draft-ietf-ccamp-rsvp-te-exclude-route-02.txt   draft-ietf-ccamp-rsvp-te-exclude-route-03.txt 
CCAMP Working Group CY Lee
Internet Draft A. Farrel Network Working Group CY. Lee
Expiration Date: January 2005 S. De Cnodder Internet-Draft Alcatel
July 2004 Expires: August 22, 2005 A. Farrel
Old Dog Consulting
S. De Cnodder
Alcatel
February 18, 2005
Exclude Routes - Extension to RSVP-TE Exclude Routes - Extension to RSVP-TE
<draft-ietf-ccamp-rsvp-te-exclude-route-02.txt> draft-ietf-ccamp-rsvp-te-exclude-route-03.txt
1. Status of this memo Status of this Memo
By submitting this Internet-Draft, I certify that any applicable This document is an Internet-Draft and is subject to all provisions
patent or other IPR claims of which I am aware have been disclosed, of Section 3 of RFC 3667. By submitting this Internet-Draft, each
or will be disclosed, and any of which I become aware will be author represents that any applicable patent or other IPR claims of
disclosed, in accordance with RFC 3668. which he or she is aware have been or will be disclosed, and any of
which he or she become aware will be disclosed, in accordance with
RFC 3668.
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2. Abstract This Internet-Draft will expire on August 22, 2005.
Copyright Notice
Copyright (C) The Internet Society (2005).
Abstract
The current RSVP-TE specification, "RSVP-TE: Extensions to RSVP for The current RSVP-TE specification, "RSVP-TE: Extensions to RSVP for
LSP Tunnels" (RFC 3209) and GMPLS extensions to RSVP-TE, "Generalized LSP Tunnels" (RFC 3209) and GMPLS extensions to RSVP-TE, "Generalized
Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions" (RFC 3473) allow Protocol-Traffic Engineering (RSVP-TE) Extensions" (RFC 3473) allow
abstract nodes and resources to be explicitly included in a path abstract nodes and resources to be explicitly included in a path
setup, but not to be explicitly excluded. setup, but not to be explicitly excluded.
In some networks where precise explicit paths are not computed at the In some networks where precise explicit paths are not computed at the
head end it may be useful to specify and signal abstract nodes and head end it may be useful to specify and signal abstract nodes and
resources that are to be explicitly excluded from routes. These resources that are to be explicitly excluded from routes. These
exclusions may apply to the whole path, or to parts of a path between exclusions may apply to the whole path, or to parts of a path between
two abstract nodes specified in an explicit path. How Shared Risk two abstract nodes specified in an explicit path. How Shared Risk
Link Groups (SLRGs) can be excluded is also specified in this Link Groups (SLRGs) can be excluded is also specified in this
document. document.
This document specifies ways to communicate route exclusions during This document specifies ways to communicate route exclusions during
path setup using RSVP-TE. path setup using RSVP-TE.
2.1 Changes compared to version 01 Table of Contents
References updated.
- Editorial updates.
- Added Unnumbered Interface exclusions
- Acknowledgements updated.
- IPR section.
- Appendix A with applications is added. 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 4
1.1 Changes compared to version 01 . . . . . . . . . . . . . . 4
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Scope of Exclude Routes . . . . . . . . . . . . . . . . . 5
2.2 Relationship to MPLS TE MIB . . . . . . . . . . . . . . . 7
3. Shared Risk Link Groups . . . . . . . . . . . . . . . . . . . 8
3.1 SRLG ERO Subobject . . . . . . . . . . . . . . . . . . . . 8
4. Exclude Route List . . . . . . . . . . . . . . . . . . . . . . 9
4.1 Exclude Route Object (XRO) . . . . . . . . . . . . . . . . 9
4.1.1 Subobject 1: IPv4 prefix . . . . . . . . . . . . . . 10
4.1.2 Subobject 2: IPv6 Prefix . . . . . . . . . . . . . . 11
4.1.3 Subobject 32: Autonomous System Number . . . . . . . 11
4.1.4 Subobject TBD: SRLG . . . . . . . . . . . . . . . . . 12
4.1.5 Subobject 4: Unnumbered Interface ID Subobject . . . . 12
4.2 Semantics and Processing Rules for the Exclude Route
Object (XRO) . . . . . . . . . . . . . . . . . . . . . . . 13
5. Explicit Exclude Route . . . . . . . . . . . . . . . . . . . . 16
5.1 Explicit Exclusion Route Subobject (EXRS) . . . . . . . . 16
5.2 Semantics and Processing Rules for the EXRS . . . . . . . 17
6. Minimum compliance . . . . . . . . . . . . . . . . . . . . . . 18
7. Security Considerations . . . . . . . . . . . . . . . . . . . 19
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
8.1 New Class Numbers . . . . . . . . . . . . . . . . . . . . 20
8.2 New Subobject Types . . . . . . . . . . . . . . . . . . . 20
8.3 New Error Codes . . . . . . . . . . . . . . . . . . . . . 20
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 22
10.1 Normative References . . . . . . . . . . . . . . . . . . . 22
10.2 Informational References . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 23
A. applications . . . . . . . . . . . . . . . . . . . . . . . . . 24
A.1 Inter-area LSP protection . . . . . . . . . . . . . . . . 24
A.2 Inter-AS LSP protection . . . . . . . . . . . . . . . . . 25
A.3 Protection in the GMPLS overlay model . . . . . . . . . . 26
A.4 LSP protection inside a single area . . . . . . . . . . . 28
Intellectual Property and Copyright Statements . . . . . . . . 29
3. Conventions used in this document 1. Requirements notation
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 [RFC2119]. document are to be interpreted as described in [RFC2119].
4. Overview 1.1 Changes compared to version 01
The current RSVP-TE specification [RSVP-TE] and GMPLS extensions o References updated.
[GMPLS-RSVP-TE] allow abstract nodes and resources to be explicitly o Editorial updates.
o Added Unnumbered Interface exclusions
o Acknowledgements updated.
o IPR section.
o Appendix A with applications is added.
2. Introduction
The current RSVP-TE specification [RFC3209] and GMPLS extensions
[RFC3473] allow abstract nodes and resources to be explicitly
included in a path setup, using the Explicit Route Object (ERO). included in a path setup, using the Explicit Route Object (ERO).
In some systems it may be useful to specify and signal abstract nodes In some systems it may be useful to specify and signal abstract nodes
and resources that are to be explicitly excluded from routes. This and resources that are to be explicitly excluded from routes. This
may be because loose hops or abstract nodes need to be prevented from may be because loose hops or abstract nodes need to be prevented from
selecting a route through a specific resource. This is a special case selecting a route through a specific resource. This is a special
of distributed path calculation in the network. case of distributed path calculation in the network.
Two types of exclusions are required: Two types of exclusions are required:
i) Exclude any of the abstract nodes in a given set anywhere on the 1. Exclude any of the abstract nodes in a given set anywhere on the
path. This set of abstract nodes is referred to as the Exclude path. This set of abstract nodes is referred to as the Exclude
Route list. Route list.
2. Exclude certain abstract nodes or resources between a specific
ii) Exclude certain abstract nodes or resources between a specific pair of abstract nodes present in an ERO. Such specific
pair of abstract nodes present in an ERO. Such specific exclu- exclusions are referred to as Explicit Exclusion Route.
sions are referred to as Explicit Exclusion Route.
To convey these constructs within the signaling protocol, a new RSVP To convey these constructs within the signaling protocol, a new RSVP
object and a new ERO subobject are introcuded respectively. object and a new ERO subobject are introcuded respectively.
i) A new RSVP-TE object is introduced to convey the Exclude Route 1. A new RSVP-TE object is introduced to convey the Exclude Route
list. This object is the Exclude Route Object (XRO). list. This object is the Exclude Route Object (XRO).
2. The second type of exclusion is achieved through a modification
ii) The second type of exclusion is achieved through a modification
to the existing ERO. A new subobject type the Explicit Exclude to the existing ERO. A new subobject type the Explicit Exclude
Route Subobject (EXRS) is introduced to indicate an exclusion Route Subobject (EXRS) is introduced to indicate an exclusion
between a pair of included abstract nodes. between a pair of included abstract nodes.
The knowledge of SRLGs, as defined in [INTERAS-REQ], may be used to The knowledge of SRLGs, as defined in [INTERAS-REQ], may be used to
compute diverse paths that can be used for protection. In systems compute diverse paths that can be used for protection. In systems
where it is useful to signal exclusions, it may be useful to signal where it is useful to signal exclusions, it may be useful to signal
SRLGs to indicate groups of resources that should be excluded on the SRLGs to indicate groups of resources that should be excluded on the
whole of a path or between two abstract nodes specified in an expli- whole of a path or between two abstract nodes specified in an
cit path. explicit path.
This document introduces an ERO subobject to indicate an SRLG to be This document introduces an ERO subobject to indicate an SRLG to be
signaled in either of the two exclusion methods described above. This signaled in either of the two exclusion methods described above.
subobject might also be appropriate for use within Explicit Routes or This subobject might also be appropriate for use within Explicit
Record Routes, but that discussion is outside the scope of this docu- Routes or Record Routes, but that discussion is outside the scope of
ment. this document.
4.1 Scope of Exclude Routes 2.1 Scope of Exclude Routes
This document does not preclude a route exclusion from listing many This document does not preclude a route exclusion from listing many
nodes or network elements to avoid. The intent is, however, to indi- nodes or network elements to avoid. The intent is, however, to
cate only the minimal number of subobjects to be avoided. For indicate only the minimal number of subobjects to be avoided. For
instance it may be necessary to signal only the SRLGs (or Shared instance it may be necessary to signal only the SRLGs (or Shared
Risk Groups) to avoid. Risk Groups) to avoid.
It is envisaged that most of the conventional inclusion subobjects It is envisaged that most of the conventional inclusion subobjects
are specified in the signaled ERO only for the area where they are are specified in the signaled ERO only for the area where they are
pertinent. The number of subobjects to be avoided, specified in the pertinent. The number of subobjects to be avoided, specified in the
signaled XRO may be constant throughout the whole path setup, or the signaled XRO may be constant throughout the whole path setup, or the
subobjects to be avoided may be removed from the XRO as they become subobjects to be avoided may be removed from the XRO as they become
irrelevant in the subsequent hops of the path setup. irrelevant in the subsequent hops of the path setup.
For example, consider an LSP that traverses multiple computation For example, consider an LSP that traverses multiple computation
domains. A computation domain may be an area in the administrative domains. A computation domain may be an area in the administrative
or IGP sense, or may be an arbitrary division of the network for or IGP sense, or may be an arbitrary division of the network for
active management and path computational purposes. Let the primary active management and path computational purposes. Let the primary
path be (Ingress, A1, A2, AB1, B1, B2, BC1, C1, C2, Egress) where: path be (Ingress, A1, A2, AB1, B1, B2, BC1, C1, C2, Egress) where:
o Xn denotes a node in domain X, and
- Xn denotes a node in domain X, and o XYn denotes a node on the border of domain X and domain Y.
- XYn denotes a node on the border of domain X and domain Y.
Note that Ingress is a node in domain A, and Egress is a node in Note that Ingress is a node in domain A, and Egress is a node in
domain C. This is shown in Figure 1 where the domains correspond with domain C. This is shown in Figure 1 where the domains correspond
areas. with areas.
area A area B area C area A area B area C
<-------------------> <----------------> <------------------> <-------------------> <----------------> <------------------>
Ingress-----A1----A2----AB1----B1----B2----BC1----C1----C2----Egress Ingress-----A1----A2----AB1----B1----B2----BC1----C1----C2----Egress
^ \ / | \ / | \ / ^ \ / | \ / | \ /
| \ / | \ / | \ / | \ / | \ / | \ /
| A3----------A4--AB2--B3--------B4--BC2--C3----------C4 | A3----------A4--AB2--B3--------B4--BC2--C3----------C4
| ^ ^ | ^ ^
| | | | | |
| | ERO: (C3-strict, C4-strict, | | ERO: (C3-strict, C4-strict,
| | Egress-strict) | | Egress-strict)
| | XRO: Not needed | | XRO: Not needed
| | | |
skipping to change at page 4, line 33 skipping to change at page 6, line 46
| | Egress-strict) | | Egress-strict)
| | XRO: Not needed | | XRO: Not needed
| | | |
| ERO: (B3-strict, B4-strict, BC2-strict, Egress-loose) | ERO: (B3-strict, B4-strict, BC2-strict, Egress-loose)
| XRO: (C1, C2) | XRO: (C1, C2)
| |
ERO: (A3-strict, A4-strict, AB2-strict, Egress-loose) ERO: (A3-strict, A4-strict, AB2-strict, Egress-loose)
XRO: (B1, B2, BC1, C1, C2, Egress) XRO: (B1, B2, BC1, C1, C2, Egress)
Consider the establishment of a node-diverse protection path in the Consider the establishment of a node-diverse protection path in the
example above. The protection path must avoid all nodes on the pri- example above. The protection path must avoid all nodes on the
mary path. The exclusions for area A are handled during Constrained primary path. The exclusions for area A are handled during
Shortest Path First (CSPF) computation at Ingress, so the ERO and XRO Constrained Shortest Path First (CSPF) computation at Ingress, so the
signaled at Ingress could be (A3-strict, A4-strict, AB2-strict, ERO and XRO signaled at Ingress could be (A3-strict, A4-strict,
Egress-loose) and (B1, B2, BC1, C1, C2) respectively. At AB2 the ERO AB2-strict, Egress-loose) and (B1, B2, BC1, C1, C2) respectively. At
and XRO could be (B3-strict, B4-strict, BC2-strict, Egress-loose) and AB2 the ERO and XRO could be (B3-strict, B4-strict, BC2-strict,
(C1,C2) respectively. At BC2 the ERO could be (C3-strict, C4-strict, Egress-loose) and (C1,C2) respectively. At BC2 the ERO could be
Egress-strict) and an XRO is not needed from BC2 onwards. (C3-strict, C4-strict, Egress-strict) and an XRO is not needed from
BC2 onwards.
In general, consideration should be given (as with explicit route) to In general, consideration should be given (as with explicit route) to
the size of signaled data and the impact on the signaling protocol. the size of signaled data and the impact on the signaling protocol.
4.2 Relationship to MPLS TE MIB 2.2 Relationship to MPLS TE MIB
[MPLS-TE-MIB] defines managed objects for managing and modeling [RFC3812] defines managed objects for managing and modeling
MPLS-based traffic engineering. Included in [MPLS-TE-MIB] is a means MPLS-based traffic engineering. Included in [RFC3812] is a means to
to configure explicit routes for use on specific LSPs. This confi- configure explicit routes for use on specific LSPs. This
guration allows the exclusion of certain resources. configuration allows the exclusion of certain resources.
In systems where the full explicit path is not computed at the In systems where the full explicit path is not computed at the
ingress (or at a path computation site for use at the ingress) it may ingress (or at a path computation site for use at the ingress) it may
be necessary to signal those exclusions. This document offers a means be necessary to signal those exclusions. This document offers a
of doing this signaling. means of doing this signaling.
5. Shared Risk Link Groups 3. Shared Risk Link Groups
The identifier of a SRLG is defined as a 32 bit quantity in [GMPLS- The identifier of a SRLG is defined as a 32 bit quantity in [GMPLS-
OSPF]. OSPF].
5.1 SRLG ERO Subobject 3.1 SRLG ERO Subobject
The format of the ERO and its subobjects are defined in [RSVP-TE]. The format of the ERO and its subobjects are defined in [RFC3209].
The new SRLG subobject is defined by this document as follows. The new SRLG subobject is defined by this document as follows.
0 1 2 3 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 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 | SRLG Id (4 bytes) | |L| Type | Length | SRLG Id (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRLG Id (continued) | Reserved | | SRLG Id (continued) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L L
The L bit is an attribute of the subobject. The L bit is set The L bit is an attribute of the subobject. The L bit is set
if the subobject represents a loose hop in the explicit route. if the subobject represents a loose hop in the explicit route.
If the bit is not set, the subobject represents a strict hop in If the bit is not set, the subobject represents a strict hop in
the explicit route. the explicit route.
For exclusions (as used by XRO and EXRS defined in this docu- For exclusions (as used by XRO and EXRS defined in this
ment), the L bit SHOULD be set to zero and ignored. document), the L bit SHOULD be set to zero and ignored.
Type Type
The type of the subobject [TBD]. The type of the subobject [TBD].
Length Length
The Length contains the total length of the subobject in bytes, The Length contains the total length of the subobject in bytes,
including the Type and Length fields. The Length is always 8. including the Type and Length fields. The Length is always 8.
skipping to change at page 6, line 4 skipping to change at page 8, line 47
Length Length
The Length contains the total length of the subobject in bytes, The Length contains the total length of the subobject in bytes,
including the Type and Length fields. The Length is always 8. including the Type and Length fields. The Length is always 8.
SRLG Id SRLG Id
The 32 bit identifier of the SRLG. The 32 bit identifier of the SRLG.
Reserved Reserved
Zero on transmission. Ignored on receipt Zero on transmission. Ignored on receipt
6. Exclude Route List 4. Exclude Route List
The exclude route identifies a list of abstract nodes that MUST NOT The exclude route identifies a list of abstract nodes that MUST NOT
be traversed along the path of the LSP being established. It is be traversed along the path of the LSP being established. It is
RECOMMENDED to limit size of the exlude route list to a value local RECOMMENDED to limit size of the exlude route list to a value local
to the node originating the exclude route list. to the node originating the exclude route list.
6.1 Exclude Route Object (XRO) 4.1 Exclude Route Object (XRO)
Abstract nodes to be excluded from the path are specified via the Abstract nodes to be excluded from the path are specified via the
EXCLUDE_ROUTE object (XRO). The Exclude Route Class value is [TBD]. EXCLUDE_ROUTE object (XRO). The Exclude Route Class value is [TBD].
Currently one C_Type is defined, Type 1 Exclude Route. The Currently one C_Type is defined, Type 1 Exclude Route. The
EXCLUDE_ROUTE object has the following format: EXCLUDE_ROUTE object has the following format:
Class = TBD, C_Type = 1 Class = TBD, C_Type = 1
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// (Subobjects) // // (Subobjects) //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Subobjects Subobjects
The contents of an EXCLUDE_ROUTE object are a series of variable- The contents of an EXCLUDE_ROUTE object are a series of variable-
length data items called subobjects. The subobjects are identical length data items called subobjects. The subobjects are identical to
to those defined in [RSVP-TE] and [GMPLS-RSVP-TE] for use in EROs. those defined in [RFC3209] and [RFC3473] for use in EROs.
The following subobject types are supported. The following subobject types are supported.
Type Subobject Type Subobject
1 IPv4 prefix 1 IPv4 prefix
2 IPv6 prefix 2 IPv6 prefix
4 Unnumbered Interface ID 4 Unnumbered Interface ID
32 Autonomous system number 32 Autonomous system number
TBD SRLG TBD SRLG
The defined values for Type above are specified in [RSVP-TE] and The defined values for Type above are specified in [RFC3209] and in
in this document. this document.
The concept of loose or strict hops has no meaning in route exclu- The concept of loose or strict hops has no meaning in route
sion. The L bit, defined for ERO subobjects in [RSPV-TE], is re- exclusion. The L bit, defined for ERO subobjects in [RSPV-TE], is
used here to indicate that an abstract node MUST be avoided (value reused here to indicate that an abstract node MUST be avoided (value
0) or SHOULD be avoided (value 1). 0) or SHOULD be avoided (value 1).
An Attribute octet is introduced in the subobjects that define IP An Attribute octet is introduced in the subobjects that define IP
addresses to indicate the attribute (e.g. interface, node, SRLG) addresses to indicate the attribute (e.g. interface, node, SRLG)
associated with the IP addresses that can be excluded from the associated with the IP addresses that can be excluded from the path.
path. For instance, the attribute node allows a whole node to be For instance, the attribute node allows a whole node to be excluded
excluded from the path, in contrast to the attribute interface, from the path, in contrast to the attribute interface, which allows
which allows specific interfaces to be excluded from the path. specific interfaces to be excluded from the path. The attribute SRLG
The attribute SRLG allows all SRLGs associated with an IP address allows all SRLGs associated with an IP address to be excluded from
to be excluded from the path. the path.
6.1.1 Subobject 1: IPv4 prefix 4.1.1 Subobject 1: IPv4 prefix
0 1 2 3 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 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 | IPv4 address (4 bytes) | |L| Type | Length | IPv4 address (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 address (continued) | Prefix Length | Attribute | | IPv4 address (continued) | Prefix Length | Attribute |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L L
skipping to change at page 7, line 38 skipping to change at page 10, line 38
Attribute Attribute
interface interface
0 indicates that the interface or set of interfaces associ- 0 indicates that the interface or set of interfaces associ-
ated with the IP prefix should be excluded or avoided ated with the IP prefix should be excluded or avoided
node node
1 indicates that the node or set of nodes associated with the 1 indicates that the node or set of nodes associated with
IP prefix should be excluded or avoided the IP prefix should be excluded or avoided
SRLG SRLG
2 indicates that all the SRLGs associated with the IP prefix 2 indicates that all the SRLGs associated with the IP
should be excluded or avoided prefix should be excluded or avoided
The rest of the fields are as defined in [RSVP-TE]. The rest of the fields are as defined in [RFC3209].
4.1.2 Subobject 2: IPv6 Prefix
6.1.2 Subobject 2: IPv6 Prefix
0 1 2 3 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 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 | IPv6 address (16 bytes) | |L| Type | Length | IPv6 address (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 address (continued) | | IPv6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 address (continued) | | IPv6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 address (continued) | | IPv6 address (continued) |
skipping to change at page 8, line 31 skipping to change at page 11, line 35
Attribute Attribute
interface interface
0 indicates that the interface or set of interfaces associ- 0 indicates that the interface or set of interfaces associ-
ated with the IP prefix should be excluded or avoided ated with the IP prefix should be excluded or avoided
node node
1 indicates that the node or set of nodes associated with the 1 indicates that the node or set of nodes associated with
IP prefix should be excluded or avoided the IP prefix should be excluded or avoided
SRLG SRLG
2 indicates that all the SRLG associated with the IP prefix 2 indicates that all the SRLG associated with the IP
should be excluded or avoided prefix should be excluded or avoided
The rest of the fields are as defined in [RSVP-TE]. The rest of the fields are as defined in [RFC3209].
6.1.3 Subobject 32: Autonomous System Number 4.1.3 Subobject 32: Autonomous System Number
The L bit of an Autonomous System Number subobject has meaning in The L bit of an Autonomous System Number subobject has meaning in an
an Exclude Route (contrary to its usage in an Explict Route Exclude Route (contrary to its usage in an Explict Route defined in
defined in [RSVP-TE]. The meaning is as for other subobjects [RFC3209]. The meaning is as for other subobjects described above.
described above. That is: That is:
0 indicates that the abstract node specified MUST be excluded 0 indicates that the abstract node specified MUST be excluded
1 indicates that the abstract node specified SHOULD be avoided 1 indicates that the abstract node specified SHOULD be avoided
The rest of the fields are as defined in [RSVP-TE]. There is no
The rest of the fields are as defined in [RFC3209]. There is no
Attribute octet defined. Attribute octet defined.
6.1.4 Subobject TBD: SRLG 4.1.4 Subobject TBD: SRLG
The meaning of the L bit is as follows: The meaning of the L bit is as follows:
0 indicates that the SRLG specified MUST be excluded 0 indicates that the SRLG specified MUST be excluded
1 indicates that the SRLG specified SHOULD be avoided 1 indicates that the SRLG specified SHOULD be avoided
The Attribute octet is not present. The rest of the fields are as The Attribute octet is not present. The rest of the fields are as
defined in the "SRLG ERO Subobject" section of this document. defined in the "SRLG ERO Subobject" section of this document.
6.1.5 Subobject 4: Unnumbered Interface ID Subobject 4.1.5 Subobject 4: Unnumbered Interface ID Subobject
0 1 2 3 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 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 | Attribute | |L| Type | Length | Reserved | Attribute |
| | | |(must be zero) | | | | | |(must be zero) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router ID | | Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID (32 bits) | | Interface ID (32 bits) |
skipping to change at page 9, line 32 skipping to change at page 12, line 37
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved | Attribute | |L| Type | Length | Reserved | Attribute |
| | | |(must be zero) | | | | | |(must be zero) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Router ID | | Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID (32 bits) | | Interface ID (32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L L
0 indicates that the attribute specified MUST be excluded 0 indicates that the attribute specified MUST be excluded
1 indicates that the attribute specified SHOULD be avoided 1 indicates that the attribute specified SHOULD be avoided
Attribute Attribute
interface interface
0 indicates that the Interface ID specified should be excluded 0 indicates that the Interface ID specified should be
or avoided excluded or avoided
node node
1 indicates that the node with the Router ID should be 1 indicates that the node with the Router ID should be
excluded or avoided (this can be achieved using IPv4/v6 excluded or avoided (this can be achieved using IPv4/v6
subobject as well, but is included here because it may be subobject as well, but is included here because it may be
convenient to use subobjects from RRO, in specifying the convenient to use subobjects from RRO, in specifying the
exclusions) exclusions)
SRLG SRLG
2 indicates that all the SRLGs associated with the interface
should be excluded or avoided 2 indicates that all the SRLGs associated with the
interface should be excluded or avoided
Reserved Reserved
Zero on transmission. Ignored on receipt. Zero on transmission. Ignored on receipt.
The rest of the fields are as defined in [MPLS_UNNUM]. The rest of the fields are as defined in [RFC3477].
6.2. Semantics and Processing Rules for the Exclude Route Object (XRO) 4.2 Semantics and Processing Rules for the Exclude Route Object (XRO)
The exclude route list is encoded as a series of subobjects con- The exclude route list is encoded as a series of subobjects con-
tained in an EXCLUDE_ROUTE object. Each subobject identifies an tained in an EXCLUDE_ROUTE object. Each subobject identifies an
abstract node in the exclude route list. abstract node in the exclude route list.
Each abstract node may be a precisely specified IP address belong- Each abstract node may be a precisely specified IP address belonging
ing to a node, or an IP address with prefix identifying interfaces to a node, or an IP address with prefix identifying interfaces of a
of a group of nodes, or an Autonomous System. group of nodes, or an Autonomous System.
The Explicit Route and routing processing is unchanged from the The Explicit Route and routing processing is unchanged from the
description in [RSVP-TE] with the following additions: description in [RFC3209] with the following additions:
a. When a Path message is received at a node, the node must check 1. When a Path message is received at a node, the node must check
that it is not a member of any of the abstract nodes in the XRO if that it is not a member of any of the abstract nodes in the XRO
it is present in the Path message. If the node is a member of any if it is present in the Path message. If the node is a member of
of the abstract nodes in the XRO with the L-flag set to "exclude", any of the abstract nodes in the XRO with the L-flag set to
it should return a PathErr with the error code "Routing Problem" "exclude", it should return a PathErr with the error code
and error value of "Local node in Exclude Route". If there are "Routing Problem" and error value of "Local node in Exclude
SRLGs in the XRO, the node should check that the resources the Route". If there are SRLGs in the XRO, the node should check
node uses are not part of any SRLG with the L-flag set to that the resources the node uses are not part of any SRLG with
"exclude" that is specified in the XRO. If it is, it should the L-flag set to "exclude" that is specified in the XRO. If it
return a PathErr with error code "Routing Problem" and error value is, it should return a PathErr with error code "Routing Problem"
of "Local node in Exclude Route". and error value of "Local node in Exclude Route".
b. Each subobject must be consistent. If a subobject is not con- 2. Each subobject must be consistent. If a subobject is not con-
sistent then the node should return a PathErr with error code sistent then the node should return a PathErr with error code
"Routing Problem" and error value "Inconsistent Subobject". An "Routing Problem" and error value "Inconsistent Subobject". An
example of an inconsistent subobject is an IPv4 Prefix subobject example of an inconsistent subobject is an IPv4 Prefix subobject
containing the IP address of a node and the attribute field is set containing the IP address of a node and the attribute field is
to "interface" or "SRLG". set to "interface" or "SRLG".
c. The subobjects in the ERO and XRO SHOULD not contradict each 3. The subobjects in the ERO and XRO SHOULD not contradict each
other. If they do contradict, the subobjects with the L flag not other. If they do contradict, the subobjects with the L flag not
set, strict or MUST be excluded, respectively, in the ERO or XRO set, strict or MUST be excluded, respectively, in the ERO or XRO
MUST take precedence. If there is still a conflict, a PathErr MUST take precedence. If there is still a conflict, a PathErr
with error code "Routing Problem" and error value of "Route with error code "Routing Problem" and error value of "Route
blocked by Exclude Route" should be returned. blocked by Exclude Route" should be returned.
d. When choosing a next hop or expanding an explicit route to include 4. When choosing a next hop or expanding an explicit route to
additional subobjects, a node: include additional subobjects, a node:
i) must not introduce an explicit node or an abstract node that 1. must not introduce an explicit node or an abstract node that
equals or is a member of any abstract node that is specified equals or is a member of any abstract node that is specified
in the Exclude Route Object with the L-flag set to "exclude". in the Exclude Route Object with the L-flag set to "exclude".
The number of introduced exlicit nodes or abstract nodes with The number of introduced exlicit nodes or abstract nodes with
the L flag set to "avoid" should be minimised. the L flag set to "avoid" should be minimised.
ii) must not introduce links, nodes or resources identified by the 2. must not introduce links, nodes or resources identified by
SRLG Id specified in the SRLG subobjects(s). The number of the SRLG Id specified in the SRLG subobjects(s). The number
introduced SLRGs with the L flag set to "avoid" should be of introduced SLRGs with the L flag set to "avoid" should be
minimised. minimised.
If these rules preclude further forwarding of the Path message, If these rules preclude further forwarding of the Path message,
the node should return a PathErr with the error code "Routing the node should return a PathErr with the error code "Routing
Problem" and error value of "Route blocked by Exclude Route". Problem" and error value of "Route blocked by Exclude Route".
Note that the subobjects in the XRO is an unordered list of subob- Note that the subobjects in the XRO is an unordered list of
jects. subob- jects.
The XRO Class-Num is of the form 11bbbbbb so that nodes which do not The XRO Class-Num is of the form 11bbbbbb so that nodes which do not
support the XRO will forward it uninspected and will not apply the support the XRO will forward it uninspected and will not apply the
extensions to ERO processing described above. This makes the XRO a extensions to ERO processing described above. This makes the XRO a
'best effort' process. 'best effort' process.
This 'best-effort' approach is chosen to allow route exclusion to This 'best-effort' approach is chosen to allow route exclusion to
traverse parts of the network that are not capable of parsing or han- traverse parts of the network that are not capable of parsing or
dling the new function. Note that Record Route may be used to allow handling the new function. Note that Record Route may be used to
computing nodes to observe violations of route exclusion and attempt allow computing nodes to observe violations of route exclusion and
to re-route the LSP accordingly. attempt to re-route the LSP accordingly.
If a node supports the XRO, but not a particular subobject or part of If a node supports the XRO, but not a particular subobject or part of
that subobject, then that particular subobject is ignored. Examples that subobject, then that particular subobject is ignored. Examples
of a part of a subobject that can be supported are: (1) only prefix of a part of a subobject that can be supported are: (1) only prefix
32 of the IPv4 prefix subobject could be supported, or (2) a particu- 32 of the IPv4 prefix subobject could be supported, or (2) a
lar subobject is supported but not the particular attribute field. particular subobject is supported but not the particular attribute
field.
When a node forwards a Path message, it can do the following three When a node forwards a Path message, it can do the following three
operations related to XRO besides of the processing rules mentioned operations related to XRO besides of the processing rules mentioned
above: above:
1. If no XRO was present, an XRO may be included. 1. If no XRO was present, an XRO may be included.
2. If an XRO was present, it may remove the XRO if it is sure that 2. If an XRO was present, it may remove the XRO if it is sure that
the next nodes do not need this information anymore. An example is the next nodes do not need this information anymore. An example
where a node can expand the ERO to a full strict path towards the is where a node can expand the ERO to a full strict path towards
destination. See Figure 1 where BC2 is removing the XRO from the the destination. See Figure 1 where BC2 is removing the XRO from
Path message. the Path message.
3. If an XRO was present, the content of the XRO can be modified. 3. If an XRO was present, the content of the XRO can be modified.
Subobjects can be added or removed. See Figure 1 for an example Subobjects can be added or removed. See Figure 1 for an example
where AB2 is stripping off some subobjects. where AB2 is stripping off some subobjects.
7. Explicit Exclude Route 5. Explicit Exclude Route
The Explicit Exclude Route defines abstract nodes or resources (such The Explicit Exclude Route defines abstract nodes or resources (such
as links, unnumbered interfaces or labels) that must not be used on as links, unnumbered interfaces or labels) that must not be used on
the path between two inclusive abstract nodes or resources in the the path between two inclusive abstract nodes or resources in the
explicit route. explicit route.
7.1. Explicit Exclusion Route Subobject (EXRS) 5.1 Explicit Exclusion Route Subobject (EXRS)
A new ERO subobject type is defined. The Explicit Exclude Route A new ERO subobject type is defined. The Explicit Exclude Route
Subobject (EXRS) has type [TBD]. The EXRS may not be present in an Subobject (EXRS) has type [TBD]. The EXRS may not be present in an
RRO or XRO. RRO or XRO.
The format of the EXRS is as follows. The format of the EXRS is as follows.
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------------//---------------+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------------//---------------+
|L| Type | Length | EXRS subobjects | |L| Type | Length | EXRS subobjects |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------------//---------------+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------------//---------------+
L L
ignored and must be zero
[Note: The L bit in an EXRS subobject is as defined for the XRO ignored and must be zero [Note: The L bit in an EXRS subobject
subobjects] is as defined for the XRO subobjects]
Type Type
The type of the subobject, i.e. EXRS [TBD] The type of the subobject, i.e. EXRS [TBD]
EXRS subobjects EXRS subobjects
An EXRS subobject indicates the abstract node or resource to be An EXRS subobject indicates the abstract node or resource to be
excluded. The format of this field is exactly the format of an excluded. The format of this field is exactly the format of an
XRO subobject and may include an SRLG subobject. Both subob- XRO subobject and may include an SRLG subobject. Both subob-
jects are as described earlier in this document. jects are as described earlier in this document.
Thus, an EXRO subobject for an IP hop might look as follows: Thus, an EXRO subobject for an IP hop might look as follows:
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 13, line 14 skipping to change at page 17, line 4
0 1 2 3 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 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 |L| Type | Length | |L| Type | Length |L| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 address (4 bytes) | | IPv4 address (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | Attribute | Reserved | | Prefix Length | Attribute | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: The Most Significant Bit in the Type field could be used to Note: The Most Significant Bit in the Type field could be used to
indicate exclusion of IPv4/IPv6, AS and SRLG subobjects, eliminating indicate exclusion of IPv4/IPv6, AS and SRLG subobjects, eliminating
the need to prepend the subobject with an additional TLV header. This the need to prepend the subobject with an additional TLV header.
would reduce the number bytes require for each subobject by 2 bytes. This would reduce the number bytes require for each subobject by 2
However, this approach would reduce the ERO Type field space by half. bytes. However, this approach would reduce the ERO Type field space
This issue need WG discussion and feedback. by half. This issue need WG discussion and feedback.
7.2. Semantics and Processing Rules for the EXRS 5.2 Semantics and Processing Rules for the EXRS
Each EXRS may carry multiple exclusions. The exclusion is encoded Each EXRS may carry multiple exclusions. The exclusion is encoded
exactly as for XRO subobjects and prefixed by an additional Type and exactly as for XRO subobjects and prefixed by an additional Type and
Length. Length.
The scope of the exclusion is the step between the previous ERO The scope of the exclusion is the step between the previous ERO
subobject that identifies an abstract node, and the subsequent ERO subobject that identifies an abstract node, and the subsequent ERO
subobject that identifies an abstract node. Multiple exclusions may subobject that identifies an abstract node. Multiple exclusions may
be present between any pair of abstract nodes. be present between any pair of abstract nodes.
Exclusions may indicate explicit nodes, abstract nodes or Autonomous Exclusions may indicate explicit nodes, abstract nodes or Autonomous
Systems that must not be traversed on the path to the next abstract Systems that must not be traversed on the path to the next abstract
node indicated in the ERO. node indicated in the ERO.
Exclusions may also indicate resources (such as unnumbered inter- Exclusions may also indicate resources (such as unnumbered
faces, link ids, labels) that must not be used on the path to the interfaces, link ids, labels) that must not be used on the path to
next abstract node indicated in the ERO. the next abstract node indicated in the ERO.
SRLGs may also be indicated for exclusion from the path to the next SRLGs may also be indicated for exclusion from the path to the next
abstract node in the ERO by the inclusion of an EXRO Subobject con- abstract node in the ERO by the inclusion of an EXRO Subobject
taining an SRLG subobject. If the L-bit value in the SRLG subobject containing an SRLG subobject. If the L-bit value in the SRLG
is zero, the resources (nodes, links, etc.) identified by the SRLG subobject is zero, the resources (nodes, links, etc.) identified by
MUST not be used on the path to the next abstract node indicated in the SRLG MUST not be used on the path to the next abstract node
the ERO. If the L-bit is set, the resources identified by the SRLG indicated in the ERO. If the L-bit is set, the resources identified
SHOULD be avoided. by the SRLG SHOULD be avoided.
The subobjects in the ERO and EXRS SHOULD not contradict each other. The subobjects in the ERO and EXRS SHOULD not contradict each other.
If they do contradict, the subobjects with the L bit not set, strict If they do contradict, the subobjects with the L bit not set, strict
or MUST be excluded, respectively, in the ERO or XRO MUST take pre- or MUST be excluded, respectively, in the ERO or XRO MUST take pre-
cedence. If there is still a conflict, the subobjects in the ERO cedence. If there is still a conflict, the subobjects in the ERO
MUST take precedence. MUST take precedence.
If a node is called upon to process an EXRS and does not support han- If a node is called upon to process an EXRS and does not support
dling of exclusions it will return a PathErr with a "Bad handling of exclusions it will return a PathErr with a "Bad
EXPLICIT_ROUTE object" error. EXPLICIT_ROUTE object" error.
If the presence of EXRO Subobjects precludes further forwarding of If the presence of EXRO Subobjects precludes further forwarding of
the Path message, the node should return a PathErr with the error the Path message, the node should return a PathErr with the error
code "Routing Problem" and error value of "Route blocked by Exclude code "Routing Problem" and error value of "Route blocked by Exclude
Route". Route".
8. Minimum compliance 6. Minimum compliance
An implementation must be at least compliant with the following: An implementation must be at least compliant with the following:
A. The XRO MUST be supported with the following restrictions: 1. The XRO MUST be supported with the following restrictions:
* The IPv4 Prefix subobject MUST be supported with a prefix
A.1. The IPv4 Prefix subobject MUST be supported with a prefix length length of 32, and an attribute value of "interface" and
of 32, and an attribute value of "interface" and "node". Other "node". Other prefix values and attribute values MAY be
prefix values and attribute values MAY be supported. supported.
* The IPv6 Prefix subobject MUST be supported with a prefix
A.2. The IPv6 Prefix subobject MUST be supported with a prefix length length of 128, and an attriubute value of "interface" and
of 128, and an attriubute value of "interface" and "node". Other "node". Other prefix values and attribute values MAY be
prefix values and attribute values MAY be supported. supported.
B. The EXRS SHOULD be supported. If supported, the same restrictions 2. The EXRS SHOULD be supported. If supported, the same
as for the XRO apply. restrictions as for the XRO apply.
C. If XRO or EXRS are supported, the implementation MUST be compliant 3. If XRO or EXRS are supported, the implementation MUST be
with the processing rules of the supported, not supported, or par- compliant with the processing rules of the supported, not
tially supported subobjects as specified within this document. supported, or partially supported subobjects as specified within
this document.
9. Security Considerations 7. Security Considerations
The new exclude route object poses no security exposures over and The new exclude route object poses no security exposures over and
above [RSVP-TE] and [GMPLS-RSVP-TE]. Note that any security con- above [RFC3209] and [RFC3473]. Note that any security concerns that
cerns that exist with Explicit Routes should be considered with exist with Explicit Routes should be considered with regard to route
regard to route exclusions. exclusions.
10. IANA Considerations 8. IANA Considerations
It might be considered that a possible approach would be to assign It might be considered that a possible approach would be to assign
one of the bits of the ERO sub-object type field (perhaps the top one of the bits of the ERO sub-object type field (perhaps the top
bit) to identify that a sub-object is intended for inclusion bit) to identify that a sub-object is intended for inclusion rather
rather than exclusion. However, [RSVP-TE] states that the type than exclusion. However, [RFC3209] states that the type field (seven
field (seven bits) should be assigned as 0 - 63 through IETF con- bits) should be assigned as 0 - 63 through IETF consensus action, 64
sensus action, 64 - 95 as first come first served, and 96 - 127 - 95 as first come first served, and 96 - 127 are reserved for
are reserved for private use. It would not be acceptable to dis- private use. It would not be acceptable to disrupt existing
rupt existing implementations so the only option would be to split implementations so the only option would be to split the IETF
the IETF consensus range leaving only 32 sub-object types. It is consensus range leaving only 32 sub-object types. It is felt that
felt that that would be an unacceptably small number for future that would be an unacceptably small number for future expansion of
expansion of the protocol. the protocol.
10.1. New Class Numbers 8.1 New Class Numbers
One new class number is required. One new class number is required.
EXCLUDE_ROUTE EXCLUDE_ROUTE
Class-Num = 011bbbbb Class-Num = 011bbbbb
CType: 1 CType: 1
10.2. New Subobject Types 8.2 New Subobject Types
A new subobject type for the Exclude Route Object and Explicit A new subobject type for the Exclude Route Object and Explicit
Exclude Route Subobject is required. Exclude Route Subobject is required.
SRLG subobject SRLG subobject
A new subobject type for the ERO is required. A new subobject type for the ERO is required.
Explicit Exclude Route subobject Explicit Exclude Route subobject
10.3. New Error Codes 8.3 New Error Codes
New error values are needed for the error code 'Routing Problem'. New error values are needed for the error code 'Routing Problem'.
Unsupported Exclude Route Subobject Type [TBD] Unsupported Exclude Route Subobject Type [TBD]
Inconsistent Subobject [TBD] Inconsistent Subobject [TBD]
Local Node in Exclude Route [TBD] Local Node in Exclude Route [TBD]
Route Blocked by Exclude Route [TBD] Route Blocked by Exclude Route [TBD]
11. Acknowledgments 9. Acknowledgments
This document reuses text from [RSVP-TE] for the description of This document reuses text from [RFC3209] for the description of
EXCLUDE_ROUTE. EXCLUDE_ROUTE.
The authors would like to express their thanks to Lou Berger, Steffen The authors would like to express their thanks to Lou Berger, Steffen
Brockmann, Igor Bryskin, Dimitri Papadimitriou, Cristel Pelsser, and Brockmann, Igor Bryskin, Dimitri Papadimitriou, Cristel Pelsser, and
Richard Rabbat for their considered opinions on this draft. Also Richard Rabbat for their considered opinions on this draft. Also
thanks to Yakov Rekhter for reminding us about SRLGs! thanks to Yakov Rekhter for reminding us about SRLGs!
12. Intellectual Property Considerations 10. References
This following is taken from Section 10.4 of [RFC-2026].
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to per-
tain 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.
The IETF has been notified of intellectual property rights claimed in
regard to some or all of the specification contained in this docu-
ment. For more information consult the online list of claimed
rights.
13. References 10.1 Normative References
13.1 Normative References [GMPLS-OSPF]
Kompella, K. and Y. Rekhter, "OSPF Extensions in Support
of Generalized Multi-Protocol Label Switching",
draft-ietf-ccamp-ospf-gmpls-extensions-12.txt, work in
progress, October 2003.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997 Requirement Levels", BCP 14, RFC 2119, March 1997.
[RSVP-TE] Awduche, D., et al., "RSVP-TE: Extensions to RSVP
for LSP Tunnels", RFC 3209, December 2001.
[GMPLS-RSVP-TE] Berger, L., (Editor), "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions",
RFC 3473, January 2003.
[GMPLS-OSPF] K. Kompela, Y. Rekhter, (Editors) "OSPF Extensions [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.
in Support of Generalized MPLS", Internet Draft, and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
draft-ietf-ccamp-ospf-gmpls-extensions-12.txt, Tunnels", RFC 3209, December 2001.
October 2003 (work in progress).
[MPLS-UNNUM] Kompella, K., Rekhter, Y., "Signalling Unnumbered [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
Links in RSVP-TE", RFC 3477, January 2003. (GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
www.ietf.org/ internet-drafts/draft-ietf-mpls-bundle-04.txt [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
in Resource ReSerVation Protocol - Traffic Engineering
(RSVP-TE)", RFC 3477, January 2003.
13.2 Informational References 10.2 Informational References
[MPLS-BUNDLE] Kompella, K., Rekhter, Y., and Berger, L., [CRANKBACK]
"Link Bundling in MPLS Traffic Engineering", Farrel, A., Satyanarayana, A., Iwata, A., Ash, G. and S.
Internet Draft, draft-ietf-mpls-bundle-04.txt, Marshall-Unitt, "Crankback Signaling Extensions for MPLS
July 2002, (work in progress). Signaling", draft-ietf-ccamp-crankback-02.txt, work in
progress, July 2004.
[MPLS-TE-MIB] C. Srinivasan, et al., "Multiprotocol Label [INTERAS] De Cnodder, S. and C. Pelsser, "Protection for inter-AS
Switching (MPLS) Traffic Engineering Management MPLS tunnels",
Information Base", Internet Draft, draft-ietf-mpls- draft-decnodder-ccamp-interas-protection-00.txt, work in
te-mib-09.txt, November 2002 (work in progress). progress, July 2004.
[INTERAS-REQ] R. Zhang, JP Vasseur (Editors), "MPLS Inter-AS Traffic [INTERAS-REQ]
Engineering Requirements", Internet Draft, Zhang, R. and JP. Vasseur, "MPLS Inter-AS Traffic
draft-ietf-tewg-interas-mpls-te-req-03.txt, December Engineering requirements",
2003 (work in progress). draft-ietf-tewg-interas-mpls-te-req-09.txt, work in
progress, September 2004.
[INTERAS] De Cnodder, S., Pelsser, C., "Protection for [MPLS-BUNDLE]
inter-AS MPLS tunnels", Internet Draft, draft- Kompella, K., Rekhter, Y. and L. Berger, "Link Bundling in
decnodder-mpls-interas-protection-00.txt, February MPLS Traffic Engineering",
2003, (work in progress). draft-ietf-mpls-bundle-04.txt, work in progress, July
2002.
[OVERLAY] Swallow, G., Drake, J., Ishimatsu, H., Rekhter, Y., [OVERLAY] Swallow, G., Drake, J., Ishimatsu, H. and Y. Rekhter,
GMPLS RSVP Support for the Overlay Model", Internet "GMPLS UNI: RSVP Support for the Overlay Model",
Draft, draft-ccamp-gmpls-overlay-02.txt, October draft-ietf-ccamp-gmpls-overlay-04.txt, work in progress,
2003, (work in progress). April 2004.
[OSPF-TE] Katz, D., Yeung, D., and Kompella, K., "Traffic [RFC3630] Katz, D., Kompella, K. and D. Yeung, "Traffic Engineering
Engineering Extensions to OSPF version 2", RFC 3630, (TE) Extensions to OSPF Version 2", RFC 3630, September
September 2003. 2003.
[ISIS-TE] Smit, H., Li, T., "IS-IS extensions for Traffic [RFC3784] Smit, H. and T. Li, "Intermediate System to Intermediate
Engineering", Internet Draft, draft-ietf-isis- System (IS-IS) Extensions for Traffic Engineering (TE)",
traffic-05.txt, August 2003, (work in progress). RFC 3784, June 2004.
[CRANKBACK] Farrel, A., (Editor), "Crankback Routing Extensions [RFC3812] Srinivasan, C., Viswanathan, A. and T. Nadeau,
for MPLS Signaling", Internet Draft, draft-iwata-mpls- "Multiprotocol Label Switching (MPLS) Traffic Engineering
crankback-05.txt, March 2003, (work in progress). (TE) Management Information Base (MIB)", RFC 3812, June
2004.
14. Authors' Information Authors' Addresses
Cheng-Yin Lee Cheng-Yin Lee
Alcatel Alcatel
600 March Road. 600 March Road.
Ottawa, Ontario Ottawa, Ontario
Canada K2K 2E6 Canada K2K 2E6
EMail: Cheng-Yin.Lee@alcatel.com
Email: Cheng-Yin.Lee@alcatel.com
Adrian Farrel Adrian Farrel
Old Dog Consulting Old Dog Consulting
Phone: +44 (0) 1978 860944 Phone: +44 (0) 1978 860944
EMail: adrian@olddog.co.uk Email: adrian@olddog.co.uk
Stefaan De Cnodder Stefaan De Cnodder
Alcatel Alcatel
Francis Wellesplein 1 Francis Wellesplein 1
B-2018 Antwerp, Belgium B-2018 Antwerp
EMail: stefaan.de_cnodder@alcatel.be Belgium
Appendix A: applications Phone: +32 3 240 85 15
Email: stefaan.de_cnodder@alcatel.be
Appendix A. applications
This section describes some applications that can make use of the This section describes some applications that can make use of the
XRO. The intention is to show that the XRO is not an application XRO. The intention is to show that the XRO is not an application
specific object, but that it can be used for multiple purposes. In a specific object, but that it can be used for multiple purposes. In a
few examples, other solutions might be possible for that particular few examples, other solutions might be possible for that particular
case but the intention is to show that also a single object can be case but the intention is to show that also a single object can be
used for all the examples, hence making the XRO a rather generic used for all the examples, hence making the XRO a rather generic
object without having to define a solution and new objects for each object without having to define a solution and new objects for each
new application. new application.
A.1 Inter-area LSP protection A.1 Inter-area LSP protection
One method to establish an inter-area LSP is where the ingress router One method to establish an inter-area LSP is where the ingress router
selects an ABR, and then the ingress router computes a path towards selects an ABR, and then the ingress router computes a path towards
this selected ABR such that the configured constraints of the LSP are this selected ABR such that the configured constraints of the LSP are
fulfilled. In the example of figure A.1, an LSP has to be established fulfilled. In the example of figure A.1, an LSP has to be
from node A in area 1 to node C in area 2. If no loose hops are con- established from node A in area 1 to node C in area 2. If no loose
figured, then the computed ERO at A could looks as follows: (A1- hops are con- figured, then the computed ERO at A could looks as
strict, A2-strict, ABR1-strict, C-loose). When the Path message follows: (A1- strict, A2-strict, ABR1-strict, C-loose). When the
arrives at ABR1, then the ERO is (ABR1-strict, C-loose) and it can be Path message arrives at ABR1, then the ERO is (ABR1-strict, C-loose)
expanded by ABR1 to (B1-strict, ABR3-strict, C-loose). Similar, at and it can be expanded by ABR1 to (B1-strict, ABR3-strict, C-loose).
ABR3 the received ERO is (ABR3-strict, C-loose) and it can be Similar, at ABR3 the received ERO is (ABR3-strict, C-loose) and it
expanded to (C1-strict, C2-strict, C-strict). If also a backup LSP can be expanded to (C1-strict, C2-strict, C-strict). If also a
has to be established, then A takes another ABR (ABR2 in this case) backup LSP has to be established, then A takes another ABR (ABR2 in
and computes a path towards this ABR that fulfills the constraints of this case) and computes a path towards this ABR that fulfills the
the LSP and such that is disjoint from the path of the primary LSP. constraints of the LSP and such that is disjoint from the path of the
The ERO generated by A looks as follows for this example: (A3-strict, primary LSP. The ERO generated by A looks as follows for this
A4-strict, ABR2-strict, C-loose). example: (A3-strict, A4-strict, ABR2-strict, C-loose).
In order to let ABR2 expand the ERO, it also needs to know the path In order to let ABR2 expand the ERO, it also needs to know the path
of the primary LSP to expand the ERO such that it is disjoint from of the primary LSP to expand the ERO such that it is disjoint from
the path of the primary LSP. Therefore, A also includes an XRO that the path of the primary LSP. Therefore, A also includes an XRO that
at least contains (ABR1, B1, ABR3, C1, C2). Based on these con- at least contains (ABR1, B1, ABR3, C1, C2). Based on these con-
straints, ABR2 can expand the ERO such that it is disjoint from the straints, ABR2 can expand the ERO such that it is disjoint from the
primary LSP. In this example, the ERO computed by ABR2 would be (B2- primary LSP. In this example, the ERO computed by ABR2 would be (B2-
strict, ABR4-strict, C-loose), and the XRO generated by B contains at strict, ABR4-strict, C-loose), and the XRO generated by B contains at
least (ABR3, C1, C2). The latter information is needed to let ABR4 to least (ABR3, C1, C2). The latter information is needed to let ABR4
expand the ERO such that the path is disjoint from the primary LSP in to expand the ERO such that the path is disjoint from the primary LSP
area 2. in area 2.
Area 1 Area 0 Area 2 Area 1 Area 0 Area 2
<---------------><--------------><---------------> <---------------><--------------><--------------->
+---A1---A2----ABR1-----B1-----ABR3----C1---C2---+ +---A1---A2----ABR1-----B1-----ABR3----C1---C2---+
| | | | | | | | | |
| | | | | | | | | |
A | | | C A | | | C
| | | | | | | | | |
| | | | | | | | | |
skipping to change at page 20, line 26 skipping to change at page 26, line 15
much similar as the inter-area case: ASBRs expanding the ERO over the much similar as the inter-area case: ASBRs expanding the ERO over the
next AS may remove the XRO subobjects located in that AS. Note that next AS may remove the XRO subobjects located in that AS. Note that
this can only be done by ingress ASBRs (the ASBR where the LSP is this can only be done by ingress ASBRs (the ASBR where the LSP is
entering the AS). entering the AS).
Discussion on the length of the XRO: the XRO is bounded by the length Discussion on the length of the XRO: the XRO is bounded by the length
of the RRO of the primary LSP. of the RRO of the primary LSP.
Suppose that SRLG protection is required, and the ASs crossed by the Suppose that SRLG protection is required, and the ASs crossed by the
main LSP use a consistent way of allocating SRLG-ids to the links main LSP use a consistent way of allocating SRLG-ids to the links
(i.e. the ASs use a single SRLG space). In this case, the SRLG-ids of (i.e. the ASs use a single SRLG space). In this case, the SRLG-ids
each link used by the main LSP can be recorded by means of the RRO, of each link used by the main LSP can be recorded by means of the
which are then used by the XRO. If the SRLG-ids are only meaningfull RRO, which are then used by the XRO. If the SRLG-ids are only
local to the AS, putting SRLG-ids in the XRO crossing many ASs makes meaningfull local to the AS, putting SRLG-ids in the XRO crossing
no sense. More details on the method of providing SRLG protection for many ASs makes no sense. More details on the method of providing
inter-AS LSPs can be found in [INTERAS]. Basically, the link IP SRLG protection for inter-AS LSPs can be found in [INTERAS].
address of the inter-AS link used by the primary LSP is put into the Basically, the link IP address of the inter-AS link used by the
XRO of the Path message of the detour LSP or bypass tunnel. The ASBR primary LSP is put into the XRO of the Path message of the detour LSP
where the detour LSP or bypass tunnel is entering the AS can or bypass tunnel. The ASBR where the detour LSP or bypass tunnel is
translate this into the list of SRLG-ids known to the local AS. entering the AS can translate this into the list of SRLG-ids known to
the local AS.
Discussion on the length of the XRO: the XRO only contains 1 subob- Discussion on the length of the XRO: the XRO only contains 1 subob-
ject, which contains the IP address of the inter-AS link traversed by ject, which contains the IP address of the inter-AS link traversed by
the primary LSP (in the assumption that the primary LSP and detour the primary LSP (in the assumption that the primary LSP and detour
LSP or bypass tunnel are leaving the AS in the same area, and they LSP or bypass tunnel are leaving the AS in the same area, and they
are also entering the next AS in the same area). are also entering the next AS in the same area).
A.3 Protection in the GMPLS overlay model A.3 Protection in the GMPLS overlay model
When an edge-node wants to establish an LSP towards another edge-node When an edge-node wants to establish an LSP towards another edge-node
over an optical core network as described in [OVERLAY] (see figure over an optical core network as described in [OVERLAY] (see figure
A.2), the XRO can be used for multiple purposes. A.2), the XRO can be used for multiple purposes.
Overlay Overlay Overlay Overlay
Network +----------------------------------+ Network Network +--------------------------------+ Network
+----------+ | | +----------+ +----------+ | | +----------+
| +----+ | | +-----+ +-----+ +-----+ | | +----+ | | +----+ | | +-----+ +-----+ +-----+ | | +----+ |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| --+ EN1+-+-----+--+ CN1 +----+ CN2 +----+ CN3 +---+-----+-+ EN3+-- | | --+ EN1+-+-----+--+ CN1 +---+ CN2 +---+ CN3 +---+-----+-+ EN3+-- |
| | | | +--+--+ | | | | +---+--+ | | | | | | | | +--+--+ | | | | +---+--+ | | | |
| +----+ | | | +--+--+ +--+--+ +--+--+ | | | +----+ | | +----+ | | | +--+--+ +--+--+ +--+--+ | | | +----+ |
| | | | | | | | | | | | | | | | | | | | | |
+----------+ | | | | | | | +----------+ +----------+ | | | | | | | +----------+
| | | | | | | | | | | | | |
+----------+ | | | | | | | +----------+ +----------+ | | | | | | | +----------+
| | | | +--+--+ | +--+--+ | | | | | | | | +--+--+ | +--+--+ | | | |
| +----+ | | | | | +-------+ | | | | +----+ | | +----+ | | | | | +------+ | | | | +----+ |
| | +-+--+ | | CN4 +---------------+ CN5 | | +--+-+ | | | | +-+--+ | | CN4 +-------------+ CN5 | | +--+-+ | |
| --+ EN2+-+-----+--+ | | +---+-----+-+ EN4+-- | | --+ EN2+-+-----+--+ | | +---+-----+-+ EN4+-- |
| | | | | +-----+ +-----+ | | | | | | | | | | +-----+ +-----+ | | | | |
| +----+ | | | | +----+ | | +----+ | | | | +----+ |
| | +----------------------------------+ | | | | +--------------------------------+ | |
+----------+ Core Network +----------+ +----------+ Core Network +----------+
Overlay Overlay Overlay Overlay
Network Network Network Network
Legend: EN - Edge Node Legend: EN - Edge Node
CN - Core Node CN - Core Node
Figure A.2 Figure A.2
A first application is where an edge-node wants to establish multiple A first application is where an edge-node wants to establish multiple
LSPs towards the same destinatin edge-node, and these LSPs need to LSPs towards the same destinatin edge-node, and these LSPs need to
skipping to change at page 21, line 46 skipping to change at page 27, line 46
links used by the first LSP with the indicition to avoid the SRLGs of links used by the first LSP with the indicition to avoid the SRLGs of
these links. This information can be used by CN1 to compute a path these links. This information can be used by CN1 to compute a path
for the second LSP. If the core network consists of multiple areas, for the second LSP. If the core network consists of multiple areas,
then the SRLG-ids have to be listed in the XRO. The same example then the SRLG-ids have to be listed in the XRO. The same example
applies to nodes and links. applies to nodes and links.
Another application is where the edge-node wants to set up a backup Another application is where the edge-node wants to set up a backup
LSP that is also protecting the links between the edge-nodes and LSP that is also protecting the links between the edge-nodes and
core-nodes. For instance, when EN2 establishes an LSP to EN4, it core-nodes. For instance, when EN2 establishes an LSP to EN4, it
sends a Path message to CN4, which computes a path towards EN4 over sends a Path message to CN4, which computes a path towards EN4 over
for instance CN5. When EN2 gets back the RRO of that LSP, it can sig- for instance CN5. When EN2 gets back the RRO of that LSP, it can
nal a new LSP to CN1 with EN4 as destination and the XRO computed sig- nal a new LSP to CN1 with EN4 as destination and the XRO
based on the RRO of the first LSP. Based on this information, CN1 can computed based on the RRO of the first LSP. Based on this
compute a path that has the requested diversaty properties (e.g, a information, CN1 can compute a path that has the requested diversaty
path going over CN2, CN3 and then to EN4). properties (e.g, a path going over CN2, CN3 and then to EN4).
It is clear that in these examples, the core-node may not edit the It is clear that in these examples, the core-node may not edit the
RRO in a Resv message such that it includes only the subobjects from RRO in a Resv message such that it includes only the subobjects from
the egress core-node through the egress edge-node. the egress core-node through the egress edge-node.
A.4 LSP protection inside a single area A.4 LSP protection inside a single area
The XRO can also be used inside a single area. Take for instance a The XRO can also be used inside a single area. Take for instance a
network where the TE extensions of the IGPs as described in [OSPF-TE] network where the TE extensions of the IGPs as described in [RFC3630]
and [ISIS-TE] are not used, and hence each node has to select a and [RFC3784] are not used, and hence each node has to select a
next-hop and possibly crankback [CRANKBACK] has to be used when there next-hop and possibly crankback [CRANKBACK] has to be used when there
is no viable next-hop. In this case, when signaling a backup LSP, the is no viable next-hop. In this case, when signaling a backup LSP,
XRO can be put in the Path message to exclude the links, nodes or the XRO can be put in the Path message to exclude the links, nodes or
SRLGs of the primary LSP. An alternative to provide this functional- SRLGs of the primary LSP. An alternative to provide this functional-
ity would be to indicate in the Path message of the backup LSP, the ity would be to indicate in the Path message of the backup LSP, the
primary LSP together witn an indication which type of protection is primary LSP together witn an indication which type of protection is
required. This latter solution would work for link and node protec- required. This latter solution would work for link and node protec-
tion, but not for SRLG protection. tion, but not for SRLG protection.
Discussion on the length of the XRO: when link or node protection is Discussion on the length of the XRO: when link or node protection is
requested, the XRO is of the same length as the RRO of the primary requested, the XRO is of the same length as the RRO of the primary
LSP. For SRLG protection, the XRO has to list all SRLGs that are LSP. For SRLG protection, the XRO has to list all SRLGs that are
crossed by the primary LSP. Note that for SRLG protection, the link crossed by the primary LSP. Note that for SRLG protection, the link
IP address to reference the SRLGs of that link cannot be used since IP address to reference the SRLGs of that link cannot be used since
the TE extensions of the IGPs are not used in this example, hence, a the TE extensions of the IGPs are not used in this example, hence, a
node cannot translate any link IP address located in that area to its node cannot translate any link IP address located in that area to its
SRLGs. SRLGs.
16. Full Copyright Statement Intellectual Property Statement
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