MPLS Working Group F. Zhang
Internet-Draft ZTE Corporation
Intended status: Standards Track September 16, 2011
Expires: March 19, 2012
RSVP-TE Extentions to Exchange MPLS-TP Tunnel Numbers
draft-zhang-ccamp-mpls-tp-rsvpte-ext-tunnel-num-00
Abstract
The MPLS Transport Profile (MPLS-TP) identifiers document
[I-D.ietf-mpls-tp-identifiers] introduce two tunnel numbers, A1-
Tunnel_Num and Z9-Tunnel_Num, which allow a compact format for
Maintenance Entity Point Identifier (MEP_ID). For 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, which means that the two MEP nodes need to pre-store each
other's MEP_IDs.
The specification of setting up co-routed bidirectional LSP is
described in the document [RFC3473], which does not introduce the
locally configured tunnel number on the tunnel endpoint. This
document defines the Connection object to exchange the tunnel
numbers.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on March 19, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
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document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . . 3
3. Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Connection Object . . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Normative references . . . . . . . . . . . . . . . . . . . 6
8.2. Informative References . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6
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Internet-Draft RSVP-TE Extentions for Tunnel-Num September 2011
1. Introduction
The MPLS Transport Profile (MPLS-TP) identifiers document
[I-D.ietf-mpls-tp-identifiers] introduce two tunnel numbers, A1-
Tunnel_Num and Z9-Tunnel_Num, which are locally assigned and allow a
compact format for Maintenance Entity Point Identifier (MEP_ID). For
a co-routed bidirectional LSP, the format of A1-MEP_ID is A1-
Node_ID::A1-Tunnel_Num::LSP_Num, and the format of Z9-MEP_ID is Z9-
Node_ID::Z9-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. Hence, the two MEP nodes must pre-store each other's MEP-
IDs before sending the CV packets.
Although the exchange of MEP_IDs can be accomplished by Network
Management System (NMS) if it is deployed, it is still complex when
the LSPs cross different adiminstration domains, which needs the
cooperation of NMSs. So when the LSPs are set up by control plane,
Resource ReserVation Protocol Traffic Engnieering (RSVP-TE) signaling
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 introduce the
locally configured tunnel number on the tunnel endpoint. This
document defines the Connection object to exchange the tunnel
numbers.
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
MPLS-TP co-routed bidirectional LSPs can be deloyed 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
with Connection object inserted in LSP1's Path message , the
following modes may happend.
Modes 1: L bit is set, and the Z9-Tunnel_Num is designated in the
"Destination Tunnel Num" field. If the Z9 node finds that this
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tunnel number is occupied, or it can not be used because of some
local policies, a PathErr message must be sent with "Unavailable
tunnel number" error. Otherwise, the designated tunnel number must
be adopted, and the Connection object may be inserted in the Resv
message without any change.
Modes 2: L bit is not set, and 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 object must be
inserted in the Resv message without any change; if 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
object that must be inserted in the Resv message.
Each mode has its own pros and cons and how to determine the right
mode for a specific network mainly 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 mode 1. The second mode 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.
4. Connection Object
The format of Connection Object (Class-Num of the form 11bbbbbb with
value = TBA, C-Type = TBA) is as follow:
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(TBA)| C-Type (TBA) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Reserverd | Destination Tunnel Num |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Connection Object
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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.
If the L bit is not set, this field can be empty or filled
by the recommended value.
The Connection object may appear in Path or Resv message, and a
midpoint that does not support this object is required to pass it on
unaltered, as indicated by the C-Num and the rules defined in
[RFC2205].
5. IANA Considerations
TBD.
6. Security Considerations
TBD.
7. Acknowledgement
This document was prepared based on the discussion with George
Swallow, valuable comments and input was also received from
Venkatesan Mahalingam and Muliu Tao.
8. References
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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.
8.2. Informative References
[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.
[I-D.ietf-mpls-tp-identifiers]
Bocci, M., Swallow, G., and E. Gray, "MPLS-TP
Identifiers", draft-ietf-mpls-tp-identifiers-07 (work in
progress), July 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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