One document matched: draft-zhang-ccamp-srlg-fa-configuration-01.txt
Differences from draft-zhang-ccamp-srlg-fa-configuration-00.txt
Network Working Group Fatai Zhang
Internet-Draft Dan Li
Intended status: Standards Track Huawei
O. Gonzalez de Dios
Telefonica Investigacion y Desarrollo
C. Margaria. C
Nokia Siemens Networks
Expires: April 20, 2011 October 20, 2010
RSVP-TE Extensions for Configuration SRLG of an FA
draft-zhang-ccamp-srlg-fa-configuration-01.txt
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Abstract
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This memo provides extensions for the Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) for the support of the automatic
discovery of SRLG of an LSP.
Table of Contents
1. Introduction.................................................2
2. RSVP-TE Requirements.........................................4
2.1. SRLG Collection Indication..............................4
2.2. SRLG Collecting.........................................4
2.3. SRLG Update.............................................4
3. RSVP-TE Extensions...........................................4
3.1. SRLG Collection Indication..............................4
3.2. SRLG Information Object.................................4
3.3. Signaling Procedures....................................5
4. Manageability Considerations.................................5
5. IANA Considerations..........................................6
6. Security Considerations......................................6
7. References...................................................6
1. Introduction
As described in [RFC4206], H-LSP (Hierarchical LSP) can be used for
carrying one or more other LSPs. [LSP-Hierarchy-bis] further mentions
the implementation of H-LSP. In packet networks, e.g. MPLS networks,
H-LSP mechanism can be implemented by MPLS label stack. In non-packet
networks where the label is implicit, label stacks are not possible,
and H-LSPs rely on the ability to nest switching technologies. Thus,
for example, a lambda switch capable (LSC) LSP can carry a time
division multiplexing (TDM) LSP, but cannot carry another LSC LSP.
S-LSP (LSP Stitching), which is defined in [RFC5150], is an LSP that
represents a segment of another LSP, i.e., the S-LSP is viewed as one
hop by another LSP. As described in [LSP-Hierarchy-bis], in the data
plane the LSPs are stitched so that there is no label stacking or
nesting. Thus, an S-LSP must be of the same switching technology as
the end-to-end LSP that it facilitates.
Therefore, H-LSP mechanism can be used in both multi-domain and
multi-layer scenarios and S-LSP mechanism can only be used in multi-
domain scenario.
Both of the H-LSP and S-LSP can be advertised as a TE link in a GMPLS
routing instance for path computation purpose. As described in [LSP-
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Hierarchy-bis], if the LSP (H-LSP or S-LSP) is advertised in the same
instance of the control plane that advertises the TE links from which
the LSP is constructed, the LSP is called an FA.
In multi-domain or multi-layer context, the path information of an
LSP may not be provided to the ingress node for confidential reasons
and the ingress node may not run the same routing instance with the
intermediate nodes traversed by the path. In such scenarios, the
ingress node can not get the SRLG information of the path information
which the LSP traverse.
Even if the ingress node has the same routing instance with the
intermediate nodes traversed by the path, the path information of the
H-LSP or S-LSP may not be provided to the ingress node. Hence the
ingress node may also not know the SRLG of the path the LSP traverses.
In the case that the ingress node does not get the SRLG of the path
the LSP traverses(i.e. H-LSP or S-LSP), there are disadvantages as
follows:
o SRLG-disjoint path, for instance in case of end-to-end path
protection, cannot be calculated
o Intermediate nodes of a pre-planned shared restoration LSP cannot
correctly decide on the SRLG-disjointness between two PPRO
(PRIMARY_PATH_ROUTE Object)
o In case that an LSP is advertised as a TE-Link, the ingress node
cannot provide the correct SRLG for the TE-Link automatically
In case that an LSP is advertised as a TE-Link, the SRLG information
of the TE link needs to be configured manually or automatically.
However, for manually configuration, there are some disadvantages
(e.g., require configuration coordination and additional management;
manual errors may be introduced) 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).
Thus, in order to provide the SRLG information to the TE link
automatically when an LSP (H-LSP or S-LSP) is advertised as a TE link,
allow disjoint path calculation at ingress and allow correct pre-
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planned shared LSP to correctly share resource, this document
provides an automatic mechanism to collect the SRLG used by a LSP
automatically.
2. RSVP-TE Requirements
2.1. SRLG Collection Indication
The head nodes of the LSP must be capable of indicating whether the
SRLG information of the LSP should be collected during the signaling
procedure of setting up an LSP.
2.2. SRLG Collecting
The SRLG information can be collected during the setup of an LSP.
Then the endpoints of the LSP can get the SRLG information and use it
for routing, sharing and TE link configuration purposes.
2.3. SRLG Update
When the SRLG information changes, the endpoints of the LSP need to
be capable of updating the SRLG information of the path. It means
that the signaling needs to be capable of updating the newly SRLG
information to the endpoints.
3. RSVP-TE Extensions
3.1. SRLG Collection Indication
In order to indicate nodes that SRLG collection is desired, a new
flag in the SESSION_ATTRIBUTE is needed:
0x08 SRLG recording desired
This flag indicate that SRLG information should be recorded along the
LSP.
3.2. SRLG Information Object
An SRLG information object is defined to carry the SRLG information
of the LSP. 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 LSP. This object
can be carried in a Path/Resv message.
The SRLG ID can be added to the SRLG Information Object in a
Path/Resv message hop by hop. Then the endpoints of the LSP can get
the SRLG information of the path.
3.3. Signaling Procedures
When an LSP head node determines that it needs to get the SRLG
information of the LSP, it sets the ''SRLG recording desired'' in the
SESSION_ATTRIBUTE 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 LSP can get
the SRLG information from the SRLG Information Object.
When the tail node of the LSP receives the Path message and the ''SRLG
recording desired'' is set in the SESSION_ATTRIBUTE object, it can get
the SRLG information from the SRLG Information Object of the Path
message. Hence it can add the collected SRLG information into the
SRLG Information Object of a Resv message which will be forwarded hop
by hop in the upstream direction until it arrives the head node. Then
the head node can also get the SRLG information of the LSP from the
SRLG Information Object in the Resv message.
Based on the above procedure, the endpoints can get the SRLG
information automatically. Then the endpoints can for instance
configure the SRLG information and advertise it as a TE link to the
routing instance based on the procedure described in [LSP-Hierarchy-
bis].
4. Manageability Considerations
TBD.
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5. IANA Considerations
TBD.
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.
[RFC5150] Ayyangar, A., Vasseur, J.P, and Farrel, A., "Label Switched
Path Stitching with Generalized Multiprotocol Label
Switching Traffic Engineering (GMPLS TE)", RFC 5150,
February 2008.
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
Oscar Gonzalez de Dios
Telefonica Investigacion y Desarrollo
Emilio Vargas 6
Madrid, 28045
Spain
Phone: +34 913374013
Email: ogondio@tid.es
Cyril Margaria
Nokia Siemens Networks
St Martin Strasse 76
Munich, 81541
Germany
Phone: +49 89 5159 16934
Email: cyril.margaria@nsn.com
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