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draft-ietf-ccamp-gmpls-segment-recovery
Network Working Group Louis Berger (Movaz Networks)
Internet Draft Igor Bryskin (Movaz Networks)
Expiration Date: August 2004 Dimitri Papadimitriou (Alcatel)
Adrian Farrel (Old Dog Consulting)
February 2004
GMPLS Based Segment Recovery
draft-berger-ccamp-gmpls-segment-recovery-00.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
To view the current status of any Internet-Draft, please check the
"1id-abstracts.txt" listing contained in an Internet-Drafts Shadow
Directory, see http://www.ietf.org/shadow.html.
Abstract
This document describes protocol specific procedures for GMPLS
(Generalized Multi-Protocol Label Switching) RSVP-TE (Resource
ReserVation Protocol - Traffic Engineering) signaling extensions to
support LSP segment protection and restoration. These extensions are
intended to be compliment and be consistent with the Extensions for
End-to-End GMPLS-based Recovery. Implications and interactions with
Fast Reroute are also addressed.
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Contents
1 Introduction .............................................. 3
2 Segment Recovery .......................................... 4
2.1 Segment Protection ........................................ 6
2.2 Segment Re-routing and Restoration ........................ 6
3 Association Object ........................................ 6
3.1 Format .................................................... 7
3.2 Procedures ................................................ 7
3.2.1 Resource Sharing Association Type Processing .............. 7
4 Explicit Control of LSP Segment Recovery .................. 8
4.1 Secondary Explicit Route Object Format .................... 8
4.1.1 Protection Subobject ...................................... 8
4.2 Explicit Control Procedures ............................... 9
4.2.1 Resv Message Processing ................................... 10
4.2.2 Branch Failure Handling ................................... 11
4.2.3 Admin Status Change ....................................... 11
4.2.4 Recovery LSP Tear Down .................................... 12
4.3 Tear Down From Non-Ingress Nodes .......................... 12
4.3.1 Modified Notify Request Object Processing ................. 13
4.3.2 Modified Notify and Error Message Processing .............. 13
5 Secondary Record Route Objects ............................ 14
5.1 Format .................................................... 14
5.2 Path Processing ........................................... 14
5.3 Resv Processing ........................................... 14
6 Dynamic Control of LSP Segment Recovery ................... 15
6.1 Modified Protection Object Format ......................... 15
6.2 Dynamic Control Procedures ................................ 16
7 Additional Fast Reroute Considerations .................... 17
8 Updated RSVP Message Formats .............................. 17
9 Security Considerations ................................... 19
10 IANA Considerations ....................................... 20
11 Intellectual Property Considerations ...................... 20
12 References ................................................ 21
12.1 Normative References ...................................... 21
12.2 Informative References .................................... 21
13 Contributors .............................................. 22
14 Full Copyright Statement .................................. 22
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Conventions used in this document
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 RFC 2119 [RFC2119].
In addition, the reader is assumed to be familiar with the
terminology used in [RFC3209], [RFC3471], [RFC3473] as well as
[TERM], [FUNCT], [E2E-RECOVERY] and [FRR].
1. Introduction
[TERM] covers multiple types of protection, including end-to-end and
segment based approaches. [E2E-RECOVERY], RSVP-TE Extensions in
support of End-to-End GMPLS-based Recovery, defines a set of
extensions to support multiple types of recovery. The supported
types include 1+1 unidirectional/ 1+1 bi-directional protection, LSP
protection with extra-traffic (including 1:N protection with extra-
traffic), pre-planned LSP re- routing without extra-traffic
(including shared mesh), and full LSP re-routing. In all cases, the
recovery is provided on an end-to-end basis, i.e., the ingress and
egress nodes of both the protected and the protecting LSP are the
same.
[FRR] provides a form of segment recovery for packet MPLS-TE
networks. Two methods of Fast Reroute are defined in [FRR]. The
one-to-one backup method creates detour LSPs for each protected LSP
at each potential point of local repair. The facility backup method
creates a bypass tunnel to protect a potential failure point which is
shared by multiple LSPs and uses label stacking. Neither approach
supports the full set of recovery types supported by [E2E-RECOVERY].
Additionally, the facility backup method is not applicable to most
non-PSC (packet) switching technologies.
The extensions defined in this document allow for support of the full
set of recovery types supported by [E2E-RECOVERY] on a segment, or
portion of the LSP, basis. The extensions allow (a) the signaling of
desired LSP segment protection type, (b) upstream nodes to optionally
identify where segment protection starts and stops, and (c) to also
optionally identify hops used on protection segments. These
extensions are intended to be compatible with, and in some cases used
with Fast Reroute.
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2. Segment Recovery
Segment recovery is used to provide protection and restoration over a
portion of an end-to-end LSP. Such segment protection and
restoration is useful to protect against a span failure, a node
failure, or failure over a particularly portion of a network used by
an LSP.
Consider the following topology:
A---B---C---D---E---F
\ /
G---I
In this topology, end-to-end protection and recovery is not possible
for an LSP going between node A and node F, but it is possible to
protect/recover a portion of the LSP. Specifically, if the LSP uses
a working path of [A,B,C,D,E,F] then a protection or restoration LSP
can be established along the path [C,G,I,E]. This LSP protects
against failures on spans {C,D} and {D,E} as well as a failure of
node D. This form of protection/restoration is referred to as
Segment Protection and Segment Restoration, or Segment Recovery
collectively. The LSP providing the protection or restoration is
referred to as a segment protection LSP or a segment restoration LSP.
The term segment recovery LSP is used to cover either a segment
protection LSP or a segment restoration LSP. The term branch node is
used to refer to a node that initiates a recovery LSP, e.g., node C
in the figure shown above. This is equivalent to the point of local
repair (PLR) used in [FRR]. As with [FRR], the term merge node is
used to refer to a node that terminates a recovery LSP, e.g., node E
in the figure shown above.
Segment protection or restoration is signaled using a working LSP and
one or more segment recovery LSPs. Each segment recovery LSP is
signaled as an independent LSP. Specifically, the Sender_Template
object uses the IP address of the node originating the recovery path,
e.g., node C in the topology shown above, and the Session object
contains the IP address of the node terminating the recovery path,
e.g., node E shown above. There is no specific requirement on LSP ID
value, Tunnel ID and Extended Tunnel ID. Values for these fields are
selected normally, including consideration for make-before-break.
Intermediate nodes follow standard signaling procedures when
processing segment recovery LSPs. A segment recovery LSP may be
protected itself using segment or end-to-end protection/restoration.
Note, in PSC environments it may be desirable to construct the
Sender_Template and Session objects per [FRR].
When [FRR] isn't being used, the association between segment recovery
LSPs with other LSPs is indicated using the Association object
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defined in [E2E-RECOVERY]. The Association object is used to
associate recovery LSPs with the LSP they are protecting. Working
and protecting LSPs, as well as primary and secondary LSPs, are
identified using LSP Status as described in [E2E-RECOVERY]. The
0-bit in the segment flags portion of the Protection object is used
to identify when a recovery LSP is carrying the normal (active)
traffic.
An upstream node can permit downstream nodes to dynamically identify
branch and merge points by setting the desired LSP segment protection
bits in the Protection object. These bits are defined below.
Optionally, an upstream node, usually the ingress node, can identify
the endpoints of a segment recovery LSP. This is accomplished using
a new object. This object uses the same format as an ERO and is
referred to as a Secondary Explicit Route object or SERO, see section
4.1. SEROs also support a new subobject to indicate the type of
protection or restoration to be provided. At a minimum an SERO will
indicate a recovery LSP's initiator, protection/restoration type and
terminator. Standard ERO semantics, see [RFC3209], can optionally be
used within and SERO to explicitly control the recovery LSP. A
Secondary Record Route object or SRRO is defined for recording the
path of a segment recovery LSP, see section 5.
SEROs are carried between the node creating the SERO, typically the
ingress, and the node initiating a recovery LSP. The node initiating
a recovery LSP uses the SERO to create the ERO for the recovery LSP.
At this (branch) node, all local objects are removed, and the new
protection subobject is used to create the Protection object for the
recovery LSP. SRROs are carried in Path messages between the node
terminating a recovery LSP, the merge node, and the egress. SRROs
are used in Resv messages between a branch node and the ingress. The
merge node of a recovery LSP creates an SRRO by copying the RRO from
the Path message of the associated recovery LSP into a new SRRO
object. Any SRROs present in the recovery LSP's Path message are
also copied. The branch node of a recovery LSP creates an SRRO by
copying the RRO from the Resv message of associated recovery LSP into
a new SRRO object. Any SRROs present in the recovery LSP's Resv
message are also copied.
Notify request processing is also impacted by LSP segment recovery.
Per [RFC3473], only one Notify Request object is meaningful and
should be propagated. Additional Notify Request objects are used to
identify recovery LSP branch nodes.
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2.1. Segment Protection
Three approaches of end-to-end protection are defined in [E2E-
RECOVERY]: 1+1 Unidirectional Protection, see Section 5; 1+1 Bi-
directional Protection, see Section 6: and 1:1 Protection With Extra
Traffic, see Section 7. The segment protection forms of these
protection approaches all operate much like their end-to-end
counterparts. Each behaves just like there end-to-end counterparts,
with the exception that the protection LSP protects only a portion of
the working LSP. The type of protection to be used on a segment
protection LSP is indicated, to the protection LSP's ingress, using
the protection SERO subobject defined in Section 4.1.
The switch-over processing for segment 1+1 Bi-directional protection
and 1:1 Protection With Extra Traffic follows the same procedures as
end-to-end protection forms, see Section 6.2 and Section 7.2 for
details.
2.2. Segment Re-routing and Restoration
Three re-routing and restoration approaches are defined [E2E-
RECOVERY]: Re-routing without Extra-Traffic, see Section 8; Shared-
Mesh Restoration, see Section 9; (Full) LSP Re-routing, see Section
11. As with protection, these approaches are supported on a segment
basis. The segment forms of re-routing and restoration operate
exactly like their end-to-end counterparts, with the exception that
the restoration LSP recovers only a portion of the working LSP. The
type of re-routing or restoration to be used on a segment restoration
LSP is indicated, to the restoration LSP's ingress, using the new
protection SERO subobject.
3. Association Object
The Association object is used association of segment protection LSPs
when [FRR] isn't being used. The Association object is defined in
[E2E-RECOVERY]. In this document we define a new type to support
make before break, formats and procedures defined in [E2E-RECOVERY]
are not otherwise modified.
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3.1. Format
Association Type: 16 bits
Value Type
----- ----
2 Resource Sharing (R)
See [E2E-RECOVERY] for the definition of other fields and other
values.
3.2. Procedures
The Association object is used to associate different LSPs with each
other. In the protection and restoration context, the object is used
to associate a recovery LSP with the LSP it is protecting. It is
also used to support resource sharing during make-before-break. This
object MUST NOT be used when association is made according to the
methods defined in [FRR].
3.2.1. Resource Sharing Association Type Processing
The Association object with an Association Type with the value
Resource Sharing is used to enable resource sharing during make-
before-break. Resource sharing during make-before-break is defined
in [RFC3209]. The defined support only works with LSPs that share
the same LSP egress. With the introduction of segment recovery LSPs,
it is now possible for an LSP end-point to change during make-before-
break.
A node includes an Association object with a Resource Sharing
Association Type in outgoing an Path message when it wishes to
indicate resource sharing across an associated set of LSPs. The
Association Source is set to the branch node's router address. The
Association ID MUST be set to a value that uniquely identifies the
association of LSPs. This MAY be set to the upstream LSP's LSP ID.
Once included, an Association object with a Resource Sharing
Association Type SHOULD NOT be removed from the Path messages
associated with an LSP.
When a node is branching an LSP and the associated upstream Path
messages is received with an Association object with a Resource
Sharing type, the branch node inserts a new Association object with a
Resource Sharing type in the Path message of the new LSP. The
Association Source is set to the branch node's router address. The
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Association ID MUST be set to a value that uniquely identifies the
association of LSPs. This MAY be set to the recovery LSP's LSP ID.
Any node processing a Path message for which it does not have
matching state, and which contains a Association object with a
Resource Sharing type, examines existing LSPs for matching
Association Type, Association Source and Association ID values. If
any match is found, then [RFC3209] style resource sharing SHOULD be
provided between the new and old LSPs. See [RFC3209] for additional
details.
4. Explicit Control of LSP Segment Recovery
Secondary Explicit Route objects, or SEROs, may be used to indicate
the branch and merge nodes of recovery LSPs. They may also provide
additional information that is to be carried in a recovery LSP's ERO.
When upstream control of branch and merge nodes are not desired,
SEROs are not used.
4.1. Secondary Explicit Route Object Format
The format of a SECONDARY_EXPLICIT_ROUTE object is the same as an
EXPLICIT_ROUTE object. This includes the definition of subobjects
defined for EXPLICIT_ROUTE object. The class of the
SECONDARY_EXPLICIT_ROUTE object is TBA (of form 11bbbbbb).
4.1.1. Protection Subobject
The protection subobject is not valid for use with the Explicit and
Record Route objects and MUST NOT be included in those objects.
The format of the Protection Subobject is defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved | C-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PROTECTION Object Contents |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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L-bit
This is defined in [RFC3209] and MUST be set to zero for
protection subobjects.
Type
37 Protection
C-Type
The C-Type of the included Protection object.
PROTECTION Object Contents
The contents of the Protection object with the format matching
the indicated C-Type, excluding the object header.
4.2. Explicit Control Procedures
SEROs are carried in Path messages and indicate at which node a
recovery LSP is to be initiated relative to the LSP carrying the
SERO. More than one SERO MAY be present in a Path message.
To indicate the branch and merge nodes of a recovery LSPs, an SERO is
created and added to the Path message of the LSP being recovered.
The decision to create and insert an SERO is a local matter and
outside the scope of this document.
An SERO SHOULD contain at least three subobjects. The first
subobject MUST indicate the node that is to originate the recovery
LSP, i.e. the segment branch node. The address used SHOULD also be
listed in the ERO or another SERO. This ensures that the branch node
is along the LSP path. The second subobject SHOULD be a protection
subobject and should indicate the protection or restoration to be
provided by the recovery LSP. When the protection subobject is
present, the LSP Segment Recovery Flags in the Protection subobject
MUST be ignored. The final subobject in the SERO MUST be the merge
node of the recovery LSP, and MAY have the L-bit set. Standard ERO
subobjects MAY be inserted between the protection subobject and the
final subobject. These subobjects MAY be loose or strict.
A node receiving a Path message containing one or more SEROs SHOULD
examine each SERO to see if it indicates a local branch point. This
determination is made by examining the first object of each SERO and
seeing if the address indicated in the subobject can be associated
with the local node. If any of indicated addresses are associated
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with the local node, then the local node is a branch node. If the
local node is not a branch node, all received SEROs MUST be
transmitted, without modification, in the corresponding outgoing Path
message.
At a branch node, the SERO together with the Path message of LSP
being recovered provides the information to create the recovery LSP.
If the processing node is unable to support the requested branch, a
PathErr message SHOULD sent for the LSP being being protected, and
normal processing of the LSP continues. The PathErr message SHOULD
indicate an error of "TBD" and the Path_State_Removed flag MUST NOT
be set. If no error is generated then a recovery LSP is created.
The Path message for the recovery LSP is created at the branch node
by cloning the objects carried in the incoming Path message of the
LSP being protected. Certain objects are replaced or modified in the
recovery LSP's outgoing Path message. The Sender_template MUST be
updated to use an address on the local node, and the LSP ID MUST be
updated to ensure uniqueness. The Session object MUST be updated to
use the address indicated in the final subobject of the SERO as the
tunnel endpoint, the tunnel ID MAY be updated, and the extended
tunnel ID MUST be set to the local node. The Protection object is
replaced with the contents of the matching SERO subobject, when
present. Any RROs and EROs present in the incoming Path message MUST
NOT be included in the recovery LSP. A new ERO MUST be included,
with the contents of the SERO that indicated a local branch. As with
all EROs, no local information (local address and any protection
subobjects) is carried in the ERO carried in the recovery LSP's
outgoing Path message. The SERO that indicated a local branch MUST
be omitted from the recovery LSP's outgoing Path message. Note, by
default all other received SEROs are passed in the recovery LSP's
outgoing Path message. SEROs MAY be omitted, from the recovery LSP's
outgoing Path message as well as the outgoing Path message for the
LSP being protected when the SERO does not relate to the outgoing
path message.
The resulting Path message is used to create the recovery LSP. From
this point on, Standard Path message processing is used in processing
the resulting Path message.
4.2.1. Resv Message Processing
Branch nodes will process Resv messages for both recovery LSPs and
LSPs being protected. Resv messages are propagated upstream of branch
nodes only after a Resv message is received for the protected LSP.
Resv messages on recovery LSPs will typically not trigger
transmission of upstream Resv messages (for the LSP being protected).
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Exceptions to this include when RROs/SRROs are being collected and
during certain Admin Status object processing. See below for more
information on related processing.
4.2.2. Branch Failure Handling
During setup and during normal operation, PathErr messages may be
received at a branch node. In all cases, a received PathErr message
is first processed per standard processing rules. When the PathErr
messages is not on a recovery LSP and the Path_State_Removed flag is
set, then any recovery LSPs associated with the LSP MUST also be torn
down.
If the PathErr messages is on a recovery LSP, receipt of the PathErr
message SHOULD trigger the generation of a PathErr message upstream
on the associated LSP. This outgoing (upstream) PathErr message
SHOULD be sent with the Path_State_Removed flag cleared (0) as only
the recovery LSP is impacted. However, if a branch node sends a
PathErr message with the Path_State_Removed flag set (1), which is
not recommended, the node MUST send a PathTear message downstream on
all other branches.
Additionally, an outgoing PathErr message MUST include any SEROs
carried in a received PathErr message. If no SERO is present in a
received PathErr message, then an SERO that matches the errored LSP
MUST be added to the outgoing PathErr message.
4.2.3. Admin Status Change
In general, objects in a recovery LSP are created based on the
corresponding objects in the LSP being protected. The Admin Status
object is created the same way, but it also requires some special
coordination at branch nodes. Specifically, in addition to normal
processing, a branch node that receives an Admin Status object in a
Path message also MUST relay the Admin Status object in a Path on
every recovery LSP. All Path messages MAY be concurrently sent
downstream.
Downstream nodes process the change in the Admin Status object per
[RFC3473], including generation of Resv messages. When the most
recently received upstream Admin Status object had the R bit set,
branch nodes wait for a Resv message with a matching Admin Status
object to be received on all branches before relaying a corresponding
Resv message upstream.
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4.2.4. Recovery LSP Tear Down
Recovery LSP removal is follows standard the standard procedures
defined in [RFC3209] and [RFC3473]. This includes without and with
setting the administrative status.
4.2.4.1. Tear Down Without Admin Status Change
The node initiating the tear down originates a PathTear message.
Each node that receives a PathTear message process the PathTear
message per standard processing, see [RFC3209] and [RFC2205], and
also relays a PathTear on every recovery LSP. All PathTear messages
(received from upstream and locally originated) may be concurrently
sent downstream.
4.2.4.2. Tear Down With Admin Status Change
Per [RFC3473], the ingress node originates a Path message with the D
and R bits set in the Admin Status object. The admin status change
procedure defined above, see Section 4.2.3, MUST then be followed.
Once the ingress receives all expected Resv messages MUST follow the
tear down procedure described in the Section 4.2.4.
4.3. Tear Down From Non-Ingress Nodes
As with any LSP, any node along a recovery LSP may initiate removal
of the recovery LSP. To do this, the node initiating the tear down
sends a PathErr message with the appropriate Error Code and the
Path_State_Removed flag cleared (0) toward the LSP ingress. As
described above, the recovery LSP ingress will propagate the error to
the LSP ingress which can then signal the removal of the recovery
LSP.
It is also possible for the node initiating the tear down to remove a
Recovery LSP in a non-graceful manner. In this case, the initiator
sends a PathTear message downstream and a PathErr message with Error
Code TBD and the Path_State_Removed flag set (1) toward the LSP
ingress node. This manner of non-ingress node tear down is NOT
RECOMMENDED as it can result in the removal of the LSP being
protected in some case.
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4.3.1. Modified Notify Request Object Processing
When a node is branching a recovery LSP, it SHOULD include a single
Notify Request object on the recovery LSP. The notify node address
MUST be set to the router address of the branch node. Normal
notification procedures are then followed for the recovery LSP.
Under local policy control, a node issuing a Notify message MAY also
send a Notify message to the Notify Node Address indicated in the
last, or any other, Notify_Request object received.
A branch node SHOULD also add a Notify Request object to the LSP
being protected. The notify node address is set to the address used
in the sender template of the recovery LSP. A locally added Notify
Request object MUST be listed first in the outgoing message, any
received Notify Request object MUST then be listed in the message in
the order that they were received.
Recovery LSP merge nodes remove the object added by the recovery
branch node from outgoing Path messages for the LSP being protected.
This is done by removing the Notify Request object that matches the
source address of the recovery LSP. Note, to cover certain backwards
compatibility scenarios the Notify Request object SHOULD NOT be
removed if it is the sole Notify Request object.
Note this requires the following change to [RFC3473], Section 4.2.1:
- old text:
If a message contains multiple Notify_Request objects, only the first
object is meaningful. Subsequent Notify_Request objects MAY be
ignored and SHOULD NOT be propagated.
- new text:
If a message contains multiple Notify_Request objects, only the first
object used is in notification. Subsequent Notify_Request objects
MUST be propagated in the order received.
4.3.2. Modified Notify and Error Message Processing
Branch nodes MUST support the following modification to Notify
message processing. When a branch node receives notification of an
LSP failure and it is unable to recover from that failure, it MUST
notify the node indicated in the first Notify_Request object received
in the Path message associated with the LSP.
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5. Secondary Record Route Objects
Secondary Record Route objects, or SRROs, are used to record the path
used by recovery LSPs.
5.1. Format
The format of a SECONDARY_RECORD_ROUTE object is the same as an
RECORD_ROUTE object, Class number 21. This includes the definition
of subobjects defined for RECORD_ROUTE object. The class of the
SECONDARY_RECORD_ROUTE object is TBA (of form 11bbbbbb).
The protection subobject defined in [E2E-RECOVERY] can also be used
in SECONDARY_RECORD_ROUTE objects.
5.2. Path Processing
SRROs may be carried in Path messages and indicate the presence of
upstream recovery LSPs. More than one SRRO MAY be add and present in
a Path message.
Any received SRRO, MUST be transmitted by transit nodes, without
modification, in the corresponding outgoing Path message.
SRROs are inserted in Path messages by recovery LSP merge nodes. The
SRRO is created by copying the contents of an RRO received the
recovery LSP into a new SRRO object. This SRRO is added to the
outgoing Path message of the recovered LSP. Note multiple SRROs may
be present. The collection of SRROs is controlled via the segment-
recording-desired flag in the SESSION_ATTRIBUTE object. This flag MAY
be set even when SEROs are not used.
5.3. Resv Processing
SRROs may be carried in Resv messages and indicate the presence of
downstream recovery LSPs. More than one SRRO MAY be add and present
in a Resv message.
Any received SRRO, MUST be transmitted by transit nodes, without
modification, in the corresponding outgoing Resv message. When Resv
messages are merged, the resulting merged Resv should contain all
SRROs received in downstream Resv messages.
SRROs are inserted in Resv messages by branch nodes of recovery LSPs.
The SRRO is created with the first two objects being the local node
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address followed by a protection subobject with the contents of the
recovery LSP's Protection object. The remainder of the SRRO is
created by copying the contents of the RRO received the recovery LSP.
This SRRO is added to the outgoing Resv message of the recovered LSP.
Again, multiple SRROs may be present.
6. Dynamic Control of LSP Segment Recovery
Dynamic identification of branch and merge nodes is supported via the
LSP Segment Recovery Flags carried in the Protection object. The LSP
Segment Recovery Flags are carried within one of Reserved fields
defined in the Protection object defined in [E2E-RECOVERY]. LSP
Segment Recovery Flags are used to indicate when LSP segment recovery
is desired. When these bits are set branch and merge nodes are
dynamically identified.
Note, the procedures defined in this section parallel the explicit
control procedures defined above in Section 4.2. The primary
difference is in creation of a recovery LSP's ERO.
6.1. Modified Protection Object Format
LSP Segment Recovery Flags are carried in the Protection object C-
Type defined in [E2E-RECOVERY]. The format of the flags are:
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(37) | C-Type (TBA) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|S|P|N|O| Reserved | LSP Flags | Reserved | Link Flags|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|I| Reserved | Seg.Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
In-Place (I): 1 bit
When set (1) indicates that the desired segment recovery type
indicated in the LSP Segment Recovery Flag is already in place
for the associated LSP.
(LSP) Segment (Recovery) Flags: 6 bits
This field is used to indicate when an upstream node desires
LSP Segment recovery to be dynamically initiated where
possible. The values used in this field are identical to the
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values defined for LSP Flags, see [E2E-RECOVERY].
See [E2E-RECOVERY] for the definition of other fields.
6.2. Dynamic Control Procedures
LSP Segment Recovery Flags are set to indicate that LSP segment
recovery is desired for the LSP being signaled. The type of recovery
desired is indicated by the flags. The decision to set the LSP
Segment Recovery Flags is a local matter and outside the scope of
this document. A value of zero (0) means that no dynamic
identification of segment recovery branch nodes are needed for the
associated LSP. When the In-Place bit is set, it means that the
desired type of recovery is already in place for that particular LSP.
A transit node receiving a Path message containing a Protection
object with a non-zero LSP Segment Recovery Flags value and the In-
Place bit clear (0) SHOULD consider if it can support the indicated
recovery type and if it can identify an appropriate merge node for a
recovery LSP. Dynamic identification MUST NOT be done when the
processing node is identified as a branch node in an SERO. If a node
is unable to provide the indicated recovery type or identify a merge
node, the Path message MUST be processed normally and the LSP Segment
Recovery Flags MUST NOT be modified.
When a node dynamically identifies itself as a branch node and
identifies the merge node for the type of recovery indicated in the
LSP Segment Recovery Flags, it attempts to setup a recovery LSP. The
dynamically identified information, together with the Path message of
LSP being recovered provides the information to create the recovery
LSP.
The Path message for the recovery LSP is created at the branch node
by cloning the objects carried in the incoming Path message of the
LSP being protected. Certain objects are replaced or modified in the
recovery LSP's outgoing Path message. The Sender_template MUST be
updated to use an address on the local node, and the LSP ID MUST be
updated to ensure uniqueness. The Session object MUST be updated to
use the address of the dynamically identified merge node as the
tunnel endpoint, the tunnel ID MAY be updated, and the extended
tunnel ID MUST be set to the local node. The Protection object is
updated with the In-Place bit set (1). Any RROs and EROs present in
the incoming Path message MUST NOT be included in the recovery LSP. A
new ERO MAY be created based on any path information dynamically
computed by the local node.
The resulting Path message is used to create the recovery LSP. While
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the recovery LSP exists, the Protection object in the original Path
message MUST also be updated with the In-Place bit set (1). From
this point on, Standard Path message processing is used in processing
the resulting and original Path messages.
The merge node of a dynamically controlled recovery LSP SHOULD reset
(0) the In-Place bit in the Protection object of the outgoing Path
message associated with the terminated recovery LSP.
Unlike with explicit control, if the creation of a dynamically
identified recovery LSP fails for any reason, the recovery LSP is
removed and no error message or indication is sent upstream. With
this exception, all the other procedures for explicitly controlled
recovery LSPs apply to dynamically controlled recovery LSPs. These
other procedures are defined above in defined in Sections 4.2.1
through 4.2.4.
7. Additional Fast Reroute Considerations
This section is under construction.
8. Updated RSVP Message Formats
This section presents the RSVP message related formats as modified by
this document. Where they differ, formats for unidirectional LSPs
are presented separately from bidirectional LSPs.
The format of a Path message is as follows:
<Path Message> ::= <Common Header> [ <INTEGRITY> ]
[ [<MESSAGE_ID_ACK> | <MESSAGE_ID_NACK>] ... ]
[ <MESSAGE_ID> ]
<SESSION> <RSVP_HOP>
<TIME_VALUES>
[ <EXPLICIT_ROUTE> ]
<LABEL_REQUEST>
[ <PROTECTION> ]
[ <LABEL_SET> ... ]
[ <SESSION_ATTRIBUTE> ]
[ <NOTIFY_REQUEST> ... ]
[ <ADMIN_STATUS> ]
[ <ASSOCIATION> ... ]
[ <SECONDARY_EXPLICIT_ROUTE> ... ]
[ <POLICY_DATA> ... ]
<sender descriptor>
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The format of the sender description for unidirectional LSPs is:
<sender descriptor> ::= <SENDER_TEMPLATE> <SENDER_TSPEC>
[ <ADSPEC> ]
[ <RECORD_ROUTE> ]
[ <SUGGESTED_LABEL> ]
[ <RECOVERY_LABEL> ]
[ <SECONDARY_RECORD_ROUTE> ... ]
The format of the sender description for bidirectional LSPs is:
<sender descriptor> ::= <SENDER_TEMPLATE> <SENDER_TSPEC>
[ <ADSPEC> ]
[ <RECORD_ROUTE> ]
[ <SUGGESTED_LABEL> ]
[ <RECOVERY_LABEL> ]
<UPSTREAM_LABEL>
[ <SECONDARY_RECORD_ROUTE> ... ]
The format of a PathErr message is as follows:
<PathErr Message> ::= <Common Header> [ <INTEGRITY> ]
[ [<MESSAGE_ID_ACK> | <MESSAGE_ID_NACK>] ... ]
[ <MESSAGE_ID> ]
<SESSION> <ERROR_SPEC>
[ <ACCEPTABLE_LABEL_SET> ... ]
[ <SECONDARY_EXPLICIT_ROUTE> ... ]
[ <POLICY_DATA> ... ]
<sender descriptor>
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The format of a Resv message is as follows:
<Resv Message> ::= <Common Header> [ <INTEGRITY> ]
[ [<MESSAGE_ID_ACK> | <MESSAGE_ID_NACK>] ... ]
[ <MESSAGE_ID> ]
<SESSION> <RSVP_HOP>
<TIME_VALUES>
[ <RESV_CONFIRM> ] [ <SCOPE> ]
[ <NOTIFY_REQUEST> ... ]
[ <ADMIN_STATUS> ]
[ <POLICY_DATA> ... ]
<STYLE> <flow descriptor list>
<flow descriptor list> ::= <FF flow descriptor list>
| <SE flow descriptor>
<FF flow descriptor list> ::= <FLOWSPEC> <FILTER_SPEC>
<LABEL> [ <RECORD_ROUTE> ]
[ <SECONDARY_RECORD_ROUTE> ... ]
| <FF flow descriptor list>
<FF flow descriptor>
<FF flow descriptor> ::= [ <FLOWSPEC> ] <FILTER_SPEC> <LABEL>
[ <RECORD_ROUTE> ]
[ <SECONDARY_RECORD_ROUTE> ... ]
<SE flow descriptor> ::= <FLOWSPEC> <SE filter spec list>
<SE filter spec list> ::= <SE filter spec>
| <SE filter spec list> <SE filter spec>
<SE filter spec> ::= <FILTER_SPEC> <LABEL> [ <RECORD_ROUTE> ]
[ <SECONDARY_RECORD_ROUTE> ... ]
9. Security Considerations
This document introduces no additional security considerations. See
[RFC3473] for relevant security considerations.
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10. IANA Considerations
This document requests assignment of a new Association Type within
the Association object. It also defines bits previously reserved in
the Protection object. Both of these objects were defined in [E2E-
RECOVERY].
This document also defines the Secondary Explicit Route Objects and
Secondary Record Route Objects. Both of these objects of the form
11bbbbbb. The values 198 and 199 respectively are suggested. The c-
type values and sub-objects associated with the Secondary Explicit
Route Object should read "Same values as and sub-objects as
EXPLICIT_ROUTE (C-Num 20)." The c-type values and sub-objects
associated with the Secondary Record Route Object should read "Same
values as and sub-objects as RECORD_ROUTE (C-Num 21)."
11. Intellectual Property Considerations
This section is taken from Section 10.4 of [RFC2026].
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain a general license or permission for the use of such
proprietary rights by implementors or users of this specification can
be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.
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12. References
12.1. Normative References
[RFC3209] Awduche, et al, "RSVP-TE: Extensions to RSVP for
LSP Tunnels", RFC 3209, December 2001.
[RFC3471] Berger, L., Editor, "Generalized Multi-Protocol
Label Switching (GMPLS) Signaling Functional
Description", RFC 3471, January 2003.
[RFC3473] Berger, L., Editor, "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling - Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions",
RFC 3473, January 2003.
[E2E-RECOVERY] Lang, J.P., Rekhter, Y., Papadimitriou, D., Editors,
"RSVP-TE Extensions in support of End-to-End
GMPLS-based Recovery", Work in Progress,
draft-lang-ccamp-gmpls-recovery-e2e-signaling-03.txt,
February 2004.
[FRR] Pan, et al, "Fast Reroute Extensions to RSVP-TE for LSP
Tunnels", draft-ietf-mpls-rsvp-lsp-fastreroute-03.txt,
December 2003.
12.2. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels," RFC 2119.
[FUNCT] J.P.Lang and B.Rajagopalan (Editors), "Generalized MPLS
Recovery Functional Specification," Internet Draft,
Work in Progress, draft-ietf-ccamp-gmpls-recovery-
functional-01.txt, September 2003.
[TERM] E.Mannie and D.Papadimitriou (Editors), "Recovery
(Protection and Restoration) Terminology for GMPLS,"
Internet Draft, Work in progress, draft-ietf-ccamp-
gmpls-recovery-terminology-02.txt, May 2003.
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13. Contributors
Lou Berger
Movaz Networks, Inc.
7926 Jones Branch Drive
Suite 615
McLean VA, 22102
Phone: +1 703 847-1801
Email: lberger@movaz.com
Igor Bryskin
Movaz Networks, Inc.
7926 Jones Branch Drive
Suite 615
McLean VA, 22102
Email: ibryskin@movaz.com
Adrian Farrel
Old Dog Consulting
Phone: +44 (0) 1978 860944
Email: adrian@olddog.co.uk
Dimitri Papadimitriou (Alcatel)
Francis Wellesplein 1
B-2018 Antwerpen, Belgium
Phone: +32 3 240-8491
Email: dimitri.papadimitriou@alcatel.be
14. Full Copyright Statement
Copyright (C) The Internet Society (2004). All Rights Reserved. This
document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
Berger, et al. [Page 22]
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The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. This
document and the information contained herein is provided on an "AS
IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK
FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL
NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY
OR FITNESS FOR A PARTICULAR PURPOSE.
Berger, et al. [Page 23]
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