One document matched: draft-zhang-ccamp-srlg-fa-configuration-02.txt
Differences from draft-zhang-ccamp-srlg-fa-configuration-01.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: September 11, 2011 March 11, 2011
RSVP-TE Extensions for Configuration SRLG of an FA
draft-zhang-ccamp-srlg-fa-configuration-02.txt
Status of this Memo
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This Internet-Draft will expire on September 11, 2011.
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Abstract
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 Flag....................................4
3.2. SRLG sub-object.........................................5
3.3. Signaling Procedures....................................6
4. Manageability Considerations.................................6
5. IANA Considerations..........................................7
5.1. RSVP Attribute Bit Flags................................7
5.2. ROUTE_RECORD Object.....................................7
6. Security Considerations......................................7
7. References...................................................7
1. Introduction
As described in [RFC4206], H-LSP (Hierarchical LSP) can be used for
carrying one or more other LSPs. [RFC6107] 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 [RFC6107], 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.
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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
[RFC6107], 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
[RFC6107].
In addition, Section 1.2 of [RFC6107] 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
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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-
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 Flag
In order to indicate nodes that SRLG collection is desired, a new
flag in the Attribute Flags TLV which can be carried in an
LSP_REQUIRED_ATTRIBUTES Object is needed:
SRLG Collection flag (to be assigned by IANA, recommended bit zero)
The SRLG Collection flag is meaningful on a Path message. If the SRLG
Collection flag is set to 1, it means that the SRLG information
should be reported to the head and tail node along the setup of the
LSP.
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The rules of the processing of the Attribute Flags TLV are not
changed.
3.2. SRLG sub-object
A new SRLG sub-object is defined for RRO(ROUTE_RECORD Object) to
record the SRLG information of the LSP. Its format is modeled on the
RRO sub-objects defined in [RFC3209].
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRLG ID 1 (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ...... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRLG ID n (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type
The type of the sub-object, to be assigned by IANA, which is
recommended 34.
Length
The Length contains the total length of the sub-object in
bytes, including the Type and Length fields. The Length
depends on the number of SRLG IDs.
SRLG Id
The 32-bit identifier of the SRLG.
Reserved
This field is reserved. It SHOULD be set to zero on
transmission and MUST be ignored on receipt.
The rules of the processing of the LSP_REQUIRED_ATTRIBUTES Object and
ROUTE_RECORD Object are not changed.
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3.3. Signaling Procedures
Typically, the head node gets the route information of an LSP by
adding a RRO which contains the sender's IP addresses in the Path
message. If a head node also desires SRLG recording, it sets the SRLG
Collection Flag in the Attribute Flags TLV which can be carried in an
LSP_REQUIRED_ATTRIBUTES Object.
When a node receives a Path message which carries an
LSP_REQUIRED_ATTRIBUTES Object and the SRLG Collection Flag is set,
if local policy determines that the SRLG information should not be
provided to the endpoints, it must return a PathErr message to reject
the Path message. Otherwise, it must add an SRLG sub-object to the
RRO to carry the local SRLG information. Then it forwards the Path
message to the next node in the downstream direction.
Following the steps described above, the intermediate nodes of the
LSP can collect the SRLG information in the RRO during the forwarding
of the Path message hop by hop. When the Path message arrives at the
tail node, the tail node can get the SRLG information from the RRO.
Before the Resv message is sent to the upstream node, the tail node
adds an SRLG sub-object to the RRO. The collected SRLG information
can be carried in the SRLG sub-object. Therefore, during the
forwarding of the Resv message in the upstream direction, the SRLG
information is not needed to be collected hop by hop.
Based on the above procedure, the endpoints can get the SRLG
information automatically. Then the endpoints can for instance
advertise it as a TE link to the routing instance based on the
procedure described in [RFC6107] and configure the SRLG information
of the FA automatically.
It is noted that a node (e.g. the edge node of a domain) may edit the
RRO to remove the route information (e.g. node, interface identifier
information) before forwarding it due to some reasons (e.g.
confidentiality or reduce the size of RRO), but the SRLG information
should be retained if it is desirable for the endpoints of the LSP.
4. Manageability Considerations
TBD.
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5. IANA Considerations
5.1. RSVP Attribute Bit Flags
The IANA has created a registry and manages the space of attributes
bit flags of Attribute Flags TLV as described in section 11.3 of
[RFC5420]. It is requested that the IANA makes assignments from the
Attribute Bit Flags.
This document introduces a new Attribute Bit Flag:
- Bit number: TBD (0)
- Defining RFC: this I-D
- Name of bit: SRLG Collection Flag
- The meaning of the Attribute Flags TLV on a Path is defined in
this I-D
5.2. ROUTE_RECORD Object
IANA has made the following assignments in the "Class Names, Class
Numbers, and Class Types" section of the "RSVP PARAMETERS" registry
located at http://www.iana.org/assignments/rsvp-parameters. We
request that IANA make assignments from the ROUTE_RECORD [RFC3209]
portions of this registry.
This document introduces a new RRO sub-object:
Type Name Reference
--------- ---------------------- ---------
TBD (34) SRLG sub-object This I-D
6. Security Considerations
TBD.
7. References
[RFC3477] K. Kompella, Y. Rekhter, " Signalling Unnumbered Links in
Resource ReSerVation Protocol - Traffic Engineering (RSVP-
TE) ", rfc3477, January 2003.
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[RFC4206] K. Kompella, Y. Rekhter, " Label Switched Paths (LSP)
Hierarchy with Generalized Multi-Protocol Label Switching
(GMPLS) Traffic Engineering (TE) ", rfc4206, October 2005.
[RFC4208] G. Swallow, J. Drake, Boeing, H. Ishimatsu, and Y. Rekhter,
"Generalized Multiprotocol Label Switching (GMPLS) User-
Network Interface (UNI): Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Support for the Overlay
Model", RFC 4208, October 2005.
[RFC4874] CY. Lee, A. Farrel, S. De Cnodder, " Exclude Routes -
Extension to Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) ", rfc4874, April 2007.
[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.
[RFC5420] A. Farrel, D. Papadimitriou, J.P, and A. Ayyangar,
"Encoding of Attributes for MPLS LSP Establishment Using
Resource Reservation Protocol Traffic Engineering (RSVP-
TE)", RFC 5420, February 2009.
[RFC6107] K. Shiomoto, A. Farrel, " Procedures for Dynamically
Signaled Hierarchical Label Switched Paths ", draft-ietf-
ccamp-lsp-hierarchy-bis-08, August 2010.
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
Xiaobing Zi
Huawei Technologies
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzhen 518129 P.R.China
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Phone: +86-755-28973229
Email: zixiaobing@huawei.com
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