Period to the neighbor. When the restarting node does
not desire the receipt of RecoveryPath messages, see Section 4.4.2,
or, the selective transmission mechanism defined in this section, it
MUST clear (0) the S-bit in the Capability object if included in
Hello messages.
Reserved bits MUST be set to zero on transmission and MUST be The downstream RSVP neighbor checks the R-bit and the S-bit upon
ignored on receipt. detecting a restart of a node that supports state recovery with
RecoveryPath messages. Detection of neighbor restarts with state
recovery using RecoveryPath messages is defined in Section 4. If
both the R-bit and the S-bit are set, then the procedures defined
below in Section 5.3.1 MUST be followed. If the S-bit is cleared,
the downstream RSVP neighbor MUST revert to normal procedures defined
in Section 4.5.1. If the R-bit is cleared, but the S-bit is set, the
downstream RSVP neighbor MUST treat as if the Capability object was
received with the S-bit cleared. See Section 4.4 for handling of
Hello messages without the Capability object.
3.2.1. Procedures 5.2.2 Compatibility
The Capability object is sent within a Hello message to indicate that There are no compatibility issues introduced in the procedures
a node supports selective transmission of RecoveryPath messages. To defined in Section 5.2.1.
indicate to a neighbor that selective transmission of RecoveryPath
messages is desired, a restarting node MUST include the Capability
object with the R-bit set (1) in all Hello messages it sends during
the Recovery Period to the neighbor. When either the Restart_Cap
Object is not present in a Hello message or when the Recovery Time is
zero (0), the Capability object MUST be omitted or the R-bit MUST be
cleared (0).
On the downstream neighbor, the R-bit is checked upon detecting a The restarting node will detect that its neighbor does not support
restart of a neighbor that supports state recovery. Detection of selective transmission of RecoveryPath messages when a RecoveryPath
neighbor restarts with state recovery is defined in [RFC3473]. When message is received prior to the receipt of a Srefresh message
a node supports RecoveryPath Summary Refresh, and it detects a containing a MESSAGE_ID LIST object with the RecoveryPath Flag set
restart of a neighbor that supports state recovery, it MUST check to (1). When this occurs, any received RecoveryPath messages MUST be
see if the received Hello message contains a Capability object with processed as defined in Section 4.
the R-bit set. If the R-bit is set, then the procedures defined
below in Section 3.3.1 MUST be followed. If the Capability object is
not found or the R-bit not set, then the node MUST revert to normal
recovery procedures as defined above in Section 2.3.
3.2.2. Compatibility 5.3 RecoveryPath Summary Refresh Procedures
There are no compatibility issues introduced in this section. The Related processing occurs in the following logical order:
use of the Capability object will not cause any issues on a
non-supporting receiver as it uses a Class-Number of form 10bbbbbb.
The object will simply be ignored, and normal processing will
continue. Normal processing includes procedures defined above in
Section 2, in [RFC3473] and in [RFC3209].
The sender of the Capability object will detect that its neighbor o Generation of RecoveryPath-related Srefresh messages
does not support selective transmission of RecoveryPath messages when
a RecoveryPath message is received prior to the receipt of a Srefresh
message containing a MESSAGE_ID LIST object with the RecoveryPath
Flag set (1). When this occurs, any received RecoveryPath messages
MUST be processed as defined above in Section 2.
3.3. RecoveryPath Summary Refresh Procedures o RecoveryPath-related Srefresh message receive processing and NACK
generation
Related processing occurs in the following logical order: o Message ID NACK receive processing and generation of RecoveryPath
messages
o Generation of RecoveryPath-related Srefresh messages
o RecoveryPath-related Srefresh message receive processing and
NACK generation
o Message ID NACK receive processing and generation of
RecoveryPath messages
o Receive processing of RecoveryPath messages o Receive processing of RecoveryPath messages
Actual processing MAY result in the above occurring in an interlaced Actual processing MAY result in the above occurring in an interlaced
fashion when multiple LSP's are being recovered. Both the restarted fashion when multiple LSPs are being recovered. Both the restarted
node and the downstream RSVP neighbor MUST be able to process in this node and the downstream RSVP neighbor MUST be able to process in this
fashion. fashion.
3.3.1. Generation of RecoveryPath-related Srefresh Messages 5.3.1 Generation of RecoveryPath-related Srefresh Messages
A neighbor of a restarting node generates one or more A neighbor of a restarting node generates one or more RecoveryPath-
RecoveryPath-related Srefresh messages when the R-bit is set in the related Srefresh messages when the S-bit is set in the restarted
restarted node's Hello messages as described above in Section 3.2.1. node's Hello messages as described in Section 5.2.1. The procedures
The procedures for generating an Srefresh message are defined in for generating an Srefresh message are defined in [RFC2961]. Only
[RFC2961]. Only modifications to these procedures are described in modifications to these procedures are described in this section.
this section. Also, Srefresh message transmit and receive processing may occur
simultaneously during the Recovery Period and are not impacted by the
procedures defined in this section.
To generate RecoveryPath-related Srefresh messages, a node must To generate RecoveryPath-related Srefresh messages, a node must
identify which Path state can be represented in RecoveryPath messages identify which Path state can be represented in RecoveryPath messages
and which Srefresh message or messages can be used to carry the and which Srefresh message or messages can be used to carry the
related information. As previously mentioned, the Path state that related information. As previously mentioned, the Path state that
can be represented in RecoveryPath messages is indicated in Srefresh can be represented in RecoveryPath messages is indicated in Srefresh
messages using the MESSAGE_ID information from the most recently messages using the MESSAGE_ID information from the most recently
received Path message associated with the state. received Path message associated with the state.
After processing the R-bit as described in Section 3.2.1, the node After processing the S-bit as described in Section 5.2.1, the node
identifies all state associated with Path messages received from the identifies all state associated with Path messages received from the
restarted neighbor. Only Path state that has not been updated since restarted neighbor. Only Path state that has not been updated since
the restart may be represented in the Srefresh messages. Received the restart may be represented in the Srefresh messages. Received
Path state containing a MESSAGE_ID object whose Epoch value matches Path state containing a MESSAGE_ID object whose Epoch value matches
the Epoch received in the most recent Hello message is considered as the Epoch received in the most recent Hello message is considered as
updated after the upstream neighbor has restarted. Such Path state updated after the upstream neighbor has restarted. Such Path state
MUST NOT be represented in the Srefresh messages. MUST NOT be represented in the Srefresh messages. Each Srefresh
message contains one or more MESSAGE_ID LIST objects. Each such
Each Srefresh message contains one or more MESSAGE_ID LIST objects. MESSAGE_ID LIST object MUST have the RecoveryPath Flag set (1).
Each such MESSAGE_ID LIST object MUST have the RecoveryPath Flag set Multiple MESSAGE_ID LIST objects MAY be included in order to
(1). Multiple MESSAGE_ID LIST objects MAY be included in order to
accommodate multiple Epoch values. The MESSAGE_ID LIST objects accommodate multiple Epoch values. The MESSAGE_ID LIST objects
represent the identified, non-updated, Path state. A represent the identified, non-updated, Path state. A
Message_Identifier field created for each identified, non-updated Message_Identifier field created for each identified, non-updated
Path state MUST be included in an appropriate MESSAGE_ID LIST object. Path state MUST be included in an appropriate MESSAGE_ID LIST object.
The Message_Identifier field is created based on the MESSAGE_ID The Message_Identifier field is created based on the MESSAGE_ID
object from the most recently received Path message associated with object from the most recently received Path message associated with
identified Path state. If any identified Path state does not have an identified Path state. If any identified Path state does not have an
associated MESSAGE_ID object, this state MUST be processed as defined associated MESSAGE_ID object, this state MUST be processed as defined
above in Section 2.3. above in Section 4.5.1.
The source IP address for the Srefresh message SHOULD be the source The source IP address for the Srefresh message SHOULD be the source
IP address in the IP header of the corresponding Resv messages IP address in the IP header of the corresponding Resv messages
previously sent to the restarted node. The Srefresh message SHOULD previously sent to the restarted node. The Srefresh message SHOULD
be destined to the IP address in the HOP object in the corresponding be destined to the IP address in the HOP object in the corresponding
Path messages. This may result in multiple Srefresh messages being Path messages. This may result in multiple Srefresh messages being
generated. Per [RFC2961], implementations may choose to limit each generated. Per [RFC2961], implementations may choose to limit each
Srefresh message to the MTU size of the outgoing link, and to not Srefresh message to the MTU size of the outgoing link, and to not
bundle Srefresh messages. RecoveryPath-related Srefresh messages bundle Srefresh messages. RecoveryPath-related Srefresh messages
SHOULD be sent using reliable delivery, as defined in [RFC2961]. SHOULD be sent using reliable delivery, as defined in [RFC2961].
During the Recovery Period, unacknowledged RecoveryPath-related During the Recovery Period, unacknowledged RecoveryPath-related
Srefresh messages SHOULD be periodically transmitted. The Srefresh messages SHOULD be periodically transmitted. The
retransmission algorithm used can be same algorithm used for retransmission algorithm used can be same algorithm used for
retransmitting RecoveryPath messages during the Recovery Period (see retransmitting RecoveryPath messages during the Recovery Period (see
section 2.3). Note that prior to each such periodic retransmission, Section 4.5.1). Note that prior to each such periodic
the Srefresh message SHOULD be updated to exclude the Message ID's of retransmission, the Srefresh message SHOULD be updated to exclude the
Path state that has been updated by the receipt of a Path message. Message ID's of Path state that has been updated by the receipt of a
Path message.
To allow sufficient processing time for the restarted node, the To allow sufficient processing time for the restarted node, the
downstream RSVP neighbor MAY choose to generate multiple downstream RSVP neighbor MAY choose to generate multiple
RecoveryPath-related Srefresh messages containing partial but RecoveryPath-related Srefresh messages containing partial but
mutually exclusive sets of Message Identifiers spread across 1/4 of mutually exclusive sets of Message Identifiers spread across 1/4 of
the Recovery Time advertised by the restarted node. the Recovery Time advertised by the restarted node.
3.3.2. RecoveryPath-related Srefresh Receive Processing and NACK 5.3.2 RecoveryPath-related Srefresh Receive Processing and NACK
Generation Generation
Upon receiving an Srefresh message containing a MESSAGE_ID LIST Upon receiving an Srefresh message containing a MESSAGE_ID LIST
object with the RecoveryPath Flag set), the restarted node attempts object with the RecoveryPath Flag set), the restarted node attempts
to locate matching previously transmitted Path state. The Epoch in to locate matching previously transmitted Path state. The Epoch in
the MESSAGE_ID LIST object along with each Message Identifier in the the MESSAGE_ID LIST object along with each Message Identifier in the
object is used to match against the MESSAGE_ID object in Path object is used to match against the MESSAGE_ID object in Path
messages previously transmitted to the downstream RSVP neighbor. For messages previously transmitted to the downstream RSVP neighbor. For
each Message Identifier in the MESSAGE_ID LIST: each Message Identifier in the MESSAGE_ID LIST:
If matching transmitted Path state is found, the restarting node If matching transmitted Path state is found, the restarting node
treats the corresponding LSP state as having received and treats the corresponding LSP state as having received and
processed a RecoveryPath message, and, perform any further processed a RecoveryPath message, and, perform any further
processing necessary as defined in Section 2.4. Specifically, it processing necessary as defined in Section 4.5.2. Specifically,
MUST generate a triggered Path message for the LSP as defined in it MUST generate a trigger Path message for the LSP as defined in
Section 2.4.2. The restarted node MAY spread the transmission of Section 4.5.2.2. The restarted node MAY spread the transmission
such triggered Path messages across 1/2 of the remaining Recovery of such trigger Path messages across 1/2 of the remaining Recovery
Period to allow the downstream RSVP neighbor sufficient processing Period to allow the downstream RSVP neighbor sufficient processing
time. time.
If matching transmitted Path state is not found, the restarting If matching transmitted Path state is not found, the restarting
node MUST generate a MESSAGE_ID NACK as defined in [RFC2961]. node MUST generate a MESSAGE_ID NACK as defined in [RFC2961].
Each generated MESSAGE_ID NACK MUST have the RecoveryPath Flag set Each generated MESSAGE_ID NACK MUST have the RecoveryPath Flag set
(1). (1).
It is recommended that the restarted node combine multiple such It is recommended that the restarted node combine multiple such
MESSAGE_ID NACK's into a single ACK message, per [RFC2961]. MESSAGE_ID NACK's into a single ACK message, per [RFC2961].
3.3.3. RecoveryPath-related MESSAGE_ID NACK Receive Processing 5.3.3 RecoveryPath-related MESSAGE_ID NACK Receive Processing
This section defines the procedures associated with the processing of This section defines the procedures associated with the processing of
received MESSAGE_ID NACK's which have the RecoveryPath Flag set (1). received MESSAGE_ID NACK's which have the RecoveryPath Flag set (1).
Procedures for processing of MESSAGE_ID NACK's without the Procedures for processing of MESSAGE_ID NACK's without the
RecoveryPath Flag present are defined in [RFC2961] and not modified RecoveryPath Flag present are defined in [RFC2961] and not modified
in this document. Processing of MESSAGE_ID NACK's with the in this document. Processing of MESSAGE_ID NACK's with the
RecoveryPath Flag set (1) also follows procedures defined in RecoveryPath Flag set (1) also follows procedures defined in
[RFC2961] unless explicitly modified in this section. [RFC2961] unless explicitly modified in this section.
For each MESSAGE_ID NACK with the RecoveryPath Flag set (1), the For each MESSAGE_ID NACK with the RecoveryPath Flag set (1), the
downstream RSVP neighbor must locate the matching received Path downstream RSVP neighbor must locate the matching received Path
message. If a matching Path message is found, the downstream RSVP message. If a matching Path message is found, the downstream RSVP
neighbor MUST generate a RecoveryPath message as defined in Section neighbor MUST generate a RecoveryPath message as defined in
2.3. If a matching Path message is not found, the MESSAGE_ID NACK is Section 4.5.1. If a matching Path message is not found, the
ignored. An example where this may occur is when the restarted node MESSAGE_ID NACK is ignored. An example where this may occur is when
has already generated an updated Path message after its restart. the restarted node has already generated an updated Path message
after its restart.
4. Acknowledgments
The authors would like to thank participants of the CCAMP WG for
comments and suggestions. Also thanks to Arthi Ayyangar, Adrian
Farrel and Nick Neate for their helpful comments and feedback.
5. Security Considerations 6. Security Considerations
This document introduces a new RSVP message that is restricted to one This document introduces a new RSVP message that is restricted to one
RSVP hop. This document introduces no new security considerations RSVP hop. This document introduces no new security considerations
beyond those already addressed for existing RSVP hop-by-hop messages. beyond those already addressed for existing RSVP hop-by-hop messages.
This document introduces a new RSVP object to be included in RSVP This document introduces a new RSVP object to be included in RSVP
Hello messages. This document introduces no new security Hello messages. This document introduces no new security
considerations beyond those already addressed for existing objects in considerations beyond those already addressed for existing objects in
RSVP Hello messages. RSVP Hello messages.
6. IANA Considerations This document introduces new procedures to be performed on RSVP
agents that neighbor a restarting RSVP agent. In situations where
the control plane in general and the RSVP agent in particular of a
node carrying one or more LSPs is restarted due to external attacks,
the procedures introduced in this document provide the ability for
the restarting RSVP agent to recover the RSVP state corresponding to
the LSPs with the least possible perturbation to the rest of the
network. Ideally, only the neighboring RSVP agents should notice the
restart and hence need to perform additional processing. This allows
for a network with active LSPs to recover LSP state gracefully from
an external attack, without perturbing the data/forwarding plane
state.
A new RSVP message type is defined in this document. The RSVP The procedures defined in this document introduce additional
message type is TBA by IANA. processing overhead for the RSVP agents that neighbor a restarting
RSVP agent. If an RSVP agent restarts due to external attacks, such
added processing on the neighboring RSVP agents may impact their
ability to perform other control plane tasks including any processing
for other LSPs that do not involve the restarting node. Such impact
can be minimalized by the restarting RSVP agent using a large enough
Recovery Time, so that its neighbors are provided sufficient time to
handle the additional processing involved while continuing to perform
their other control plane functions normally during the Recovery
Period.
A new RSVP object of form 10bbbbbb is defined in this document. The 7. Acknowledgments
Class-Num is TBA by IANA.
7. References The authors would like to thank participants of the CCAMP WG for
comments and suggestions. Also thanks to Arthi Ayyangar, Adrian
Farrel and Nick Neate for their helpful comments and feedback.
7.1. Normative References 8. IANA Considerations
[RFC2119] "Key words for use in RFCs to Indicate Requirement Levels", [RFC2205] defines the Class-Number name space for RSVP objects. The
RFC 2119, S. Bradner, March 1997. name space is managed by IANA.
[RFC2205] "Resource ReSerVation Protocol (RSVP) - Version 1, A new RSVP object using a Class-Number of form 10bbbbbb called the
Functional Specification", Capability Object is defined in Section 4.2 in this document. The
RFC 2205, Braden, et al, September 1997. Class-Number is TBA by IANA.
[RFC2747] "RSVP Cryptographic Authentication", A new RSVP message type called a RecoveryPath message is defined in
RFC 2747, F. Baker, et al, January 2000. Section 4.1 of this document. The RSVP message type is TBA by IANA.
[RFC2961] "RSVP Refresh Overhead Reduction Extensions", This document creates a new name space in the Capability object
RFC 2961, L. Berger, et al, April 2001. defined in Section 4.2. The new name space is a 32 bit-wide field.
New registrations in this name space are to be allocated by IANA
through an IETF Consensus action, per [RFC2434]. IANA also serves as
the repository for this name space.
[RFC3209] "Extensions to RSVP for LSP Tunnels", D. Awduche, et al, Section 4.2 defines the following bits in the 32-bit field of the
RFC 3209, December 2001. Capability Object, TBA by IANA:
[RFC3471] "Generalized Multi-Protocol Label Switching (GMPLS) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Signaling Functional Description", | |S|P|R|
RFC 3471, L. Berger, et al, January 2003. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
[RFC3473] "Generalized Multi-Protocol Label Switching (GMPLS) RecoveryPath Transmit Enabled (T): 1 bit
Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions",
RFC 3473, L. Berger, et al, January 2003.
7.2. Informative References RecoveryPath Desired (R): 1 bit
[RESTART] "RSVP Graceful Restart Extensions", RecoveryPath Srefresh Capable (S): 1 bit
draft-rahman-rsvp-restart-extensions-00,
R. Rahman, et al, October 2003
8. Authors' Addresses 9. Normative References
Arun Satyanarayana [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC2747] Baker, F., Lindell, B., and M. Talwar, "RSVP Cryptographic
Authentication", RFC 2747, January 2000.
[RFC2961] Berger, L., Gan, D., Swallow, G., Pan, P., Tommasi, F.,
and S. Molendini, "RSVP Refresh Overhead Reduction
Extensions", RFC 2961, April 2001.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Functional Description", RFC 3471,
January 2003.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
Authors' Addresses
Arun Satyanarayana (editor)
Cisco Systems, Inc. Cisco Systems, Inc.
170 West Tasman Dr. 170 West Tasman Dr.
San Jose, CA 95134 San Jose, CA 95134
USA
Phone: +1 408 853-3206 Phone: +1 408 853-3206
Email: asatyana@cisco.com Email: asatyana@cisco.com
Reshad Rahman (editor)
Cisco Systems, Inc.
2000 Innovation Dr.
Kanata, Ontario K2K 3E8
Canada
Phone: 613 254-3519
Email: rrahman@cisco.com
Lou Berger Lou Berger
Movaz Networks, Inc. Movaz Networks, Inc.
7926 Jones Branch Drive 7926 Jones Branch Drive
Suite 615 Suite 615
McLean VA, 22102 McLean, VA 22102
USA
Phone: +1 703 847-1801 Phone: +1 703 847-1801
Email: lberger@movaz.com Email: lberger@movaz.com
Dimitri Papadimitriou (Alcatel) Dimitri Papadimitriou
Alcatel
Francis Wellesplein 1 Francis Wellesplein 1
B-2018 Antwerpen, Belgium B-2018 Antwerpen
Belgium
Phone: +32 3 240-8491 Phone: +32 3 240-8491
Email: dimitri.papadimitriou@alcatel.be Email: dimitri.papadimitriou@alcatel.be
Reshad Rahman
Cisco Systems Inc.
2000 Innovation Dr.,
Kanata, Ontario, K2K 3E8
Canada.
Phone: (613)-254-3519
Email: rrahman@cisco.com
Anca Zamfir Anca Zamfir
Cisco Systems Inc. Cisco Systems, Inc.
2000 Innovation Dr., 2000 Innovation Dr.
Kanata, Ontario, K2K 3E8 Kanata, Ontario K2K 3E8
Canada. Canada
Phone: (613)-254-3484
Phone: 613 254-3484
Email: ancaz@cisco.com Email: ancaz@cisco.com
Junaid Israr Junaid Israr
Cisco Systems Inc. Cisco Systems, Inc.
2000 Innovation Dr., 2000 Innovation Dr.
Kanata, Ontario, K2K 3E8 Kanata, Ontario K2K 3E8
Canada. Canada
Phone: (613)-254-3693
Phone: 613 254-3693
Email: jisrar@cisco.com Email: jisrar@cisco.com
9. Intellectual Property Considerations Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
skipping to change at page 20, line 5 skipping to change at page 24, line 29
such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at this standard. Please address the information to the IETF at
ietf-ipr@ietf.org. ietf-ipr@ietf.org.
10. Disclaimer of Validity Disclaimer of Validity
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
11. Full Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2004). This document is subject Copyright (C) The Internet Society (2005). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
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