Internet DRAFT - draft-ietf-pals-p2mp-pw-lsp-ping
draft-ietf-pals-p2mp-pw-lsp-ping
PALS Workgroup P. Jain, Ed.
Internet-Draft Cisco Systems, Inc.
Intended status: Standards Track S. Boutros
Expires: February 22, 2018 VMWare, Inc.
S. Aldrin
Google Inc.
August 21, 2017
Definition of P2MP PW TLV for LSP-Ping Mechanisms
draft-ietf-pals-p2mp-pw-lsp-ping-05
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
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 February 22, 2018.
Copyright Notice
Copyright (c) 2017 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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include Simplified BSD License text as described in Section 4.e of
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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 . . . . . . . . . . . . . . . . . . . . 4
4.1. P2MP Pseudowire Sub-TLV . . . . . . . . . . . . . . . . . 4
5. Encapsulation of OAM Ping Packets . . . . . . . . . . . . . . 5
6. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Controlling Echo Responses . . . . . . . . . . . . . . . . . 7
8. Security Considerations . . . . . . . . . . . . . . . . . . . 7
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
11.1. Normative References . . . . . . . . . . . . . . . . . . 7
11.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
A Point-to-Multipoint (P2MP) Pseudowire (PW) emulates the essential
attributes of a unidirectional P2MP Telecommunications service such
as P2MP ATM over Public Switched Network (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-pals-p2mp-pw]. Many P2MP PWs can share the
same P2MP MPLS LSP and this arrangement is called Aggregate P2MP
Tree. An aggregate P2MP tree requires an upstream assigned label so
that on the Leaf PE (L-PE), the traffic can be associated with a
Virtual Private Network (VPN) or a Virtual Private LAN Service (VPLS)
instance. When a P2MP MPLS LSP carries only one VPN or VPLS service
instance, the arrangement is called Inclusive P2MP Tree. For
Inclusive P2MP Tree, 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 P2MP Tree arrangement for
carrying multicast traffic. In a Selective P2MP Tree arrangement,
traffic to each multicast group in a VPN or VPLS instance is carried
by a separate unique P2MP LSP. In Aggregate Selective P2MP Tree
arrangement, traffic to a set of multicast groups from different VPN
or VPLS instances is carried over the same shared P2MP LSP.
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 at Root PE(R-PE)
to inform the receiver at Leaf PE(L-PE) of the P2MP PW being tested.
Multi-segment Pseudowires support is out of scope of this document.
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
ACH: Associated Channel Header
AGI: Attachment Group Identifier
ATM: Asynchronous Transfer Mode
CE: Customer Edge
FEC: Forwarding Equivalence Class
GAL: Generic Associated Channel Label
LDP: Label Distribution Protocol
L-PE: Leaf-PE, one of many destinations of the P2MP MPLS LSP i.e.
egress PE
LSP: Label Switched Path
LSR: Label Switching Router
mLDP: Multipoint LDP
MPLS-OAM: MPLS Operations, Administration and Maintenance
P2MP: Point-to-Multipoint
P2MP-PW: Point-to-Multipoint PseudoWire
PE: Provider Edge
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PSN: Public Switched Network
PW: PseudoWire
R-PE: Root PE - ingress PE, PE initiating P2MP PW setup
RSVP: Resource Reservation Protocol
TE: Traffic Engineering
TLV: Type Length Value
VPLS: Virtual Private LAN Service
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 Leaf PE (L-PE).
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. The address family of the IP address is
determined by the IP Addr Len field.
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
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For Inclusive and Selective P2MP Trees, the echo request is sent
using the P2MP MPLS LSP label.
For Aggregate Inclusive and Aggregate Selective P2MP Trees, the echo
request is sent using a label stack of [P2MP MPLS LSP label, upstream
assigned P2MP PW label]. The P2MP MPLS LSP 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 packet is encapsulated with the MPLS label
stack as described in previous sections, followed by one of the two
encapsulation options:
o GAL Label [RFC6426] followed by IPv4(0x0021) or IPv6(0x0057) type
Associated Channel Header (ACH) [RFC4385]
o PW ACH [RFC4385]
To ensure interoperability, implementations of this document MUST
support both encapsulations.
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 Root PE R-PE1, to Leaf
PEs (L-PE2, L-PE3 and L-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 |=========|L-PE2 |AC3 | +---+
| | | | .......PW1.........>|-------->|CE3|
| |R-PE1|=========| . |=========| | | +---+
| | .......PW1........ | +------+ |
| | . |=========| . | +------+ |
| | . | | . |=========|L-PE3 |AC4 | +---+
+---+ |AC1 | . | | .......PW1.........>|-------->|CE4|
|CE1|------->|... | | |=========| | | +---+
+---+ | | . | +------+ +------+ |
| | . | +------+ +------+ |
| | . |=========| P2 |=========|L-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 from Root PE R-PE1,
with the Target FEC Stack TLV containing P2MP Pseudowire sub-TLV in
the echo request packet. For an Inclusive P2MP Tree arrangement, the
echo request packet is sent over the P2MP MPLS LSP with one of the
following two encapsulation options:
o {P2MP LSP label, GAL} MPLS label stack and IPv4 or IPv6 ACH.
o {P2MP LSP label} MPLS label stack and PW ACH.
For an Aggregate Inclusive Tree arrangement, the echo request packet
is sent over the P2MP MPLS LSP with one of the following two
encapsulation options:
o {P2MP LSP label, P2MP PW upstream assigned label, GAL} MPLS label
stack and IPv4 or IPv6 ACH.
o {P2MP LSP label, P2MP PW upstream assigned label} MPLS label stack
and PW ACH.
The intermediate P routers do mpls label swap and replication based
on the incoming MPLS LSP label. Once the echo request packet reaches
L-PEs, L-PEs use GAL label and the IPv4/IPv6 ACH Channel header or PW
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ACH as the case may be, to determine that the packet is an OAM
Packet. The L-PEs 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 [RFC8029] and respond according to [RFC8029]
processing rules.
7. Controlling Echo Responses
The procedures described in [RFC6425] for preventing congestion of
Echo Responses (Echo Jitter TLV in Section 3.3 of [RFC6425]) and
limiting the echo reply to a single L-PE (Node Address P2MP Responder
Identifier TLV in Section 3.2 [RFC6425]) should be applied to P2MP PW
LSP Ping.
8. Security Considerations
The proposal introduced in this document does not introduce any new
security considerations beyond those 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) [RFC8029] 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, Greg Mirsky, Andrew
G. Malis, and Danny Prairie for their valuable input and comments.
11. References
11.1. Normative References
[I-D.ietf-pals-p2mp-pw]
Boutros, S. and S. Sivabalan, "Signaling Root-Initiated
Point-to-Multipoint Pseudowire using LDP", draft-ietf-
pals-p2mp-pw-03 (work in progress), June 2017.
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[RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson,
"Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for
Use over an MPLS PSN", RFC 4385, DOI 10.17487/RFC4385,
February 2006, <https://www.rfc-editor.org/info/rfc4385>.
[RFC4446] Martini, L., "IANA Allocations for Pseudowire Edge to Edge
Emulation (PWE3)", BCP 116, RFC 4446,
DOI 10.17487/RFC4446, April 2006, <https://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,
<https://www.rfc-editor.org/info/rfc6425>.
[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,
<https://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,
<https://www.rfc-editor.org/info/rfc7117>.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029,
DOI 10.17487/RFC8029, March 2017, <https://www.rfc-
editor.org/info/rfc8029>.
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, <https://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, <https://www.rfc-
editor.org/info/rfc4875>.
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[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,
<https://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, <https://www.rfc-
editor.org/info/rfc7338>.
Authors' Addresses
Parag Jain (editor)
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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