draft-ietf-ccamp-rsvp-te-exclude-route-04.txt   draft-ietf-ccamp-rsvp-te-exclude-route-05.txt 
Network Working Group CY. Lee Network Working Group CY. Lee
Internet-Draft Alcatel Internet-Draft A. Farrel (Old Dog Consulting)
Expires: January 18, 2006 A. Farrel Expires: February 26, 2006 S. De Cnodder (Alcatel)
Old Dog Consulting August 26, 2005
S. De Cnodder
Alcatel
July 17, 2005
Exclude Routes - Extension to RSVP-TE Exclude Routes - Extension to RSVP-TE
draft-ietf-ccamp-rsvp-te-exclude-route-04.txt draft-ietf-ccamp-rsvp-te-exclude-route-05.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 1, line 37 skipping to change at page 1, line 34
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on January 18, 2006. This Internet-Draft will expire on February 26, 2006.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
The RSVP-TE specification, "RSVP-TE: Extensions to RSVP for LSP The RSVP-TE specification, "RSVP-TE: Extensions to RSVP for LSP
Tunnels" (RFC 3209) and GMPLS extensions to RSVP-TE, "Generalized 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
skipping to change at page 3, line 5 skipping to change at page 2, line 12
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.
Table of Contents Requirements notation
1. Requirements notation . . . . . . . . . . . . . . . . . . . . 4
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1 Scope of Exclude Routes . . . . . . . . . . . . . . . . . 6
2.2 Relationship to MPLS TE MIB . . . . . . . . . . . . . . . 7
3. Shared Risk Link Groups . . . . . . . . . . . . . . . . . . . 8
3.1 SRLG ERO Subobject . . . . . . . . . . . . . . . . . . . . 8
4. Exclude Route List . . . . . . . . . . . . . . . . . . . . . . 10
4.1 Exclude Route Object (XRO) . . . . . . . . . . . . . . . . 10
4.1.1 IPv4 prefix Subobject . . . . . . . . . . . . . . . . 11
4.1.2 IPv6 Prefix Subobject . . . . . . . . . . . . . . . . 12
4.1.3 Unnumbered Interface ID Subobject . . . . . . . . . . 13
4.1.4 Autonomous System Number Subobject . . . . . . . . . . 14
4.1.5 SRLG Subobject . . . . . . . . . . . . . . . . . . . . 15
4.2 Processing Rules for the Exclude Route Object (XRO) . . . 15
5. Explicit Exclusion Route . . . . . . . . . . . . . . . . . . . 18
5.1 Explicit Exclusion Route Subobject (EXRS) . . . . . . . . 18
5.2 Processing Rules for the Explicit Exclusion Route
Subobject (EXRS) . . . . . . . . . . . . . . . . . . . . . 19
6. Processing of XRO together with EXRS . . . . . . . . . . . . . 21
7. Minimum compliance . . . . . . . . . . . . . . . . . . . . . . 22
8. Security Considerations . . . . . . . . . . . . . . . . . . . 23
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
9.1 New RSVP-TE Class Numbers . . . . . . . . . . . . . . . . 24
9.2 New ERO Subobject Type . . . . . . . . . . . . . . . . . . 24
9.3 New ERO and XRO Subobject Type . . . . . . . . . . . . . . 24
9.4 New Error Codes . . . . . . . . . . . . . . . . . . . . . 25
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 26
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 27
11.1 Normative References . . . . . . . . . . . . . . . . . . . 27
11.2 Informational References . . . . . . . . . . . . . . . . . 27
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 28
A. applications . . . . . . . . . . . . . . . . . . . . . . . . . 29
A.1 Inter-area LSP protection . . . . . . . . . . . . . . . . 29
A.2 Inter-AS LSP protection . . . . . . . . . . . . . . . . . 30
A.3 Protection in the GMPLS overlay model . . . . . . . . . . 31
A.4 LSP protection inside a single area . . . . . . . . . . . 33
Intellectual Property and Copyright Statements . . . . . . . . 34
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].
2. Introduction Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Scope of Exclude Routes . . . . . . . . . . . . . . . . . 5
1.2 Relationship to MPLS TE MIB . . . . . . . . . . . . . . . 6
2. Shared Risk Link Groups . . . . . . . . . . . . . . . . . . . 6
2.1 SRLG ERO Subobject . . . . . . . . . . . . . . . . . . . . 6
3. Exclude Route List . . . . . . . . . . . . . . . . . . . . . . 7
3.1 Exclude Route Object (XRO) . . . . . . . . . . . . . . . . 7
3.1.1 IPv4 prefix Subobject . . . . . . . . . . . . . . . . 9
3.1.2 IPv6 Prefix Subobject . . . . . . . . . . . . . . . . 10
3.1.3 Unnumbered Interface ID Subobject . . . . . . . . . . 11
3.1.4 Autonomous System Number Subobject . . . . . . . . . . 12
3.1.5 SRLG Subobject . . . . . . . . . . . . . . . . . . . . 12
3.2 Processing Rules for the Exclude Route Object (XRO) . . . 12
4. Explicit Exclusion Route . . . . . . . . . . . . . . . . . . . 14
4.1 Explicit Exclusion Route Subobject (EXRS) . . . . . . . . 14
4.2 Processing Rules for the Explicit Exclusion Route 6
Subobject (EXRS) . . . . . . . . . . . . . . . . . . . . . 17
5. Processing of XRO together with EXRS . . . . . . . . . . . . . 16
6. Minimum compliance . . . . . . . . . . . . . . . . . . . . . . 17
7. Security Considerations . . . . . . . . . . . . . . . . . . . 17
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
8.1 New RSVP-TE Class Numbers . . . . . . . . . . . . . . . . 18
8.2 New ERO Subobject Type . . . . . . . . . . . . . . . . . . 18
8.3 New ERO and XRO Subobject Type . . . . . . . . . . . . . . 18
8.4 New Error Codes . . . . . . . . . . . . . . . . . . . . . 18
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 18
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
10.1 Normative References . . . . . . . . . . . . . . . . . . . 19
10.2 Informational References . . . . . . . . . . . . . . . . . 19
11. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 20
Apendix A. Aplications . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction
The RSVP-TE specification [RFC3209] and GMPLS extensions [RFC3473] The RSVP-TE specification [RFC3209] and GMPLS extensions [RFC3473]
allow abstract nodes and resources to be explicitly included in a allow abstract nodes and resources to be explicitly included in a
path setup, using the Explicit Route Object (ERO). 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 selecting a route through a specific resource. This is a special
case of distributed path calculation in the network. case of distributed path calculation in the network.
skipping to change at page 5, line 30 skipping to change at page 4, line 30
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. Exclusion of certain abstract nodes or resources between a 2. Exclusion of certain abstract nodes or resources between a
specific pair of abstract nodes present in an ERO. Such specific specific pair of abstract nodes present in an ERO. Such specific
exclusions are referred to as Explicit Exclusion Route. exclusions 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 introduced respectively. object and a new ERO subobject are introduced respectively.
1. A new RSVP-TE object is introduced to convey the Exclude Route - 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 - The second type of exclusion is achieved through a modification to
to the existing ERO. A new ERO subobject type the Explicit the existing ERO. A new ERO subobject type the Explicit Exclusion
Exclusion Route Subobject (EXRS) is introduced to indicate an Route Subobject (EXRS) is introduced to indicate an exclusion
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 path or between two abstract nodes specified in an explicit whole path or between two abstract nodes specified in an explicit
path. 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 and signaled in either of the two exclusion methods described above and
this document does not assume or preclude any other usage for this this document does not assume or preclude any other usage for this
subobject. This subobject might also be appropriate for use within subobject. This subobject might also be appropriate for use within
Explicit Routes or Record Routes, but this is outside the scope of Explicit Routes or Record Routes, but this is outside the scope of
this document. this document.
2.1 Scope of Exclude Routes 1.1 Scope of Exclude Routes
This document does not preclude a route exclusion from listing This document does not preclude a route exclusion from listing
arbitrary nodes or network elements to avoid. The intent is, arbitrary nodes or network elements to avoid. The intent is,
however, to indicate only the minimal number of subobjects to be however, to indicate only the minimal number of subobjects to be
avoided. For instance it may be necessary to signal only the SRLGs avoided. For instance it may be necessary to signal only the SRLGs
(or Shared Risk Groups) to avoid. (or Shared 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 with
areas. 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
| | | |
| ERO: (B3-strict, B4-strict, BC2-strict, Egress-loose) | ERO: (B3-strict, B4-strict, BC2-strict, Egress-loose)
| XRO: (BC1, C1, C2) | XRO: (BC1, C1, C2)
| |
ERO: (A3-strict, A4-strict, AB2-strict, Egress-loose) ERO: (A3-strict, A4-strict, AB2-strict, Egress-loose)
XRO: (AB1, B1, B2, BC1, C1, C2, Egress) XRO: (AB1, B1, B2, BC1, C1, C2, Egress)
Figure 1 : Domains Corresponding to IGP Areas
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 example above. The protection path must avoid all nodes on the
primary path. The exclusions for area A are handled during primary path. The exclusions for area A are handled during
Constrained Shortest Path First (CSPF) computation at Ingress, so the Constrained Shortest Path First (CSPF) computation at Ingress, so the
ERO and XRO signaled at Ingress could be (A3-strict, A4-strict, AB2- ERO and XRO signaled at Ingress could be (A3-strict, A4-strict, AB2-
strict, Egress-loose) and (AB1, B1, B2, BC1, C1, C2) respectively. strict, Egress-loose) and (AB1, B1, B2, BC1, C1, C2) respectively.
At AB2 the ERO and XRO could be (B3-strict, B4-strict, BC2-strict, At AB2 the ERO and XRO could be (B3-strict, B4-strict, BC2-strict,
Egress-loose) and (BC1, C1, C2) respectively. At BC2 the ERO could Egress-loose) and (BC1, C1, C2) respectively. At BC2 the ERO could
be (C3-strict, C4-strict, Egress-strict) and an XRO is not needed be (C3-strict, C4-strict, Egress-strict) and an XRO is not needed
from BC2 onwards. 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.
2.2 Relationship to MPLS TE MIB 1.2 Relationship to MPLS TE MIB
[RFC3812] defines managed objects for managing and modeling MPLS- [RFC3812] defines managed objects for managing and modeling MPLS-
based traffic engineering. Included in [RFC3812] is a means to based traffic engineering. Included in [RFC3812] is a means to
configure explicit routes for use on specific LSPs. This configure explicit routes for use on specific LSPs. This
configuration 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 be necessary to signal those exclusions. This document offers a
means of doing this signaling. means of doing this signaling.
3. Shared Risk Link Groups 2. 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-
RTG]. An SRLG ERO subobject is introduced such that it can be used RTG]. An SRLG ERO subobject is introduced such that it can be used
in the exclusion methods as described in the following sections. in the exclusion methods as described in the following sections.
This document does not assume or preclude any other usage for this This document does not assume or preclude any other usage for this
subobject. This subobject might also be appropriate for use within subobject. This subobject might also be appropriate for use within
Explicit Routes or Record Routes, but this is outside the scope of Explicit Routes or Record Routes, but this is outside the scope of
this document. this document.
3.1 SRLG ERO Subobject 2.1 SRLG ERO Subobject
The format of the ERO and its subobjects are defined in [RFC3209]. 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
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 For exclusions (as used by XRO and EXRS defined in this
document), the L bit SHOULD be set to zero and ignored. document), the L bit SHOULD be set to zero and ignored.
Type Type
skipping to change at page 10, line 5 skipping to change at page 7, line 32
SRLG Id SRLG Id
The 32 bit identifier of the SRLG. The 32 bit identifier of the SRLG.
Reserved Reserved
This field is reserved. It MUST be set to zero on transmission This field is reserved. It MUST be set to zero on transmission
and MUST be ignored on receipt. and MUST be ignored on receipt.
4. Exclude Route List 3. Exclude Route List
The exclude route identifies a list of abstract nodes that should not The exclude route identifies a list of abstract nodes that should 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.
4.1 Exclude Route Object (XRO) 3.1 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 by IANA, C_Type = 1 Class = TBD by IANA, 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
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. This specification adapts ERO length data items called subobjects. This specification adapts ERO
subojbects as defined in [RFC3209], [RFC3473], and [RFC3477] for use subojbects as defined in [RFC3209], [RFC3473], and [RFC3477] for
in route exclusions. The SRLG ERO subobject as defined in Section 3 use in route exclusions. The SRLG ERO subobject as defined in
of this document and its processing within ERO have not been defined Section 2 of this document and its processing within ERO have not
before. The SRLG ERO subobject is defined here for use with route been defined before. The SRLG ERO subobject is defined here for use
exclusions. with route exclusions.
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 by IANA SRLG
The defined values for Type above are specified in [RFC3209] and in The defined values for Type above are specified in [RFC3209] and in
this document. this document.
The concept of loose or strict hops has no meaning in route The concept of loose or strict hops has no meaning in route
exclusion. The L bit, defined for ERO subobjects in [RFC3209], is exclusion. The L bit, defined for ERO subobjects in [RFC3209], is
reused 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).
Subobjects 1, 2, and 4 refer to an interface or a set of interfaces. Subobjects 1, 2, and 4 refer to an interface or a set of interfaces.
An Attribute octet is introduced in these subobjects to indicate the An Attribute octet is introduced in these subobjects to indicate the
attribute (e.g. interface, node, SRLG) associated with the interfaces attribute (e.g. interface, node, SRLG) associated with the interfaces
that should be excluded from the path. For instance, the attribute that should be excluded from the path. For instance, the attribute
node allows a whole node to be excluded from the path by specifying node allows a whole node to be excluded from the path by specifying
an interface of that node in the XRO subobject, in contrast to the an interface of that node in the XRO subobject, in contrast to the
attribute interface, which allows a specific interface (or multiple attribute interface, which allows a specific interface (or multiple
interfaces) to be excluded from the path without excluding the whole interfaces) to be excluded from the path without excluding the whole
nodes. The attribute SRLG allows all SRLGs associated with an nodes. The attribute SRLG allows all SRLGs associated with an
interface to be excluded from the path. interface to be excluded from the path.
4.1.1 IPv4 prefix Subobject 3.1.1 IPv4 prefix 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 | 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
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 attribute values
0 indicates that the interface or set of interfaces 0 indicates that the interface or set of interfaces
associated with the IPv4 prefix should be excluded or avoided associated with the IPv4 prefix should be excluded or avoided
node node
Node attribute value
1 indicates that the node or set of nodes associated with 1 indicates that the node or set of nodes associated with
the IPv4 prefix should be excluded or avoided the IPv4 prefix should be excluded or avoided
SRLG SRLG attribute values
2 indicates that all the SRLGs associated with the IPv4 2 indicates that all the SRLGs associated with the IPv4
prefix should be excluded or avoided prefix should be excluded or avoided
The rest of the fields are as defined in [RFC3209]. The rest of the fields are as defined in [RFC3209].
4.1.2 IPv6 Prefix Subobject 3.1.2 IPv6 Prefix 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 | IPv6 address (16 bytes) | |L| Type | Length | IPv6 address (16 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 address (continued) | | IPv6 address (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv6 address (continued) | | IPv6 address (continued) |
skipping to change at page 13, line 4 skipping to change at page 10, line 29
| IPv6 address (continued) | Prefix Length | Attribute | | IPv6 address (continued) | Prefix Length | Attribute |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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 attribute value
0 indicates that the interface or set of interfaces associated 0 indicates that the interface or set of interfaces associated
with the IPv6 prefix should be excluded or avoided with the IPv6 prefix should be excluded or avoided
node Node attribute value
1 indicates that the node or set of nodes associated with 1 indicates that the node or set of nodes associated with
the IPv6 prefix should be excluded or avoided the IPv6 prefix should be excluded or avoided
SRLG SRLG attribute value
2 indicates that all the SRLG associated with the IPv6 2 indicates that all the SRLG associated with the IPv6
prefix should be excluded or avoided prefix should be excluded or avoided
The rest of the fields are as defined in [RFC3209]. The rest of the fields are as defined in [RFC3209].
4.1.3 Unnumbered Interface ID Subobject 3.1.3 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) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TE Router ID | | TE Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 14, line 4 skipping to change at page 11, line 24
| TE Router ID | | TE 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 attribute value
0 indicates that the Interface ID specified should be 0 indicates that the Interface ID specified should be
excluded or avoided excluded or avoided
node Node attribute value
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 information from subobjects of an RRO convenient to use information from subobjects of an RRO
as defined in [RFC3477], in specifying the exclusions). as defined in [RFC3477], in specifying the exclusions).
SRLG SRLG attribute value
2 indicates that all the SRLGs associated with the 2 indicates that all the SRLGs associated with the
interface should be excluded or avoided interface should be excluded or avoided
Reserved Reserved
This field is reserved. It MUST be set to zero on transmission This field is reserved. It MUST be set to zero on transmission
and MUST be ignored on receipt. and MUST be ignored on receipt.
The rest of the fields are as defined in [RFC3477]. The rest of the fields are as defined in [RFC3477].
4.1.4 Autonomous System Number Subobject 3.1.4 Autonomous System Number Subobject
The meaning of the L bit is as follows: The meaning of the L bit is as follows:
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 [RFC3209]. There is no The rest of the fields are as defined in [RFC3209]. There is no
Attribute octet defined. Attribute octet defined.
4.1.5 SRLG Subobject 3.1.5 SRLG Subobject
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.
4.2 Processing Rules for the Exclude Route Object (XRO) 3.2 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 belonging Each abstract node may be a precisely specified IP address belonging
to a node, or an IP address with prefix identifying interfaces of a to a node, or an IP address with prefix identifying interfaces 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 [RFC3209] with the following additions: description in [RFC3209] with the following additions:
1. 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 that it is not a member of any of the abstract nodes in the XRO
if it is present in the Path message. If the node is a member of if it is present in the Path message. If the node is a member of
any of the abstract nodes in the XRO with the L-flag set to any of the abstract nodes in the XRO with the L-flag set to
"exclude", it should return a PathErr with the error code "exclude", it SHOULD return a PathErr with the error code
"Routing Problem" and error value of "Local node in Exclude "Routing Problem" and error value of "Local node in Exclude
Route". If there are SRLGs in the XRO, the node should check Route". If there are SRLGs in the XRO, the node SHOULD check
that the resources the node uses are not part of any SRLG with that the resources the node uses are not part of any SRLG with
the L-flag set to "exclude" that is specified in the XRO. If it the L-flag set to "exclude" that is specified in the XRO. If it
is, it should return a PathErr with error code "Routing Problem" is, it SHOULD return a PathErr with error code "Routing Problem"
and error value of "Local node in Exclude Route". and error value of "Local node in Exclude Route".
2. 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 SHOULDreturn 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 containing the IP address of a node and the attribute field is
set to "interface" or "SRLG". set to "interface" or "SRLG".
3. The subobjects in the ERO and XRO MUST NOT contradict each other. 3. The subobjects in the ERO and XRO MUST NOT contradict each other.
If a Path message is received that contains contradicting ERO and If a Path message is received that contains contradicting ERO and
XRO subobjects, then: XRO subobjects, then:
* subobjects in the XRO with the L flag not set (zero) MUST take - subobjects in the XRO with the L flag not set (zero) MUST take
precedence over the subobjects in the ERO - that is, a precedence over the subobjects in the ERO - that is, a
mandatory exclusion expressed in the XRO MUST be honored and mandatory exclusion expressed in the XRO MUST be honored and
an implementation MUST reject such a Path message. This means an implementation MUST reject such a Path message. This means
that a PathErr with error code "Routing Problem" and error that a PathErr with error code "Routing Problem" and error
value of "Route blocked by Exclude Route" is returned. value of "Route blocked by Exclude Route" is returned.
* subobjects in the XRO with the L flag set do not take - subobjects in the XRO with the L flag set do not take
precedence over ERO subobjects - that is, an implementation precedence over ERO subobjects - that is, an implementation
MAY choose to reject a Path message because of such a MAY choose to reject a Path message because of such a
contradiction, but MAY continue and set up the LSP (ignoring contradiction, but MAY continue and set up the LSP (ignoring
the XRO subobjects contradicting the ERO subobjects). the XRO subobjects contradicting the ERO subobjects).
4. When choosing a next hop or expanding an explicit route to 4. When choosing a next hop or expanding an explicit route to
include additional subobjects, a node: include additional subobjects, a node:
1. must not introduce an explicit node or an abstract node that a. 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 explicit nodes or abstract nodes The number of introduced explicit nodes or abstract nodes
with the L flag set to "avoid", which indicate that it is not with the L flag set to "avoid", which indicate that it is not
mandatory to be excluded but that it is less preferred, mandatory to be excluded but that it is less preferred,
should be minimised in the computed path. SHOULD be minimised in the computed path.
2. must not introduce links, nodes or resources identified by b. MUST NOT introduce links, nodes or resources identified by
the SRLG Id specified in the SRLG subobjects(s). The number the SRLG Id specified in the SRLG subobjects(s). The number
of 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 Note that the subobjects in the XRO is an unordered list of
subobjects. subobjects.
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, forward it uninspected and do not apply the support the XRO, forward it uninspected and do not apply the
extensions to ERO processing described above. This approach is extensions to ERO processing described above. This approach is
chosen to allow route exclusion to traverse parts of the network that chosen to allow route exclusion to traverse parts of the network that
are not capable of parsing or handling the new function. Note that are not capable of parsing or handling the new function. Note that
skipping to change at page 18, line 5 skipping to change at page 14, line 34
the 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.
In any case, a node MUST NOT introduce any explicit or abstract node In any case, a node MUST NOT introduce any explicit or abstract node
in the XRO (irrespective of the value of the L flag) that it also has in the XRO (irrespective of the value of the L flag) that it also has
introduced in the ERO. introduced in the ERO.
5. Explicit Exclusion Route 4. Explicit Exclusion Route
The Explicit Exclusion Route defines abstract nodes or resources The Explicit Exclusion Route defines abstract nodes or resources
(such as links, unnumbered interfaces or labels) that must not or (such as links, unnumbered interfaces or labels) that must not or
should not be used on the path between two inclusive abstract nodes should not be used on the path between two inclusive abstract nodes
or resources in the explicit route. or resources in the explicit route.
5.1 Explicit Exclusion Route Subobject (EXRS) 4.1 Explicit Exclusion Route Subobject (EXRS)
A new ERO subobject type is defined. The Explicit Exclusion Route A new ERO subobject type is defined. The Explicit Exclusion Route
Subobject (EXRS) has type [TBD by IANA]. Although the EXRS is an ERO Subobject (EXRS) has type [TBD by IANA]. Although the EXRS is an ERO
subobject and the XRO is reusing the ERO subobject, an EXRS MUST NOT subobject and the XRO is reusing the ERO subobject, an EXRS MUST NOT
be present in an XRO. An EXRS is an ERO subobject, which contains be present in an XRO. An EXRS is an ERO subobject, which contains
one or more subobjects in its own, called EXRS subobjects. one or more subobjects in its own, called EXRS subobjects.
The format of the EXRS is as follows: The format of the EXRS is as follows:
0 1 2 3 0 1 2 3
skipping to change at page 19, line 22 skipping to change at page 16, line 5
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 | |L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5.2 Processing Rules for the Explicit Exclusion Route Subobject (EXRS) 4.2 Processing Rules for the Explicit Exclusion Route Subobject (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. The processing rules of subobject that identifies an abstract node. The processing rules of
the EXRS are the same as the processing rule of the XRO within this the EXRS are the same as the processing rule of the XRO within this
scope. Multiple exclusions may be present between any pair of scope. Multiple exclusions may be present between any pair of
skipping to change at page 19, line 45 skipping to change at page 16, line 28
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 Exclusions may also indicate resources (such as unnumbered
interfaces, link ids, labels) that must not be used on the path to interfaces, link ids, labels) that must not be used on the path to
the 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 EXRS containing an abstract node in the ERO by the inclusion of an EXRS containing an
SRLG subobject. If the L-bit value in the SRLG subobject is zero, SRLG subobject. If the L-bit in the SRLG subobject is zero, the
the resources (nodes, links, etc.) identified by the SRLG MUST not be resources (nodes, links, etc.) identified by the SRLG MUST NOT be
used on the path to the next abstract node indicated in the ERO. If used on the path to the next abstract node indicated in the ERO. If
the L-bit is set, the resources identified by the SRLG SHOULD be the L-bit is set, the resources identified by the SRLG SHOULD be
avoided. avoided.
If a node is called upon to process an EXRS and does not support If a node is called upon to process an EXRS and does not support
handling of exclusions it will behave as described in [RFC3209] when handling of exclusions it will behave as described in [RFC3209] when
an unrecognized ERO subobject is encountered. This means that this an unrecognized ERO subobject is encountered. This means that this
node will return a PathErr with error code "Routing Error" and error node will return a PathErr with error code "Routing Error" and error
value "Bad Explicit Route Object" with the EXPLICIT_ROUTE object value "Bad Explicit Route Object" with the EXPLICIT_ROUTE object
inlcuded, truncated (on the left) to the offending EXRS. inlcuded, truncated (on the left) to the offending EXRS.
If the presence of EXRS precludes further forwarding of the Path If the presence of EXRS precludes further forwarding of the Path
message, the node should return a PathErr with the error code message, the node SHOULD return a PathErr with the error code
"Routing Problem" and error value of "Route blocked by Exclude "Routing Problem" and error value "Route blocked by Exclude Route".
Route".
6. Processing of XRO together with EXRS 5. Processing of XRO together with EXRS
When an LSR performs ERO expansion and finds both the XRO in the Path When an LSR performs ERO expansion and finds both the XRO in the Path
message and EXRS in the ERO, it MUST exclude all the SRLGs, nodes, message and EXRS in the ERO, it MUST exclude all the SRLGs, nodes,
links and resources listed in both places. Where some elements links and resources listed in both places. Where some elements
appears in both lists it MUST be handled according to the stricter appears in both lists it MUST be handled according to the stricter
exclusion request - that is, if one list says that an SRLG, node, exclusion request - that is, if one list says that an SRLG, node,
link or resource must be excluded and the other says only that it link or resource must be excluded and the other says only that it
should be avoided then the element MUST be excluded. should be avoided then the element MUST be excluded.
7. 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:
1. 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 - The IPv4 Prefix subobject MUST be supported with a prefix
length of 32, and an attribute value of "interface" and length of 32, and an attribute value of "interface" and
"node". Other prefix values and attribute values MAY be "node". Other prefix values and attribute values MAY be
supported. supported.
* The IPv6 Prefix subobject MUST be supported with a prefix - The IPv6 Prefix subobject MUST be supported with a prefix
length of 128, and an attribute value of "interface" and length of 128, and an attribute value of "interface" and
"node". Other prefix values and attribute values MAY be "node". Other prefix values and attribute values MAY be
supported. supported.
2. The EXRS MAY be supported. If supported, the same restrictions 2. The EXRS MAY be supported. If supported, the same restrictions
as for the XRO apply. as for the XRO apply.
3. If XRO or EXRS are supported, the implementation MUST be 3. If XRO or EXRS are supported, the implementation MUST be
compliant with the processing rules of the supported, not compliant with the processing rules of the supported, not
supported, or partially supported subobjects as specified within supported, or partially supported subobjects as specified within
this document. this document.
8. 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 [RFC3209] and [RFC3473]. Note that any security concerns that above [RFC3209] and [RFC3473]. Note that any security concerns that
exist with Explicit Routes should be considered with regard to route exist with Explicit Routes should be considered with regard to route
exclusions. exclusions.
9. IANA Considerations 8. IANA Considerations
It might be considered that an alternative approach would be to It might be considered that an alternative approach would be to
assign one of the bits of the ERO sub-object type field (perhaps the assign 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 top bit) to identify that a sub-object is intended for inclusion
rather than exclusion. However, [RFC3209] states that the type field rather than exclusion. However, [RFC3209] states that the type field
(seven bits) should be assigned as 0 - 63 through IETF consensus (seven bits) should be assigned as 0 - 63 through IETF consensus
action, 64 - 95 as first come first served, and 96 - 127 are reserved action, 64 - 95 as first come first served, and 96 - 127 are reserved
for private use. It would not be acceptable to disrupt existing for private use. It would not be acceptable to disrupt existing
implementations so the only option would be to split the IETF implementations so the only option would be to split the IETF
consensus range leaving only 32 sub-object types. It is felt that consensus range leaving only 32 sub-object types. It is felt that
that would be an unacceptably small number for future expansion of that would be an unacceptably small number for future expansion of
the protocol. the protocol.
9.1 New RSVP-TE Class Numbers 8.1 New RSVP-TE Class Numbers
One new class number is required for Exclude Route object (XRO) One new class number is required for Exclude Route object (XRO)
defined in section "Exclude Route Object (XRO)". defined in section "Exclude Route Object (XRO)".
EXCLUDE_ROUTE EXCLUDE_ROUTE
Class-Num of type 11bbbbbb Class-Num of type 11bbbbbb
Suggested value 232 Suggested value 232
Defined CType: 1 (Exclude Route) Defined CType: 1 (Exclude Route)
Subobjects 1, 2, 4 and 32 as for Explicit Route Object. Subobjects 1, 2, 4 and 32 as for Explicit Route Object.
Additional SRLG subobject as requested in "New ERO and XRO Additional SRLG subobject as requested in "New ERO and XRO
Subobject Type" Subobject Type"
9.2 New ERO Subobject Type 8.2 New ERO Subobject Type
The Explicit Exclusion Route subobject (EXRS) is defined in section The Explicit Exclusion Route subobject (EXRS) is defined in section
"Explicit Exclusion Route Subobject (EXRS)". This subobject may be "Explicit Exclusion Route Subobject (EXRS)". This subobject may be
present in the Explicit Route Object, but not in the Route Record present in the Explicit Route Object, but not in the Route Record
Object, nor in the new Exclude Route Object. Object, nor in the new Exclude Route Object.
Suggested value 33 Suggested value 33
9.3 New ERO and XRO Subobject Type 8.3 New ERO and XRO Subobject Type
The SRLG subobject is defined in section "SRLG ERO Subobject". This The SRLG subobject is defined in section "SRLG ERO Subobject". This
subobject may be present in the Exclude Route Object or in the subobject may be present in the Exclude Route Object or in the
Explicit Route Object, but not in the Route Record Object. Explicit Route Object, but not in the Route Record Object.
Suggested value 34 Suggested value 34
9.4 New Error Codes 8.4 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'
(24). (24).
Unsupported Exclude Route Subobject Type Suggested value 64 Unsupported Exclude Route Subobject Type Suggested value 64
Inconsistent Subobject Suggested value 65 Inconsistent Subobject Suggested value 65
Local Node in Exclude Route Suggested value 66 Local Node in Exclude Route Suggested value 66
Route Blocked by Exclude Route Suggested value 67 Route Blocked by Exclude Route Suggested value 67
10. Acknowledgments 9. Acknowledgments
This document reuses text from [RFC3209] 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!
11. References 10. References
11.1 Normative References 10.1 Normative References
[GMPLS-RTG] [GMPLS-RTG]
Kompella, K. and Y. Rekhter, "Routing Extensions in Kompella, K. and Y. Rekhter, "Routing Extensions in
Support of Generalized Multi-Protocol Label Switching", Support of Generalized Multi-Protocol Label Switching",
draft-ietf-ccamp-gmpls-routing-9.txt, work in progress, draft-ietf-ccamp-gmpls-routing, 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.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001. Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic (GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
in Resource ReSerVation Protocol - Traffic Engineering in Resource ReSerVation Protocol - Traffic Engineering
(RSVP-TE)", RFC 3477, January 2003. (RSVP-TE)", RFC 3477, January 2003.
11.2 Informational References 10.2 Informational References
[CRANKBACK] [CRANKBACK]
Farrel, A., Satyanarayana, A., Iwata, A., Ash, G., and S. Farrel, A., Satyanarayana, A., Iwata, A., Ash, G., and S.
Marshall-Unitt, "Crankback Signaling Extensions for MPLS Marshall-Unitt, "Crankback Signaling Extensions for MPLS
Signaling", draft-ietf-ccamp-crankback-02.txt, work in Signaling", draft-ietf-ccamp-crankback, work in progress.
progress, July 2004.
[INTERAS] De Cnodder, S. and C. Pelsser, "Protection for inter-AS [INTERAS] De Cnodder, S. and C. Pelsser, "Protection for inter-AS
MPLS tunnels", MPLS tunnels", draft-decnodder-ccamp-interas-protection,
draft-decnodder-ccamp-interas-protection-00.txt, work in work in progress.
progress, July 2004.
[INTERAS-REQ] [INTERAS-REQ]
Zhang, R. and JP. Vasseur, "MPLS Inter-AS Traffic Zhang, R. and JP. Vasseur, "MPLS Inter-AS Traffic
Engineering requirements", Engineering requirements",
draft-ietf-tewg-interas-mpls-te-req-09.txt, work in draft-ietf-tewg-interas-mpls-te-req, work in progress.
progress, September 2004.
[MPLS-BUNDLE] [MPLS-BUNDLE]
Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling
in MPLS Traffic Engineering", in MPLS Traffic Engineering", draft-ietf-mpls-bundle, work
draft-ietf-mpls-bundle-04.txt, work in progress, in progress.
July 2002.
[OVERLAY] Swallow, G., Drake, J., Ishimatsu, H., and Y. Rekhter, [OVERLAY] Swallow, G., Drake, J., Ishimatsu, H., and Y. Rekhter,
"GMPLS UNI: RSVP Support for the Overlay Model", "GMPLS UNI: RSVP Support for the Overlay Model",
draft-ietf-ccamp-gmpls-overlay-04.txt, work in progress, draft-ietf-ccamp-gmpls-overlay, work in progress.
April 2004.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630, (TE) Extensions to OSPF Version 2", RFC 3630,
September 2003. September 2003.
[RFC3784] Smit, H. and T. Li, "Intermediate System to Intermediate [RFC3784] Smit, H. and T. Li, "Intermediate System to Intermediate
System (IS-IS) Extensions for Traffic Engineering (TE)", System (IS-IS) Extensions for Traffic Engineering (TE)",
RFC 3784, June 2004. RFC 3784, June 2004.
[RFC3812] Srinivasan, C., Viswanathan, A., and T. Nadeau, [RFC3812] Srinivasan, C., Viswanathan, A., and T. Nadeau,
"Multiprotocol Label Switching (MPLS) Traffic Engineering "Multiprotocol Label Switching (MPLS) Traffic Engineering
(TE) Management Information Base (MIB)", RFC 3812, (TE) Management Information Base (MIB)", RFC 3812,
June 2004. June 2004.
Authors' Addresses 11. Authors' Addresses
Cheng-Yin Lee Cheng-Yin Lee
Alcatel Email: leecy@sympatico.ca
600 March Road.
Ottawa, Ontario
Canada K2K 2E6
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 B-2018 Antwerp
Belgium Belgium
Phone: +32 3 240 85 15 Phone: +32 3 240 85 15
Email: stefaan.de_cnodder@alcatel.be Email: stefaan.de_cnodder@alcatel.be
Appendix A. applications 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 a single object can be used case but the intention is to show that a single object can be used
for all the examples, hence making the XRO a rather generic object for all the examples, hence making the XRO a rather generic object
without having to define a solution and new objects for each new without having to define a solution and new objects for each new
application. application.
 End of changes. 

This html diff was produced by rfcdiff 1.25, available from http://www.levkowetz.com/ietf/tools/rfcdiff/