One document matched: draft-bellagamba-ccamp-rsvp-te-mpls-tp-oam-ext-00.xml
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<rfc category="exp" docName="draft-bellagamba-ccamp-rsvp-te-mpls-tp-oam-ext-00"
ipr="trust200902">
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<!-- ***** FRONT MATTER ***** -->
<front>
<!-- The abbreviated title is used in the page header - it is only necessary if the
full title is longer than 39 characters -->
<title abbrev="RSVP-TE Ext for MPLS-TP OAM Config">RSVP-TE Extensions for
MPLS-TP OAM Configuration</title>
<!-- add 'role="editor"' below for the editors if appropriate -->
<!-- Another author who claims to be an editor -->
<author fullname="Elisa Bellagamba" initials="E.B." role="editor"
surname="Bellagamba">
<organization>Ericsson</organization>
<address>
<postal>
<street>Farogatan 6</street>
<!-- Reorder these if your country does things differently -->
<city>Stockholm</city>
<region></region>
<code>164 40</code>
<country>Sweden</country>
</postal>
<phone>+46 761440785</phone>
<email>elisa.bellagamba@ericsson.com</email>
<!-- uri and facsimile elements may also be added -->
</address>
</author>
<author fullname="Loa Andersson" initials="L.A." role="editor"
surname="Andersson">
<organization>Ericsson</organization>
<address>
<postal>
<street>Farogatan 6</street>
<!-- Reorder these if your country does things differently -->
<city>Stockholm</city>
<region></region>
<code>164 40</code>
<country>Sweden</country>
</postal>
<phone></phone>
<email>loa.andersson@ericsson.com</email>
<!-- uri and facsimile elements may also be added -->
</address>
</author>
<author fullname="Pontus Skoldstrom" initials="P.S." role=""
surname="Skoldstrom">
<organization>Acreo</organization>
<address>
<postal>
<street></street>
<!-- Reorder these if your country does things differently -->
<city>Stockholm</city>
<region></region>
<code>164 40</code>
<country>Sweden</country>
</postal>
<phone></phone>
<email>pontus.skoldstrom@acreo.com</email>
<!-- uri and facsimile elements may also be added -->
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</author>
<!-- If the month and year are both specified and are the current ones, xml2rfc will fill
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<!-- Meta-data Declarations -->
<date day="2" month="July" year="2009" />
<area>Signaling</area>
<workgroup>CCAMP Working Group</workgroup>
<keyword>RSVP-TE</keyword>
<keyword>GMPLS</keyword>
<keyword>MPLS-TP</keyword>
<abstract>
<t>
This document defines a method for the configuration of the
Bidirectional Forwarding Detection (BFD)
OAM mechanism through RSVP-TE Control Plane.
The procedures described are experimental and are intended to be
possibly updated with other proposed OAM tools and BFD future extensions.</t>
</abstract>
</front>
<middle>
<section title="Introduction">
<t>This document defines a method for the configuration of the Bidirectional Forwarding Detection (BFD)
OAM mechanism through GMPLS Control Plane.</t>
<t>The procedures described are experimental and are intended to be possibly updated with
other proposed OAM tools and BFD future extensions.</t>
<t>The document intent is both disseminating experimental results carried out within Ericsson Research
and provide an initial input for further Control Plane extension in CCAMP IETF group.</t>
<section 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">RFC 2119</xref>.
</t>
</section>
<section title="Contributing Authors">
<t>The editors gratefully acknowledge the contributions of Benoit C Tremblay,
Andras Kern, Attila Takacs and David Jocha.</t>
</section>
<section title="Background">
<t>MPLSTransport Profile (MPLS-TP), describes a profile of MPLS that enables
operational models typical in transport networks, while providing additional OAM,
survivability and other maintenance functions not currently supported by MPLS.</t>
<t>[MPLS-TP-OAM-REQ] defines the requirements by which the OAM functionality of
MPLS-TP should abide. The requirements listed may be met by one or more
OAM Protocols.</t>
<t>Bidirectional Forwarding Detection, as described in [BFD],
defines a protocol that provides low-overhead, short-duration detection of
failures in the path between two forwarding engines, including the interfaces,
data link(s), and to the extent possible the forwarding engines themselves.
BFD can be used to track the liveliness of MPLS-TP point-to-point and p2mp
connections and detect data plane failures.
This version of the draft is focused on unidirectional and bidirectional
p2p connection.</t>
<t>There are no OAM mechanisms designated to operate in conjunction with
MPLS-TP yet. BFD meets several of the requirements listed so far in
[MPLS-TP-OAM-REQ] and can be a good candidate for Continuity Check in MPLS-TP.</t>
<t>Other proposed OAM tools and BFD future extensions will be possibly taken
into account in this document during the next releases.</t>
<t>RSVP-TE control plane [RFC3471] has been chosen to support the establishment of
MPLS-TP LSPs.</t>
</section>
</section>
<section title="Overview of BFD OAM operation">
<t>BFD is a simple hello protocol that in many respects is similar to the
detection components of well-known routing protocols. A pair of systems
transmit BFD packets periodically over each path between the two systems,
and if a system stops receiving BFD packets for long enough, some component
in that particular bidirectional path to the neighboring system is assumed to
have failed. Systems may also negotiate to not send periodic BFD packets in
order to reduce overhead.</t>
<t>A path is only declared to be operational when two-way communication
has been established between systems, though this does not preclude the
use of unidirectional links.</t>
<t>Section 3 in [BFD] states that a separate BFD session is created for
each communications path and data protocol in use between two systems.</t>
<t>Each system estimates how quickly it can send and receive BFD packets
in order to come to an agreement with its neighbor about how rapidly
detection of failure will take place. These estimates can be modified in
real time in order to adapt to unusual situations. This design also allows
for fast systems on a shared medium with a slow system to be able to more
rapidly detect failures between the fast systems while allowing the slow system
to participate to the best of its ability.</t>
<t>The ability of each system to control the BFD packet transmission rate
in both directions provides a mechanism for congestion control, particularly
when BFD is used across multiple network hops.</t>
</section>
<section title="RSVP-TE Extensions">
<section title="Operation overview">
<t>A BFD session may be established for a FEC associated with a MPLS LSP. In case of:</t>
<t><list style="symbols">
<t>PHP</t>
<t>when the egress LSR distributes an explicit null label to the penultimate
hop router</t>
<t>next-hop label allocation</t>
</list></t>
<t>the BFD control packet received by the egress LSR does not contain
sufficient information to associate it with a BFD session. Hence the
demultiplexing MUST be done using the remote discriminator field in the
received BFD control packet.</t>
<t>The exchange of BFD discriminators for this purpose can be achieved
with LSP Ping as described in [LSP Ping]. However, LSP Ping presents
some drawbacks such as high computational complexity and the dependency to
the IP protocol, as described in [MPLS-TP OAM Analysis]. Such dependency should
be avoided in a MPLS-TP context, since MPLS-TP can not count on IP as
forwarding mechanism in the data plane.</t>
<t>Below, we define some simple additions that can be done in GMPLS
RSVP-TE in order to carry out a BFD session setup at the same time
as the setup of the LSP related to the BFD session.</t>
<t>With the terms “ingress LSR” and “egress LSR” we will not
refer to any direction in the forwarding plane, but only to the LSR triggering
the LSP setup (ingress LSR) and the one triggering the response to it (egress LSR).</t>
<t>During the LSP signaling, the Control Plane instance in the ingress
and the egress LSR announces the BFD OAM Configuration TLV
(inside the LSP_ATTRIBUTES object carried by the Path and Resv message
respectively), which includes the “Local Discriminator” sub-TLV.
During the BFD session the ingress LSR will use as “MyDiscriminator”
the value announced in the “Local Discriminator”(Path message) and
as “YourDiscriminator” the value received in the “Local
Discriminator” (Resv message).</t>
<t>Moreover, in the BFD protocol, the time values used to determine
BFD packet transmission intervals and the session Detection Time
are continuously negotiated by the BFD protocol itself, and thus may
be changed at any time. The negotiation and time values are independent
in each direction for each session, as described in [BFD] section 6.8.2.</t>
<t>It is introduced the possibility of advertising the initial time values,
together with the Discriminator values, during the control plane session setup.
The Control Plane instance in the ingress LSR will advertise its timing
requirements in the Path messages. It will be signaled a single value for
both directions in asynchronous and echo mode. The egress LSR will acknowledge
them or reply with an error message.</t>
</section>
<section title="OAM Configuration TLV">
<t>This TLV is specified in [OAM-CONF-FWK] and is used to select which
OAM technology/method should be used for the LSP. In this document a
new OAM Type: BFD OAM is defined.</t>
<texttable align="center" anchor="table_example" suppress-title="true"
title="">
<ttcol align="left">OAM Type</ttcol>
<ttcol align="left">Description</ttcol>
<c>0</c>
<c>Reserved</c>
<c>1</c>
<c>Ethernet OAM</c>
<c>2 </c>
<c>BFD</c>
<c>2-256</c>
<c>Reserved</c>
<postamble>The receiving node when the BFD OAM Type is requested
should look for the corresponding technology specific BFD OAM
configuration TLV.</postamble>
</texttable>
</section>
<section title="BFD OAM Configuration TLV">
<t>The BFD OAM Configuration TLV (depicted below) is defined for BFD
OAM specific configuration parameters. The BFD OAM Configuration TLV
is carried in the LSP_ATTRIBUTES object both in Path and Resv messages.
This new TLV accommodates generic BFD OAM information and carries sub-TLVs.</t>
<t>
<figure>
<artwork><![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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (4) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Vers.|R| Reserved (set to all 0s) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ sub TLVs ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
</t>
<t>Type: indicates a new type, the BFD OAM
Configuration TLV (4) (IANA to define).</t>
<t>Length: indicates the total length including sub-TLVs.</t>
<t>Version: identifies the BFD protocol version. If a node does not
support a specific BFD version an error must be generated:
“OAM Problem/Unsupported OAM Version ”</t>
<t>R Flag: Role Flag. If set, the receiving node is required to
act with an Active Role as described in [BFD], section 6.1.
When the BFD OAM Configuration TLV is carried in the Resv message,
the flag it not taken into consideration by the receiving node.</t>
</section>
<section title="Local Discriminator Sub-TLV">
<t>The Local Discriminator sub-TLV is depicted below.</t>
<t>
<figure>
<artwork><![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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (1) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Discriminator |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
</t>
<t>Type: indicates a new type, the Local Discriminator sub TLV (1)
(IANA to define).</t>
<t>Length: indicates the total length of the TLV including padding.</t>
<t>Local Discriminator: A unique, nonzero discriminator value
generated by the transmitting system and referring to itself,
used to demultiplex multiple BFD sessions between the same pair of systems.
This Discriminator will be signaled both by the ingress LSR and the egress
LSR in the Path and Resv message respectively.</t>
</section>
<section title="Required TX interval">
<t>The Required TX interval sub-TLV is depicted below.</t>
<t>
<figure>
<artwork><![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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type (3) (IANA) | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Asynchronous TX interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Required Echo TX Interval |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Detect. Mult | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
</figure>
</t>
<t>Type: indicates a new type, the Required TX interval sub TLV (3)
(IANA to define).</t>
<t>Length: indicates the total length of the TLV including padding.</t>
<t>Required Asynchronous TX interval: the interval, in microseconds,
that the local system would like to have when both transmitting and receiving
BFD Control packets, less any jitter applied. The value zero is reserved.
If the receiving system can not support this value it will return an error.</t>
<t>Required Echo TX Interval: the minimum interval, in microseconds,
between received BFD Echo packets that this system is capable of supporting,
less any jitter applied by the sender as described in [BFD], section 6.8.9.
This value is also an indication for the receiving system of the minimum
interval between transmitted BFD Echo packets. If this value is zero, the
transmitting system does not support the receipt of BFD Echo packets.
If the receiving system can not support this value it will return an error.</t>
<t>Detect Mult: detection time multiplier. The transmit interval,
multiplied by this value, provides the Detection Time for the transmitting
and receiving system in Asynchronous mode.</t>
</section>
</section>
<!-- Possibly a 'Contributors' section ... -->
<section anchor="IANA" title="IANA Considerations">
<t>This document specifies a new BFD OAM Configuration TLV to be
carried in the OAM Configuration TLV in LSP_ATTRIBUTES and
LSP_REQUIRED_ATTRIBUTES objects in Path messages.</t>
</section>
<section anchor="Security" title="Security Considerations">
<t>
This document does not introduce any new security considerations.
</t>
</section>
</middle>
<!-- *****BACK MATTER ***** -->
<back>
<!-- References split into informative and normative -->
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<references title="Normative References">
<!--?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.2119.xml"?-->
<?rfc include="reference.RFC.3471"?>
<?rfc include="reference.RFC.2119"?>
<reference anchor="MPLS-TP-OAM-REQ"
target="http://www.example.com/dominator.html">
<!-- the following is the minimum to make xml2rfc happy -->
<front>
<title>Requirements for OAM in MPLS Transport Networks</title>
<author initials="M" surname="Vigoureux">
<organization></organization>
</author>
<author initials="D" surname="Ward">
<organization></organization>
</author>
<author initials="M" surname="Betts">
<organization></organization>
</author>
<date year="2009" />
</front>
</reference>
<reference anchor="BFD"
target="draft-ietf-bfd-base-09.txt">
<!-- the following is the minimum to make xml2rfc happy -->
<front>
<title>Bidirectional Forwarding Detection</title>
<author initials="D" surname="Katz">
<organization></organization>
</author>
<author initials="D" surname="Ward">
<organization></organization>
</author>
<date year="2009" />
</front>
</reference>
<reference anchor="OAM-CONF-FWK"
target="draft-ietf-ccamp-oam-configuration-fwk-01">
<!-- the following is the minimum to make xml2rfc happy -->
<front>
<title>OAM Configuration Framework for GMPLS RSVP-TE</title>
<author initials="A" surname="Takacs">
<organization></organization>
</author>
<author initials="D" surname="Fedyk">
<organization></organization>
</author>
<author initials="J" surname="van He">
<organization></organization>
</author>
<date year="2009" />
</front>
</reference>
</references>
<references title="Informative References">
<reference anchor="MPLS-TP OAM Analysis"
target="draft-sprecher-mpls-tp-oam-analysis-04.txt">
<!-- the following is the minimum to make xml2rfc happy -->
<front>
<title>MPLS-TP OAM Analysis</title>
<author initials="N" surname="Sprecher">
<organization></organization>
</author>
<author initials="T" surname="Nadeau">
<organization></organization>
</author>
<author initials="H" surname="van Helvoort">
<organization></organization>
</author>
<author initials="" surname="Weingarten">
<organization></organization>
</author>
<date year="2006" />
</front>
</reference>
<reference anchor="LSP Ping"
target="RFC 3479">
<!-- the following is the minimum to make xml2rfc happy -->
<front>
<title>Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures</title>
<author initials="K" surname="Kompella">
<organization></organization>
</author>
<author initials="G" surname="Swallow">
<organization></organization>
</author>
<date year="2006" />
</front>
</reference>
</references>
<section anchor="app-additional" title="Additional Stuff">
<t>This becomes an Appendix.</t>
</section>
</back>
</rfc>
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