Network Working Group Fatai Zhang
Internet-Draft Dan Li
Intended status: Standards Track Huawei
Expires: January 2011 July 05, 2010
RSVP-TE Extensions for Configuration SRLG of an FA
draft-zhang-ccamp-srlg-fa-configuration-00.txt
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Abstract
This memo provides extensions for the Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) for the support of the automatic
configuration the SRLG of the Forwarding Adjacency (FA).
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Table of Contents
1. Introduction.................................................2
2. RSVP-TE Requirements.........................................4
2.1. FA SRLG Indication......................................4
2.2. FA SRLG Collecting......................................4
2.3. FA SRLG Update..........................................4
3. RSVP-TE Extensions...........................................4
3.1. FA SRLG Indication......................................4
3.2. SRLG Information Object.................................4
3.3. Signaling Procedures....................................5
4. Manageability Considerations.................................5
5. IANA Considerations..........................................5
6. Security Considerations......................................6
7. References...................................................6
1. Introduction
An LSP is advertised as a Traffic Engineering (TE) link by a
Generalized MPLS (GMPLS) node that created the LSP, which is referred
to as the "forwarding adjacency LSP", or FA-LSP. Such a link is a
"forwarding adjacency" (FA). [RFC 4206] describes the signaling and
routing aspects of the FA-LSP.
[RFC 3477] describes how to create an unnumbered FA and advertise it
as an unnumbered TE link automatically. [LSP-Hierarchy-bis] defines
the extensions to RSVP-TE to cover other FA advertising scenarios,
e.g. signaling of numbered FAs, Signaling an LSP for Use in a Link
Bundle and Signaling an LSP For use in Another Network.
In order to advertise the FAs automatically, the attributes of the FA
need to be configured automatically after the setup of the FAs. The
following attributes are described in [RFC 4206]:
o Link Type (OSPF Only, point-to-point)
o Link ID (OSPF Only, the Router ID of the remote-end of FA-LSP)
o Local and Remote Interface IP Address
o Local and Remote Link Identifiers
o Traffic Engineering Metric
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o Maximum Bandwidth
o Unreserved Bandwidth
o Resource Class/Color
o Interface Switching Capability
o SRLG Information
[RFC 4206] describes how to set the TE metric, maximum bandwidth,
unreserved bandwidth, resource class and interface switching
capability. [LSP-Hierarchy-bis] updates [RFC 4206] to provide
solutions on how to create H-LSP and advertise FA.
As described in Section 3.1.10 of [RFC 4206], an FA advertisement
could contain the information about the Shared Risk Link Groups (SRLG)
for the path taken by the FA-LSP associated with that FA. This
information may be used for SRLG disjoint path computation by other
LSRs. The SRLG information of the FA is the union of the SRLGs of the
TE links and nodes that make up the FA-LSP path.
In the client/server networks, the detailed path information that
passes through the server network is usually not provided to end
points of the FA in the client layer because of confidential
consideration. In addition, for the client/server networks, usually
they have separate routing instance, so the end points of the FA can
not get the SRLG information of FA-LSP.
Therefore, the SRLG information of the FA needs to be configured
manually by operator when advertising the FA. However, for manually
configuration, there are some disadvantages mentioned in Section
1.3.4 of [LSP-Hierarchy-bis].
In addition, Section 1.2 of [LSP-Hierarchy-bis] describes it is
desirable to have a kind of automatic mechanism to advertise the FA
(i.e., to signal an LSP and automatically coordinate its use and
advertisement in any of the ways with minimum involvement from an
operator).
Therefore, in order to make the FA advertisement completely
automatically, this document provides an automatic mechanism to
configure the SRLG of FA automatically.
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2. RSVP-TE Requirements
2.1. FA SRLG Indication
The head nodes of the FA-LSP must be capable of indicating whether
the SRLG information of the FA-LSP should be collected during the
signaling procedure of setting up an FA-LSP.
2.2. FA SRLG Collecting
The SRLG information can be collected during the setup of an FA-LSP.
Then the endpoints of the FA-LSP can get the SRLG information and
configure it to the corresponding FA link automatically.
2.3. FA SRLG Update
When the SRLG information changes, the endpoints of the FA-LSP need
to be capable of update the SRLG information of the corresponding FA
link. It means that the signaling needs to be capable of updating the
newly SRLG information to the endpoints.
3. RSVP-TE Extensions
3.1. FA SRLG Indication
The LSP_TUNNEL_INTERFACE_ID Object defined in [LSP-Hierarchy-bis] is
extended by adding a new flag (S flag) to the Action field:
-+-+-+-+-+-+-+-
| | |S|H|B|R|T|P|
-+-+-+-+-+-+-+-
S-flag (SRLG indication)
0 means that the endpoints do not need the SRLG information.
1 means that the endpoints need the SRLG information.
3.2. SRLG Information Object
An SRLG information is defined to carry the SRLG information of the
FA-LSP path. The Class-Num and the C-Type of the SRLG Information
Object need to be assigned by the IANA.
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Class-Num | C-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRLG ID (4 bytes) |
// ...... //
| SRLG ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The SRLG ID list carries the SRLG information of the FA-LSP. This
object can be carried in a Path/Resv message.
The SRLG information can be added to the Path/Resv message hop by hop.
Then the endpoints of the FA-LSP can get the SRLG information of the
path.
3.3. Signaling Procedures
When an FA head node determine that it needs to get the SRLG
information of the FA-LSP before setting up the FA-LSP, it sets the S
flag in the Action field of the LSP_TUNNEL_INTERFACE_ID Object when
it sends the Path message to the downstream node. The downstream
nodes record the SRLG information in the SRLG Information Object hop
by hop. Then the tail node of the FA-LSP can get the SRLG information
from the RRO.
The tail node also needs to set the S flag in the Action field of the
LSP_TUNNEL_INTERFACE_ID Object when it sends the Resv message to the
upstream node. The upstream nodes record the SRLG information in the
SRLG Information Object hop by hop. Then the head node of the FA-LSP
can get the SRLG information from the RRO.
Based on the above procedure, the endpoints can get the SRLG
information automatically. Then the endpoints can configure the SRLG
information of the FA and advertise it to the routing instance based
on the procedure described in [LSP-Hierarchy-bis].
4. Manageability Considerations
TBD.
5. IANA Considerations
TBD.
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6. Security Considerations
TBD.
7. References
[LSP-Hierarchy-bis] K. Shiomoto, A. Farrel, " Procedures for
Dynamically Signaled Hierarchical Label Switched Paths ",
draft-ietf-ccamp-lsp-hierarchy-bis-08, August 2010.
[RFC 4206] K. Kompella, Y. Rekhter, " Label Switched Paths (LSP)
Hierarchy with Generalized Multi-Protocol Label Switching
(GMPLS) Traffic Engineering (TE) ", rfc4206, October 2005.
[RFC 4874] CY. Lee, A. Farrel, S. De Cnodder, " Exclude Routes -
Extension to Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) ", rfc4874, April 2007.
[RFC 3477] K. Kompella, Y. Rekhter, " Signalling Unnumbered Links in
Resource ReSerVation Protocol - Traffic Engineering (RSVP-
TE) ", rfc3477, January 2003.
Authors' Addresses
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Fatai Zhang
Huawei Technologies
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28972912
Email: zhangfatai@huawei.com
Dan Li
Huawei Technologies
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28970230
Email: danli@huawei.com
Xiaobing Zi
Huawei Technologies
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28973229
Email: zixiaobing@huawei.com
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