One document matched: draft-ietf-pwe3-mpls-transport-02.xml
<?xml version="1.0" encoding="US-ASCII"?>
<!DOCTYPE rfc SYSTEM "rfc2629.dtd">
<?rfc toc="yes"?>
<?rfc tocompact="yes"?>
<?rfc tocdepth="3"?>
<?rfc tocindent="yes"?>
<?rfc symrefs="yes"?>
<?rfc sortrefs="yes"?>
<?rfc comments="yes"?>
<?rfc inline="yes"?>
<?rfc compact="yes"?>
<?rfc subcompact="no"?>
<rfc category="info" docName="draft-ietf-pwe3-mpls-transport-02"
ipr="full3978">
<front>
<title abbrev="Appln of Ethernet PW to MPLS Xport Netwks">Application of
Ethernet Pseudowires to MPLS Transport Networks</title>
<author fullname="Stewart Bryant" initials="S Bryant" role="editor"
surname="Bryant">
<organization>Cisco Systems</organization>
<address>
<postal>
<street>250, Longwater, Green Park,</street>
<city>Reading</city>
<code>RG2 6GB, UK</code>
<country>UK</country>
</postal>
<email>stbryant@cisco.com</email>
</address>
</author>
<author fullname="Monique Morrow" initials="M Morrow">
<organization>Cisco Systems</organization>
<address>
<postal>
<street>Glatt-com</street>
<city>CH-8301 Glattzentrum</city>
<country>Switzerland</country>
</postal>
<email>mmorrow@cisco.com</email>
</address>
</author>
<author fullname="George Swallow " initials="G Swallow">
<organization>Cisco Systems</organization>
<address>
<postal>
<street>1414 Massachusetts Ave</street>
<city>Boxborough</city>
<region>MA</region>
<code>01719</code>
</postal>
<email>swallow@cisco.com</email>
</address>
</author>
<author fullname="Rao Cherukuri" initials="R Cherukuri">
<organization>Juniper Networks,</organization>
<address>
<postal>
<street>1194 N. Mathilda Ave</street>
<city>Sunnyvale</city>
<code>CA 94089</code>
</postal>
</address>
</author>
<author fullname="Thomas D. Nadeau" initials="T Nadeau">
<organization>BT</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<country></country>
</postal>
<email>tom.nadeau@bt.com</email>
</address>
</author>
<author fullname="Neil Harrison" initials="N Harrison">
<organization>BT Global Services</organization>
<address>
<postal>
<street>CTO, Network Architecture</street>
</postal>
<email>neil.2.harrison@bt.com</email>
</address>
</author>
<date day="8" month="February" year="2008" />
<area>Internet Area</area>
<workgroup>Network Working Group</workgroup>
<keyword>Sample</keyword>
<keyword>Draft</keyword>
<abstract>
<t>A requirement has been identified by the operator community for the
transparent carriage of the MPLS network of one party over the MPLS
network of another party. This document describes an IETF-recommended
method of satisfying this need using the existing RFC4448 PWE3 Ethernet
pseudowire standard.</t>
</abstract>
<note title="Requirements Language">
<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">RFC2119</xref>.</t>
</note>
</front>
<middle>
<section title="Introduction ">
<t>The operator community has identified the need for the transparent
carriage of the MPLS network of one party over the MPLS network of
another party. This document describes one IETF-recommended mechanism to
satisfy this requirement using the existing <xref
target="RFC4448">RFC4448</xref> PWE3 Ethernet pseudowire standard. The
mechanism described here fulfills the requirements liaised to the IETF
PWE3 working group by the ITU: <eref
target="https://datatracker.ietf.org/public/liaison_detail.cgi?detail_id=286">
-</eref><eref
target="https://datatracker.ietf.org/public/liaison_detail.cgi?detail_id=287">
and </eref>.</t>
<t>The key purpose of this document is to demonstrate that there is an
existing IETF-recommended mechanism that satisfies the requirements
posed by the operator community. It is recognised that it is possible to
design a more efficient method of satisfying the requirement, and the
IETF anticipates that improved solutions will be proposed in the
future.</t>
<t>The architecture required for this mechanism is illustrated in Figure
1 below.</t>
<figure>
<artwork><![CDATA[
+----------------------------------------------------------------+
| |
| IP/MPLS PSN (PHP may be enabled) |
| (client) |
| |
| +---------------------------+ |
| | | |
| | MPLS PSN (No PHP) | |
| | (server) | |
| | | |
| CE1 |PE1 PE2| CE2 |
| +-----+ +-----+ +-----+ +-----+ |
| | | | | | | | | | | | | | | | | |
| | | | +------+ | | | | | | +------+ | | | |
| | | | | 802.3| | | | | | | | 802.3| | | | |
| +-----+ +-----+ +-----+ +-----+ |
| | | | | | | | | |
| | | +-- ---------------------- -+ | | |
+----- --- -------- -- ---------------------- - -------- --- ----+
| | | |<--MPLS LSP (no PHP)->| | | |
| | | | (server) | | | |
| | | | | |
| | |<------------PW----------->| | |
| | | (server) | | |
| | | |
| |<-------------802.3 (Ethernet)-------------->| |
| | (client) | |
| |
|<---------IP/MPLS LSP (PHP may be supported)-------->|
| (client) |
]]></artwork>
<postamble>Figure 1: Application Ethernet over MPLS PW to MPLS
Transport Networks</postamble>
</figure>
<t>An 802.3 (Ethernet) circuit is established between CE1 and CE2. This
circuit may be used for the concurrent transport of MPLS packets as well
as IPv4 and IPv6 packets. The MPLS packets may carry IPv4, IPV6, or
Pseudowire payloads, and Penultimate-Hop-Popping (PHP) may be used. For
clarity these paths are labeled as the client in Figure 1.</t>
<t>An Ethernet pseudowire (PW) is provisioned between PE1 and PE2 and
used to carry the Ethernet from PE1 to PE2. The Ethernet PW is carried
over an MPLS PSN, but this PSN MUST NOT be configured with PHP. For
clarity this Ethernet PW and the MPLS PSN are labeled as the server in
Figure 1. In the remainder of this draft call the server network a
transport network.</t>
</section>
<section title="PWE3 Configuration ">
<t>The PWE3 encapsulation used by this specification to satisfy the
transport requirement is Ethernet <xref target="RFC4448">RFC4448</xref>.
This is used in "raw" mode.</t>
<t>The Control Word MUST be used. The Sequence number MUST be zero.</t>
<t>The use of the Pseudowire Setup and Maintenance Label Distribution
Protocol <xref target="RFC4447">RFC4447</xref> is not required by the
profile of the PWE3 Ethernet pseudowire functionality defined in this
document.</t>
<t>The Pseudowire Label is statically provisioned.</t>
</section>
<section title="OAM ">
<t>Within a connection, traffic units sent from the single source are
constrained to stay within the connection under defect-free conditions.
During misconnected defects, a connection can no longer be assumed to be
constrained and traffic units (and by implication also OAM packets) can
'leak' uni-directionally outside a connection. Therefore during a
misconnected state, it is not possible to rely on OAM which relies on a
request/response mechanism ; and, for this reason such OAM should be
treated with caution if used for diagnostic purposes.</t>
<t>Further, when implementing an ECMP function with MPLS, use of the
label stack as the path selector such that the OAM and data are not in a
co-path as any failure in the data path will note be reflected in the
OAM path. Therefore, an OAM that is carried within the data-path below
the PW label such as VCCV is NOT vulnerable to the above failure mode.
For these reasons the OAM mechanism is <xref
target="RFC5085">RFC5085</xref>, using Bidirectional Forwarding
Detection (BDF) <xref target="I-D.ietf-bfd-base">BFD</xref> for
connection verification (CV). The method of using BFD as a CV method in
VCCV is described in [I-D.draft-ietf-pwe3-vccv-bfd] . One of the VCCV
profiles described in Section 3.1 or Section 3.2 MUST be used. Once a
VCCV is provisioned, and the operational status of the PW is UP, no
other profile SHOULD be used until such time as the PW's operational
status is set to DOWN.</t>
<section title="VCCV profile 1: BFD without IP/UDP Headers">
<t>When PE1 and PE1 are not IP capable or have not been configured
with IP addresses, the following VCCV mechanism SHOULD be used.</t>
<t>The connection verification method used by VCCV is BFD with
diagnostics as defined in [I-D.draft-ietf-pwe3-vccv-bfd].</t>
<t><xref target="RFC5085">RFC5085</xref> specifies that the first
nibble is set to 0x1 to indicate a channel associated with a
pseudowire <xref target="RFC4385">RFC4385</xref>.</t>
<t>The Version and the Reserved fields are set to 0, and the Channel
Type is set to [TBD] to indicate that the payload carried is BFD
without IP/UDP headers, as is defined in
[I-D.draft-ietf-pwe3-vccv-bfd].</t>
</section>
<section title="VCCV profile 2: BFD with IP/UDP Headers">
<t>When PE1 and PE1 are IP capable and have been configured with IP
addresses, the following VCCV mechanism MAY be used.</t>
<t>The connection verification method used by VCCV is BFD with
diagnostics as defined in [I-D.draft-ietf-pwe3-vccv-bfd].</t>
<t><xref target="RFC5085">RFC5085</xref>specifies that the first
nibble is set to 0x1 to indicate a channel associated with a
pseudowire <xref target="RFC4385">RFC4385</xref>.</t>
<t>The Version and the Reserved fields are set to 0, and the Channel
Type is set to 0x21 for IPv4 and 0x56 for IPv6 payloads <xref
target="RFC4446">RFC4446</xref>.</t>
</section>
</section>
<section title="MPLS Layer ">
<t>The architecture of MPLS enabled networks is described in <xref
target="RFC3031">RFC3031</xref> PSN . This section describes a subset of
the functionality of the MPLS enabled PSN. There are two cases that need
to be considered: <list style="numbers">
<t>The case where external configuration is used.</t>
<t>The case where a control plane is available.</t>
</list></t>
<t>Where the use of a control plane is desired this may be based on
GMPLS<xref target="RFC3945"> </xref></t>
<section title="External Configuration ">
<t>The use of external provisioning is not precluded from being
supported by the current MPLS specifications. It is however expicitly
described in this specification to addess the requirements specified
by the ITU <eref
target="https://datatracker.ietf.org/public/liaison_detail.cgi?detail_id=286"></eref>
and <eref
target="https://datatracker.ietf.org/public/liaison_detail.cgi?detail_id=287"></eref>
to address the needs in a transport environment.</t>
<t>The MPLS encapsulation is specified in<xref target="RFC3032">
RFC3032</xref>. All MPLS labels used in the server layer (Figure 1)
MUST be statically provisioned. Labels may be selected from either the
per-platform or the per-interface label space.</t>
<t>All transport LSPs utilized by the PWs described in section 2 MUST
support both unidirectional and bi-directional point-to-point
connections.</t>
<t>The transport LSPs SHOULD support unidirectional
point-to-multipoint connections.</t>
<t>The forward and backward directions of a bi-directional connection
should follow a symmetrically routed (reciprocal) LSP in the server
network.</t>
<t>Equal cost multi-path (ECMP) load balancing MUST NOT be configured
on the transport LSPs utilized by the PWs described in sections 2.</t>
<t>The merging of label switched paths is prohibited and MUST NOT be
configured for the transport LSPs utilized by the PWs described in
section 2.</t>
<t>Penultimate hop popping by the transport LSRs MUST be disabled on
transport LSPs.</t>
<t>Both E-LSP and L-LSP MUST be supported as defined in <xref
target="RFC3270">RFC3270</xref>.</t>
<t>For the MPLS EXP field <xref target="RFC3270">RFC3270</xref> only
the pipe and short-pipe models are supported.</t>
</section>
<section title="Control Plane Configuration ">
<t>In this section we describe the control plane configuration
when<xref target="RFC3209"> RFC3209</xref> “RSVP-TE: Extensions
to RSVP for LSP Tunnels” or the bi-directional support in GMPLS
<xref target="RFC3471">RFC3471 </xref> “Generalized
Multi-Protocol Label Switching (GMPLS) Signaling Functional
Description" and<xref target="RFC3473">RFC3473</xref>
“Generalized Multi-Protocol Label Switching (GMPLS) Signaling
Resource ReserVation Protocol-Traffic Engineering (RSVP-TE)
Extensions” are used to configure the transport MPLS PSN. When
these protocols are used to provide the control plane the following
are automatically provided:</t>
<t><list style="numbers">
<t>There is no label merging unless it is deliberately enabled to
support Fast Re-route (FRR) <xref
target="RFC3209">RFC3209</xref>.</t>
<t>A single path is provided end-to-end (there is no ECMP).</t>
<t>Label switched paths may be unidirectional or bidirectional as
required.</t>
</list></t>
<t>Additionally the following configurations restrictions required to
support external configuration MUST be applied:</t>
<t><list style="symbols">
<t>Penultimate hop popping by the LSRs MUST be disabled on LSPs
providing PWE3 transport network functionality <xref
target="I-D.ali-mpls-rsvp-te-no-php-oob-mapping">NOPHP</xref>.</t>
<t>Both E-LSP and L-LSP MUST be supported as defined in <xref
target="RFC3270">RFC3270</xref>.</t>
<t>The MPLS EXP field is supported according to RFC3270 for only
when the pipe and short-pipe models are utilized.</t>
</list></t>
</section>
</section>
<section title="Congestion Considerations ">
<t>This draft describes a method of using the existing <xref
target="RFC4448">RFC4448</xref> PWE3 Ethernet pseudowire to solve a
particular network application. The congestion considerations associated
with that pseudowire and all subsequent work on congestion
considerations regarding Ethernet pseudowires is applicable to this
draft.</t>
</section>
<section title="Security Considerations">
<t>This draft is a description of the use of existing IETF proposed
standards to solve a network problem, and raises no new security
issues.</t>
<t>The PWE3 security considerations are described in <xref
target="RFC3985">RFC3985</xref><xref target="RFC4448"> and the Ethernet
pseudowire security consoderations RFC4448</xref></t>
<t>The Ethernet pseudowire is transported on an MPLS PSN; therefore, the
security of the pseudowire itself will only be as good as the security
of the MPLS PSN. The server MPLS PSN can be secured by various methods,
as described in <xref target="RFC3031">RFC3031. </xref></t>
<t>The use of static configuration exposes an MPLS PSN to a different
set of security risks to those found in a PSN using dynamic routing. If
a path is missconfigured in a staticly configued network the result can
be a persistent black hole, or much worst, a persistent forwarding loop.
On the otherhand most of the distributed components are less complex.
This is however offset by the need to provide failover and redundancy in
the management and configuration system and the communications paths
between those central systems and the LSRs.</t>
<t>Security achieved by access control of MAC addresses , and the
security of the client layers is out of the scope of this document.</t>
</section>
<section title="IANA Considerations ">
<t>There are no IANA actions required by this draft.</t>
</section>
<section title="Acknowledgements">
<t>The authors wish to thank John Dake, Adrian Farrel, Andy Malis, Ben
Niven-Jenkins, and Yaakov Stein for their review and proposed
enhancements to the text.</t>
</section>
</middle>
<back>
<references title="Normative References">
<?rfc include="reference.RFC.2119"?>
<?rfc include='reference.RFC.3031'?>
<?rfc include='reference.RFC.4448'?>
<?rfc include='reference.RFC.4447'?>
<?rfc include='reference.RFC.4446'?>
<?rfc include='reference.RFC.3032'?>
<?rfc include='reference.RFC.3471'?>
<?rfc include='reference.RFC.3473'?>
<?rfc include='reference.RFC.3270'?>
<?rfc include='reference.RFC.3209'?>
<?rfc include='reference.RFC.4385'?>
<?rfc include='reference.RFC.3945'?>
<?rfc include='reference.RFC.5085'?>
<?rfc include='reference.I-D.ietf-bfd-base'?>
<?rfc include='reference.I-D.ali-mpls-rsvp-te-no-php-oob-mapping'?>
</references>
<references title="Informative References">
<?rfc include='reference.RFC.3985'?>
</references>
</back>
</rfc>| PAFTECH AB 2003-2026 | 2026-04-23 05:46:42 |