One document matched: draft-jain-mpls-p2mp-pw-lsp-ping-00.txt
Network Working Group Parag Jain, Ed.
Internet Draft Sami Boutros
Intended status: Standards Track Cisco Systems, Inc.
Expires: December 28, 2011
June 28, 2011
Definition of P2MP PW TLV for LSP-Ping Mechanisms
draft-jain-mpls-p2mp-pw-lsp-ping-00.txt
Abstract
LSP-Ping is a widely deployed Operation, Administration, and
Maintenance (OAM) mechanism in MPLS networks. This document
describes a mechanism to verify connectivity of Point-to-Multipoint
(P2MP) Pseudowires (PW) using LSP Ping.
Status of this Memo
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Table of Contents
1. Introduction 2
2. Conventions used in this document 3
3. Terminology 3
4. Identifying a P2MP PW 3
4.1. FEC 130 Pseudowire Sub-TLV 3
5. Operations 4
6. Reply Mode Field 5
7. Controlling Echo Responses 6
8. Security Considerations 6
9. IANA Considerations 6
10. References 6
10.1. Normative References 6
10.2. Informative References 6
11. Acknowledgments 7
1. Introduction
A Point-to-Multipoint (P2MP) Pseudowire (PW) emulates the essential
attributes of a unidirectional P2MP Telecommunications service such
as P2MP ATM over PSN. Requirements for P2MP PW are described in
[PPWREQ]. The Procedure for P2MP PW signaling using LDP for single
segment P2MP PWs are described in [PPWPWE3]. Many P2MP PWs share the
same P2MP MPLS LSP, the arrangement is called Aggregate P-tree. The
aggregate P2MP trees require an upstream assigned label to be
carried so that on the tail of the P2MP LSP, the traffic can be
associated with a VPN or a VPLS instance. When a P2MP MPLS LSP
carries only one VPN or VPLS service instance the arrangement is
called Inclusive P-Tree. For Inclusive P-Trees, P2MP MPLS LSP label
itself can uniquely identify the VPN or VPLS service being carried
over P2MP MPLS LSP. The P2MP MPLS LSP can also be used in Selective
P-Tree arrangement. Selective P-Trees are out of scope of this
document at present and the draft will be extended to include
selective P-Trees in future.
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P2MP PW service is carried over P2MP MPLS LSP. The P2MP MPLS LSP are
setup either using MLDP [MLDP] or P2MP RSVP-TE [RFC4875]. Mechanisms
for fault detection and isolation for data plane failures for P2MP
MPLS LSPs are specified in [PLSPPING]. This document describes a
mechanism to detect data plane failures for P2MP PW carried over
P2MP MPLS LSPs.
This document defines a new FEC 130 Pseudowire sub-TLV for Target
FEC Stack for P2MP PW. The FEC 130 Pseudowire sub-TLV is added in
Target FEC Stack TLV by the originator of the echo request to inform
the receiver at P2MP MPLS LSP tail, of the P2MP PW being tested.
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 RFC-2119 [RFC2119].
The term "FEC-Type" is used to refer to a tuple consisting of <FEC
Element Type, Address Family>.
3. Terminology
ATM: Asynchronous Transfer Mode
LSR: Label Switching Router
MPLS-OAM: MPLS Operations, Administration and Maintenance
P2MP-PW: Point-to-Multipoint PseudoWire
PW: PseudoWire
TLV: Type Length Value
4. Identifying a P2MP PW
This document introduces a new LSP Ping Target FEC Stack sub-TLV,
FEC 130 Pseudowire sub-TLV, to identify the P2MP PW under test at
the P2MP LSP Tail/Bud node.
4.1. FEC 130 Pseudowire Sub-TLV
The FEC 130 Pseudowire sub-TLV fields are taken from P2MP PW FEC
Element (FEC Type 0x82) defined in [PPWPWE3]. The PW Type is a 15-
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bit number indicating the encapsulation type. It is carried right
justified in the field below PW Type with the high-order bit set to
zero. All the other fields are treated as opaque values and copied
directly from the P2MP FEC Element (FEC Type 0x82) format.
The FEC 130 Pseudowire sub-TLV has the format shown in Figure 1.
This TLV will be included in the echo request sent over P2MP PW by
the originator of request.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| PW Type | AGI Type | AGI Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ AGI Value ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AII Type | SAII Length | SAII Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ SAII Value (continued) ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: FEC 130 Pseudowire sub-TLV format
For Inclusive P2MP MPLS P-trees, the echo request will be sent using
the P2MP MPLS LSP label.
For Aggregate Inclusive P-trees, the echo request will be sent using
a label stack of <P2MP MPLS P-tree label, upstream assigned P2MP PW
label>. The P2MP MPLS P-tree label is the outer label and upstream
assigned P2MP PW label is inner label.
5. Operations
In this section, we explain the operation of the LSP Ping over P2MP
PW. Figure 2 shows a P2MP PW PW1 setup from T-PE1 to remote PEs (T-
PE2, T-PE3 and T-PE4). The transport LSP associated with the P2MP PW1
can be MLDP P2MP MPLS LSP or P2MP TE tunnel.
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|<--------------P2MP PW---------------->|
Native | | Native
Service | |<--PSN1->| |<--PSN2->| | Service
(AC) V V V V V V (AC)
| +-----+ +------+ +------+ |
| | | | P1 |=========|T-PE2 |AC3 | +---+
| | | | .......PW1.........>|-------->|CE3|
| |T-PE1|=========| . |=========| | | +---+
| | .......PW1........ | +------+ |
| | . |=========| . | +------+ |
| | . | | . |=========|T-PE3 |AC4 | +---+
+---+ |AC1 | . | | .......PW1.........>|-------->|CE4|
|CE1|------->|... | | |=========| | | +---+
+---+ | | . | +------+ +------+ |
| | . | +------+ +------+ |
| | . |=========| P2 |=========|T-PE4 |AC5 | +---+
| | .......PW1..............PW1.........>|-------->|CE5|
| | |=========| |=========| | | +---+
| +-----+ +------+ +------+ |
Figure 2: P2MP PW
When an operator wants to perform a connectivity check for the P2MP
PW1, the operator initiate a LSP-Ping request with the Target FEC
Stack TLV containing FEC 130 Pseudowire sub-TLV in the echo request
packet. The echo request packet is sent over the P2MP MPLS LSP using
the P2MP MPLS LSP label for Inclusive P-tree or with a label stack
with Upstream assigned P2MP PW label as bottom label and P2MP MPLS
LSP label as the top label. The intermediate P router will do swap
and replication based on the mpls LSP label. Once the packet reaches
remote terminating PEs, the T-PEs will process the packet and perform
checks for the FEC 130 Pseudowire sub-TLV present in the Target FEC
Stack TLV as described in Section 4.4 in [RFC4379] and respond
according to [RFC4379] processing rules.
6. Reply Mode Field
Since P2MP PWs are unidirectional, Reply Mode value of 4 "Reply via
application level control channel" should not be used in Reply Mode
field described in Section 3 in [RFC4379] in echo request message
for P2MP PWs.
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7. Controlling Echo Responses
The procedures described in [PLSPPING] for preventing congestion of
Echo Responses (Echo Jitter TLV) and limiting the echo reply to a
single egress node (Node Address P2MP Responder Identifier TLV) can
be applied to P2MP PW LSP Ping.
8. Security Considerations
The proposal introduced in this document does not introduce any new
security considerations beyond that already apply to [PLSPPING].
9. IANA Considerations
This document defines a new sub-TLV type to be included in Target
FEC Stack TLV (TLV Type 1) [RFC4379] in LSP Ping.
IANA is requested to assign a sub-TLV type value to the following
sub-TLV from the "Multiprotocol Label Switching (MPLS) Label
Switched Paths (LSPs) Parameters - TLVs" registry, "TLVs and sub-
TLVs" sub-registry.
FEC 130 Pseudowire sub-TLV (See Section 3). Suggested value 24.
10. References
10.1. Normative References
[RFC4379] K. Kompella, G. Swallow, "Detecting Multi-Protocol Label
Switched (MPLS) Data Plane Failures", RFC 4379, February
2006.
[PPWPWE3] Martini, L. et. al, "Signaling Root-Initiated Point-to-
Multipoint Pseudowires using LDP", draft-ietf-pwe3-p2mp-
pw-02.txt, Work in Progress, March 2011.
[PLSPPING]Saxena, S et. Al, "Detecting Data Plane Failures in Point-
to-Multipoint Multiprotocol Label Switching (MPLS) -
Extensions to LSP". draft-ietf-mpls-p2mp-lsp-ping-17, Work
in Progress, June 2011
10.2. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC2119, March 1997.
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[RFC5085] T. Nadeau, et. al, "Pseudowire Virtual Circuit
Connectivity Verification (VCCV): A Control Channel for
Pseudowires ", RFC 5085, December 2007.
[MLDP] Minei, I., Kompella, K., Wijnands, I., and Thomas, B.,
"LDP Extensions for Point-to-Multipoint and Multipoint-to-
Multipoint Label Switched Paths", draft-ietf-mpls-ldp-p2mp
-10.txt, Work in Progress, July 2010.
[RFC4875] Aggarwal, R., Papadimitriou, D., and Yasukawa, S.,
"Extensions to Resource Reservation Protocol - Traffic
Engineering (RSVP-TE) for Point-to-Multipoint TE Label
Switched Paths (LSPs)", RFC 4875, May 2007.
[PPWREQ] F. Jounay, et. al, "Requirements for Point to Multipoint
Pseudowire", draft-ietf-pwe3-p2mp-pw-requirements-
03.txt, Work in Progress, August 2010.
11. Acknowledgments
The authors would like to thank Shaleen Saxena, Michael Wildt,
Tomofumi Hayashi, Danny Prairie for their valuable input and
comments.
This document was prepared using 2-Word-v2.0.template.dot.
Authors' Addresses
Parag Jain
Cisco Systems, Inc.,
2000 Innovation Drive,
Kanata, ON K2K3E8, Canada.
E-mail: paragj@cisco.com
Sami Boutros
Cisco Systems, Inc.
3750 Cisco Way,
San Jose, CA 95134, USA.
E-mail: sboutros@cisco.com
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