Internet DRAFT - draft-jain-bess-p2mp-pw-lsp-ping
draft-jain-bess-p2mp-pw-lsp-ping
BESS Workgroup P. Jain
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track S. Boutros
Expires: September 22, 2016 VMWare, Inc.
S. Aldrin
Google Inc.
March 21, 2016
Definition of P2MP PW TLV for LSP-Ping Mechanisms
draft-jain-bess-p2mp-pw-lsp-ping-03
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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This Internet-Draft will expire on September 22, 2016.
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Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Specification of Requirements . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Identifying a P2MP PW . . . . . . . . . . . . . . . . . . . . 3
4.1. P2MP Pseudowire Sub-TLV . . . . . . . . . . . . . . . . . 3
5. Encapsulation of OAM Ping Packets . . . . . . . . . . . . . . 4
6. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 4
7. Controlling Echo Responses . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 6
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
11.1. Normative References . . . . . . . . . . . . . . . . . . 6
11.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 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
[RFC7338]. P2MP PWs are carried over P2MP MPLS LSP. The Procedures
for P2MP PW signaling using BGP are described in [RFC7117] and LDP
for single segment P2MP PWs are described in [I-D.ietf-pwe3-p2mp-pw].
Many P2MP PWs can share the same P2MP MPLS LSP and this arrangement
is called Aggregate P-tree. The aggregate P2MP trees require an
upstream assigned label 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 for carrying multicast traffic. In a
Selective P-Tree arrangement, traffic to each multicast group in a
VPN or VPLS instance is carried by a separate unique P-tree. In
Aggregate Selective P-tree arrangement, traffic to a set of multicast
groups from different VPN or VPLS instances is carried over a same
shared P-tree.
The P2MP MPLS LSP are setup either using P2MP RSVP-TE [RFC4875] or
Multipoint LDP (mDLP) [RFC6388]. Mechanisms for fault detection and
isolation for data plane failures for P2MP MPLS LSPs are specified in
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[RFC6425]. This document describes a mechanism to detect data plane
failures for P2MP PW carried over P2MP MPLS LSPs.
This document defines a new P2MP Pseudowire sub-TLV for Target FEC
Stack for P2MP PW. The P2MP 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.
Multi-segment Pseudowires support is out of scope of this document at
present and may be included in future.
2. Specification of Requirements
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. 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,
P2MP Pseudowire sub-TLV, to identify the P2MP PW under test at the
P2MP LSP Tail/Bud node.
4.1. P2MP Pseudowire Sub-TLV
The P2MP Pseudowire sub-TLV has the format shown in Figure 1. This
TLV is included in the echo request sent over P2MP PW by the
originator of request.
The Attachment Group Identifier (AGI) in P2MP Pseudowire Sub-TLV as
described in Section 3.4.2 in [RFC4446], identifies the VPLS
instance. The Originating Router's IP address is the IPv4 or IPv6
address of the P2MP PW root.
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AGI Type | AGI Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
~ AGI Value ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IP Addr Len | |
+-+-+-+-+-+-+-+ |
~ Originating Routers IP Addr ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: P2MP Pseudowire sub-TLV format
For Inclusive and Selective P2MP MPLS P-trees, the echo request is
sent using the P2MP MPLS LSP label.
For Aggregate Inclusive and Aggregate Selective P-trees, the echo
request is 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. Encapsulation of OAM Ping Packets
The LSP Ping Echo request IPv4/UDP packets will be encapsulated with
the MPLS label stack as described in previous sections, followed by
the GAL Label [RFC6426]. The GAL label will be followed by the ACH
with the Pseudowire Associated Channel Type 16 bit value in the ACH
set to IPv4 indicating that the carried packet is an IPv4 packet.
6. 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 P2MP Pseudowire sub-TLV in the echo request
packet. For an Inclusive P2MP P-tree arrangement, the echo request
packet is sent over the P2MP MPLS LSP with {P2MP P-tree label, GAL}
MPLS label stack and IP ACH Channel header. For an Aggregate
Inclusive P-tree arrangement, the echo request packet is sent over
the P2MP MPLS LSP with {P2MP P-tree label, P2MP PW upstream assigned
label, GAL} MPLS label stack and IP ACH Channel header. The
intermediate P router will do swap and replication based on the MPLS
LSP label. Once the echo request packet reaches remote terminating
PEs, T-PE1s will use the GAL label and the IP ACH Channel header to
determine that the packet is IPv4 OAM Packet. The T-PEs will process
the packet and perform checks for the P2MP 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.
7. Controlling Echo Responses
The procedures described in [RFC6425] 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.
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8. Security Considerations
The proposal introduced in this document does not introduce any new
security considerations beyond that already apply to [RFC6425].
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:
o P2MP Pseudowire sub-TLV
10. Acknowledgments
The authors would like to thank Shaleen Saxena, Michael Wildt,
Tomofumi Hayashi, Danny Prairie for their valuable input and
comments.
11. References
11.1. Normative References
[I-D.ietf-pwe3-p2mp-pw]
Sivabalan, S., Boutros, S., and L. Martini, "Signaling
Root-Initiated Point-to-Multipoint Pseudowire using LDP",
draft-ietf-pwe3-p2mp-pw-04 (work in progress), March 2012.
[RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol
Label Switched (MPLS) Data Plane Failures", RFC 4379,
DOI 10.17487/RFC4379, February 2006,
<http://www.rfc-editor.org/info/rfc4379>.
[RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge
Emulation (PWE3)", BCP 116, RFC 4446,
DOI 10.17487/RFC4446, April 2006,
<http://www.rfc-editor.org/info/rfc4446>.
[RFC6425] Saxena, S., Ed., Swallow, G., Ali, Z., Farrel, A.,
Yasukawa, S., and T. Nadeau, "Detecting Data-Plane
Failures in Point-to-Multipoint MPLS - Extensions to LSP
Ping", RFC 6425, DOI 10.17487/RFC6425, November 2011,
<http://www.rfc-editor.org/info/rfc6425>.
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[RFC6426] Gray, E., Bahadur, N., Boutros, S., and R. Aggarwal, "MPLS
On-Demand Connectivity Verification and Route Tracing",
RFC 6426, DOI 10.17487/RFC6426, November 2011,
<http://www.rfc-editor.org/info/rfc6426>.
[RFC7117] Aggarwal, R., Ed., Kamite, Y., Fang, L., Rekhter, Y., and
C. Kodeboniya, "Multicast in Virtual Private LAN Service
(VPLS)", RFC 7117, DOI 10.17487/RFC7117, February 2014,
<http://www.rfc-editor.org/info/rfc7117>.
11.2. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC4875] Aggarwal, R., Ed., Papadimitriou, D., Ed., and S.
Yasukawa, Ed., "Extensions to Resource Reservation
Protocol - Traffic Engineering (RSVP-TE) for Point-to-
Multipoint TE Label Switched Paths (LSPs)", RFC 4875,
DOI 10.17487/RFC4875, May 2007,
<http://www.rfc-editor.org/info/rfc4875>.
[RFC5085] Nadeau, T., Ed. and C. Pignataro, Ed., "Pseudowire Virtual
Circuit Connectivity Verification (VCCV): A Control
Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085,
December 2007, <http://www.rfc-editor.org/info/rfc5085>.
[RFC6388] Wijnands, IJ., Ed., Minei, I., Ed., Kompella, K., and B.
Thomas, "Label Distribution Protocol Extensions for Point-
to-Multipoint and Multipoint-to-Multipoint Label Switched
Paths", RFC 6388, DOI 10.17487/RFC6388, November 2011,
<http://www.rfc-editor.org/info/rfc6388>.
[RFC7338] Jounay, F., Ed., Kamite, Y., Ed., Heron, G., and M. Bocci,
"Requirements and Framework for Point-to-Multipoint
Pseudowires over MPLS Packet Switched Networks", RFC 7338,
DOI 10.17487/RFC7338, September 2014,
<http://www.rfc-editor.org/info/rfc7338>.
Authors' Addresses
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Parag Jain
Cisco Systems, Inc.
2000 Innovation Drive
Kanata, ON K2K-3E8
Canada
Email: paragj@cisco.com
Sami Boutros
VMWare, Inc.
USA
Email: sboutros@vmware.com
Sam Aldrin
Google Inc.
USA
Email: aldrin.ietf@gmail.com
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