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MPLS Working Group F. Zhang
Internet-Draft ZTE Corporation
Intended status: Standards Track November 13, 2011
Expires: May 16, 2012
RSVP-TE Extensions to Exchange MPLS-TP LSP Identifiers
draft-zhang-ccamp-mpls-tp-rsvpte-ext-tunnel-num-01
Abstract
The MPLS Transport Profile (MPLS-TP) identifiers document [RFC6370]
specifies a initial set of identifiers, such as local assigned tunnel
number and Global_ID, which can be used to form Maintenance Entity
Point Identifier (MEP_ID). As to some Operation, Administration and
Maintenance (OAM) functions, such as Connectivity Verification (CV)
[I-D.ietf-mpls-tp-cc-cv-rdi], source MEP_ID must be inserted in the
OAM packets, so that the peer endpoint can compare the received and
expected MEP_IDs to judge whether there is a mismatch [RFC6371],
which means that the two MEP nodes need to pre-store each other's
MEP_IDs.
This document defines the signaling extensions to exchange the Label
Switched Path (LSP) identifiers.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on May 16, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Provisions Relating to IETF Documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . . 3
3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. Co-routed Bidirectional LSP . . . . . . . . . . . . . . . . 3
3.2. Associated Bidirectional LSP . . . . . . . . . . . . . . . 4
4. RSVP-TE Extensions . . . . . . . . . . . . . . . . . . . . . . 5
4.1. LSP Attribute Flags . . . . . . . . . . . . . . . . . . . . 5
4.2. Connection TLV . . . . . . . . . . . . . . . . . . . . . . 5
4.3. Global_ID TLV . . . . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative references . . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
The MPLS Transport Profile (MPLS-TP) identifiers document [RFC6370]
specifies a initial set of identifiers, such as local assigned tunnel
number (Tunnel_Num) and Global_ID, which can be used to form
Maintenance Entity Point Identifier (MEP_ID). The MPLS-TP LSP_MEP_ID
is Node_ID::Tunnel_Num::LSP_Num, and in situations where global
uniqueness is required, this becomes: Global_ID::Node_ID::
Tunnel_Num::LSP_Num. In order to realize some Operation,
Administration and Maintenance (OAM) functions, such as Connectivity
Verification (CV) [I-D.ietf-mpls-tp-cc-cv-rdi], source MEP-ID MUST be
inserted in the OAM packets, in this way the peer endpoint can
compare the received and expected MEP-IDs to judge whether there is a
mismatch [RFC6371]. Hence, the two MEP nodes must pre-store each
other's MEP-IDs before sending the CV packets.
Obviously, the exchange of MEP_IDs can be accomplished by the Network
Management System (NMS), but it is complex when the LSPs cross
different adiminstration domains, which involves the cooperation of
NMSs. When the LSPs are set up by control plane, Resource
ReserVation Protocol Traffic Engnieering (RSVP-TE) messages will be
more suitable to realize the exchange of MEP_IDs.
The specification of setting up co-routed bidirectional LSP is
described in the document [RFC3473], which does not specify the
Global_ID and locally configured Z9-Tunnel_Num. Similary, for
associated bidirectional LSP
[I-D.ietf-ccamp-mpls-tp-rsvpte-ext-associated-lsp], the Global_ID may
also be useful. This document defines the signaling extensions to
exchange the LSP identifiers.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Operation
3.1. Co-routed Bidirectional LSP
MPLS-TP co-routed bidirectional LSPs can be deployed across one or
more administration domains, and NMS may exist in some administration
domains, which knows the tunnel spaces of every node in it's
responsible domain. Consider that LSP1 is initialized at A1 node,
and the "L" bit of the Attributes Flags TLV [RFC5420] may be set in
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the outgoing Path message. If the "L" bit is set, the Connection TLV
MUST be carried and Global_ID TLV is optional in the LSP_ATTRIBUTES
object.
A "L" bit is defined in the Connection TLV. When it is set, the Z9-
Tunnel_Num is designated in the "Destination Tunnel Num" field. If
the Z9 node finds that this tunnel number is occupied, or it can not
be used because of some local policies, an error MUST be generated
"Notify error/ unavailable tunnel number". Otherwise, the designated
tunnel number must be adopted, and the Connection TLV may be inserted
in the Resv message without any change. In case the "L" bit is not
set, a recommended Z9-Tunnel_Num may be filled in the "Destination
Tunnel Num" field. If the Z9 node finds that the recommended value
can be used, the Connection TLV must be inserted in the Resv message
without any change; else the recommended value can not be used or the
"Destination Tunnel Num" field is empty, a new tunnel number will be
allocated and filled into the Connection TLV that must be inserted in
the Resv message. While, that the "L" bit is set or not depends on
the operators' preference. For example, for the operators who are
used to operate traditional transport network and familiar with the
Transport-Centric operational model may prefer "L" bit set. That the
"L" bit is not set is more suitable for the operators who are
familiar with the operation and maintenance of IP/MPLS network, or
the MPLS-TP LSPs cross multiple administration domains.
The Global_ID TLV is needed to be carried if the LSP is across
different administrative domains, which can be inserted in the
outgoing Path message at A1 node or added by the transit Autonomous
System Border Router (ASBR) node that is in the same domain as A1
node, and the value is A1's Global_ID. Z9's Global_ID should be
inserted in the Resv message at Z9 node or any other Label Swithed
Routers (LSRs) that in the same domain as Z9, and the value is Z9's
Global_ID.
3.2. Associated Bidirectional LSP
MPLS-TP associated bidirectional LSPs may also be deployed across one
or more administration domains, and the Global_ID is needed to keep
the MEP_ID globally unique. Consider that the forward LSP is
initialized at A1 node and the backward LSP is initialized at Z9
node, the "L" bit of the Attributes Flags TLV may be set in each
other's outgoing Path messages. When the "L" bit is set, the
Global_ID TLV with the value set to A1/Z9's Global_ID is optional in
the LSP_ATTRIBUTES object and can be inserted in the outgoing Path
message at A1/Z9 node or added by the transit Autonomous System
Border Router (ASBR) node that is in the same domain as A1/Z9 node.
If this TLV is present in Resv message, it can be ignored.
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4. RSVP-TE Extensions
4.1. LSP Attribute Flags
The LSP Attribute Flags TLV is defined in [RFC5420], and this
document introduces a new flag:
One bit ("L", IANA to assign): "LSP identifier indication" is
allocated in the LSP Attributes Flags TLV to be used in the
LSP_ATTRIBUTES object. If the "L" bit is set, it is indicating that
A1/Z9 node needs to know each other's LSP identifer.
4.2. Connection TLV
The Connection TLV is carried in the LSP_ATTRIBUTES object with the
following format:
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 (TBD) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Reserved | Destination Tunnel Num |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Connection TLV
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L
The L bit is set if the initiating node enforces the peer
endpoint to configure the value carried in the field of
"Destination Tunnle Num".
If the bit is not set, the peer endpoint firstly tries to
use the recommended tunnel number; it can use any other
unoccupied tunnnel numbers when the recommended tunnel
number is unavailable.
Reserverd
Must be set to 0 on transmit and ignored on receive.
Destination Tunnel Num
If the L bit is set, it indicates that the peer endpoint
must configure the value carried in this field.
Else the L bit is not set, this field can be empty or filled
by the recommended value.
The Connection TLV may appear in Path or Resv message of co-routed
bidirectional LSP.
4.3. Global_ID TLV
The Global_ID TLV is carried in the LSP_ATTRIBUTES object with the
following format:
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 (TBD) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Global_ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Global_ID TLV
This TLV can be used for co-routed or associated bidirectional LSP.
For co-routed bidirectional LSP, it can appear in Path or Resv
message. As to associated bidirectional LSP, it can only appear in
the Path message, and will be ignored in the Resv message.
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5. IANA Considerations
One bit ("LSP identifier indication") needs to be allocated in the
LSP Attributes Flags Registry.
This document specifies two new TLVs to be carried in the
LSP_ATTRIBUTES objects in Path and Resv messages: the Connection TLV
and Global_ID TLV.
For the existing error code "Notify error" (value 25), one new Error
value: "Unavailable tunnel number" needs to be assigned.
6. Security Considerations
This document adds a new flag to the Attributes Flags TLV and
introduce two new TLVs in the LSP_ATTRIBUTES objects. It does not
introduce any new direct security issues, and the reader is referred
to the security considerations expressed in [RFC2205] and [RFC5420].
For a more comprehensive discussion on GMPLS security please see the
Security Framework for MPLS and GMPLS Networks [RFC5920].
7. Acknowledgement
This document was prepared based on the discussion with George
Swallow, valuable comments and input were also received from Berger
Lou, Venkatesan Mahalingam, Jaihari Kalijanakiraman and Muliu Tao.
8. References
8.1. Normative references
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC5420] Farrel, A., Papadimitriou, D., Vasseur, JP., and A.
Ayyangarps, "Encoding of Attributes for MPLS LSP
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Establishment Using Resource Reservation Protocol Traffic
Engineering (RSVP-TE)", RFC 5420, February 2009.
8.2. Informative References
[I-D.ietf-ccamp-mpls-tp-rsvpte-ext-associated-lsp]
Zhang, F. and R. Jing, "RSVP-TE Extensions for Associated
Bidirectional LSPs",
draft-ietf-ccamp-mpls-tp-rsvpte-ext-associated-lsp-02
(work in progress), October 2011.
[I-D.ietf-mpls-tp-cc-cv-rdi]
Allan, D., Swallow, G., and J. Drake, "Proactive
Connectivity Verification, Continuity Check and Remote
Defect indication for MPLS Transport Profile",
draft-ietf-mpls-tp-cc-cv-rdi-06 (work in progress),
August 2011.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
[RFC6370] Bocci, M., Swallow, G., and E. Gray, "MPLS Transport
Profile (MPLS-TP) Identifiers", RFC 6370, September 2011.
[RFC6371] Busi, I. and D. Allan, "Operations, Administration, and
Maintenance Framework for MPLS-Based Transport Networks",
RFC 6371, September 2011.
Author's Address
Fei Zhang
ZTE Corporation
Email: zhang.fei3@zte.com.cn
Xiao Bao
ZTE Corporation
Email: bao.xiao1@zte.com.cn
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