One document matched: draft-jain-bess-p2mp-pw-lsp-ping-01.xml
<?xml version="1.0" encoding="US-ASCII"?>
<!-- $Id: draft-jain-pals-p2mp-pw-lsp-ping.xml 2014-07-03 paragj $ -->
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]>
<rfc category="std" docName="draft-jain-bess-p2mp-pw-lsp-ping-01"
ipr="trust200902" updates="">
<?rfc toc="yes" ?>
<?rfc compact="yes"?>
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<front>
<title abbrev="P2MP PW LSP Ping">Definition of P2MP PW TLV for LSP-Ping Mechanisms</title>
<author fullname="Parag Jain" initials="P." surname="Jain">
<organization>Cisco Systems, Inc.</organization>
<address>
<postal>
<street>2000 Innovation Drive</street>
<city>Kanata</city>
<code>K2K-3E8</code>
<region>ON</region>
<country>Canada</country>
</postal>
<email>paragj@cisco.com</email>
</address>
</author>
<author fullname="Sami Boutros" initials="S." surname="Boutros">
<organization>Cisco Systems, Inc.</organization>
<address>
<postal>
<street>3750 Cisco Way</street>
<city>San Jose</city>
<code>95134</code>
<region>CA</region>
<country>USA</country>
</postal>
<email>sboutros@cisco.com</email>
</address>
</author>
<author fullname="Sam Aldrin" initials="S." surname="Aldrin">
<organization>Goodle Inc.</organization>
<address>
<postal>
<street></street>
<city></city>
<code></code>
<region></region>
<country>USA</country>
</postal>
<email>aldrin.ietf@gmail.com</email>
</address>
</author>
<date year="2015"/>
<area>Routing</area>
<workgroup>BESS Workgroup</workgroup>
<keyword>P2MP PW</keyword>
<keyword>LSP Ping</keyword>
<keyword>MPLS OAM</keyword>
<abstract>
<t>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.</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>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
<xref target="RFC7338"/>.
P2MP PWs are carried over P2MP MPLS LSP. The Procedures for
P2MP PW signaling using BGP are described in <xref target="RFC7117"/>
and LDP for single segment P2MP PWs are described in
<xref target="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.</t>
<t>The P2MP MPLS LSP are setup either using P2MP RSVP-TE <xref target="RFC4875"/>
or Multipoint LDP (mDLP) <xref target="RFC6388"/>.
Mechanisms for fault detection and isolation for data
plane failures for P2MP MPLS LSPs are specified in [RFC6425]. This
document describes a mechanism to detect data plane failures for
P2MP PW carried over P2MP MPLS LSPs.</t>
<t>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.</t>
<t>Multi-segment Pseudowires support is out of scope of this document
at present and may be included in future. </t>
</section>
<section title="Specification of Requirements">
<t>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 <xref
target="RFC2119"/>.</t>
</section>
<section title="Terminology">
<t>ATM: Asynchronous Transfer Mode</t>
<t>LSR: Label Switching Router</t>
<t>MPLS-OAM: MPLS Operations, Administration and Maintenance</t>
<t>P2MP-PW: Point-to-Multipoint PseudoWire</t>
<t>PW: PseudoWire</t>
<t>TLV: Type Length Value</t>
</section>
<section title="Identifying a P2MP PW">
<t>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.</t>
<section title="P2MP Pseudowire Sub-TLV">
<t>The P2MP 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.</t>
<t>The Attachment Group Identifier (AGI) in P2MP Pseudowire Sub-TLV
as described in Section 3.4.2 in <xref target="RFC4446"/>,
identifies the VPLS instance.
The Originating Router's IP address is the IPv4 or IPv6 address of the
P2MP PW root.</t>
<figure align="left">
<preamble/>
<artwork align="left"><![CDATA[
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
]]></artwork>
</figure>
<t>For Inclusive and Selective P2MP MPLS P-trees, the echo request is
sent using the P2MP MPLS LSP label. </t>
<t>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.</t>
</section>
</section>
<section title="Operations">
<t>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.</t>
<figure align="left">
<preamble/>
<artwork align="left"><![CDATA[
|<--------------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
]]></artwork>
</figure>
<t>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. 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 inner 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 P2MP Pseudowire sub-TLV present in the Target FEC
Stack TLV as described in Section 4.4 in <xref target="RFC4379"/> and respond
according to <xref target="RFC4379"/> processing rules.</t>
</section>
<section title="Encapsulation of OAM Ping Packets">
<t>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 <xref target="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.</t>
</section>
<section title="Controlling Echo Responses ">
<t>The procedures described in <xref target="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.</t>
</section>
<section title="Security Considerations">
<t>The proposal introduced in this document does not introduce any new
security considerations beyond that already apply to [RFC6425].</t>
</section>
<section title="IANA Considerations">
<t>This document defines a new sub-TLV type to be included in Target
FEC Stack TLV (TLV Type 1) [RFC4379] in LSP Ping.</t>
<t>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: </t>
<t><list style="symbols">
<t>P2MP Pseudowire sub-TLV</t>
</list></t>
</section>
<section title="Acknowledgments">
<t>The authors would like to thank Shaleen Saxena, Michael Wildt,
Tomofumi Hayashi, Danny Prairie for their valuable input and
comments.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include="reference.RFC.4379"?>
<?rfc include="reference.RFC.7117"?>
<?rfc include="reference.I-D.ietf-pwe3-p2mp-pw"?>
<?rfc include="reference.RFC.6425"?>
<?rfc include="reference.RFC.6426"?>
<?rfc include="reference.RFC.4446"?>
</references>
<references title="Informative References">
<?rfc include="reference.RFC.2119"?>
<?rfc include="reference.RFC.5085"?>
<?rfc include="reference.RFC.6388"?>
<?rfc include="reference.RFC.4875"?>
<?rfc include="reference.RFC.7338"?>
</references>
</back>
</rfc>
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