Network Working Group Thomas D. Nadeau
Internet Draft Cisco Systems, Inc.
Expires: April 2004 =20
Rahul Aggarwal
Juniper Networks
Editors
=20
October 2003
Pseudo Wire (PW) Virtual Circuit Connection Verification
(VCCV)
draft-ietf-pwe3-vccv-01.txt
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC 2026. Internet-Drafts are
working documents of the Internet Engineering Task Force (IETF), its
areas, and its working groups. Note that other groups may also
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
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http://www.ietf.org/shadow.html
Distribution of this document is unlimited. Please send comments to
the Multiprotocol Label Switching (mpls) Working Group, mpls@uu.net.
Abstract
This document describes Virtual Circuit Connection Verification=20
(VCCV) procedures for use with pseudowire connections. VCCV=20
supports connection verification applications for pseudowire=20
VCs regardless of the underlying MPLS or IP tunnel technology. =20
VCCV makes use of IP based protocols such as Ping and MPLS
LSP Ping to perform operations and maintenance functions. This=20
is accomplished by providing an IP control channel associated
with each pseudowire. A network operator may use the VCCV=20
procedures to test the network's forwarding plane liveliness.
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Contents
=20
Abstract...............................................................1
1.
Contributors...........................................................1
2.
Introduction...........................................................2
3. Overview of VCCV Modes of
Operation....................................3
4. MPLS as
PSN............................................................3
5. IP Probe
Traffic.......................................................5
6. OAM Capability
Indication..............................................6
7. L2TPv3/IP as
PSN.......................................................8
8.
Acknowledgments.......................................................11
9.
References............................................................11
9.2 Normative
References.................................................11
9.2 Informative
References...............................................11
10. Security
Considerations..............................................12
11. Intellectual Property Rights
Notices.................................12=20
12. Full Copyright
Statement.............................................13
1. Contributors
Thomas D. Nadeau Rahul Aggarwal
Cisco Systems, Inc. Juniper Networks
250 Apollo Drive 1194 North Mathilda Ave.
Chelmsford, MA 01824 Sunnyvale, CA 94089
Email: tnadeau@cisco.com Email: rahul@juniper.net
George Swallow Monique Morrow
Cisco Systems, Inc. Cisco Systems, Inc.
250 Apollo Drive Glatt-com
Chelmsford, MA 01824 CH-8301 Glattzentrum
Email: swallow@cisco.com Switzerland
Email: mmorrow@cisco.com
=20
Yuichi Ikejiri Kenji Kumaki
NTT Communications Corporation KDDI Corporation
1-1-6, Uchisaiwai-cho, Chiyoda-ku KDDI Bldg. 2-3-2,
Tokyo 100-8019 Nishishinjuku,
Shinjuku-ku,=20
JAPAN Tokyo 163-8003,
Email: y.ikejiri@ntt.com JAPAN
E-mail :
ke-kumaki@kddi.com=20
Peter B. Busschbach
Lucent Technologies
67 Whippany Road
Whippany, NJ, 07981
E-mail: busschbach@lucent.com
2. Introduction
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As network operators deploy pseudowire services, fault
detection and diagnostic mechanisms particularly for the PSN
portion of the network are pivotal. Specifically, the ability
to provide end-to-end fault detection and diagnostics for an
emulated pseudowire service is critical for the network
operator. Operators have indicated in [MPLSOAMREQS] that such
a tool is required for pseudowire deployments. This document
describes procedures for PSN-agnostic fault detection and
diagnostics called virtual circuit connection verification
(VCCV).
|<------- pseudowire ------>|
| |<-- PSN Tunnel -->| |
PW V V V V PW
End Service +----+ +----+ End Service
+-----+ | | =
PE1|=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D| PE2| | =
+-----+
| |----------|............PW1.............|------------| |
| CE1 | | | | | | | | CE2 |
| |----------|............PW2.............|------------| |
+-----+ | | =
|=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D| | | =
+-----+
Customer | +----+ +----+ | Customer
Edge 1 | Provider Edge 1 Provider Edge 2 | Edge 2
|<----------- Emulated Service ---------->|
|<---------- VCCV ---------->|
Figure 1: PWE3 VCCV Operation Reference Model
Figure 1 depicts the basic functionality of VCCV. VCCV provides=20
several means of creating a control channel between PEs that=20
attaches the VC under test.=20
=20
+-------------+ +-------------+
| Layer2 | | Layer2 |
| Emulated | | Emulated |
| Services | Emulated Service | Services |
| =
|<=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D>| |
+-------------+ VCCV/pseudowire +-------------+
=
|Demultiplexer|<=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D>|Demultiplexor|
+-------------+ +-------------+
| PSN | PSN Tunnel | PSN |
| MPLS =
|<=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D>| MPLS |
+-------------+ +-------------+
| Physical | | Physical |
+-----+-------+ +-----+-------+
| |
| ____ ___ ____ |
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| _/ \___/ \ _/ \__ |
| / \__/ \_ |
| / \ |
+=3D=3D=3D=3D=3D=3D=3D=3D/ MPLS or IP Network =
|=3D=3D=3D+
\ /
\ ___ ___ __ _/
\_/ \____/ \___/ \____/
Figure 2: PWE3 Protocol Stack Reference Model=20
including the VCCV control channel.
Figure 2 depicts how the VCCV IP control channel is associated=20
with the pseudowire. Ping and other IP messages are encapsulated=20
using the PWE3 encapsulation as described below in sections 5 and=20
6. These messages, referred to as VCCV messages, are exchanged=20
only after the desire to exchange such traffic has been=20
negotiated between the PEs (see section 8).
3. Overview of VCCV Modes of Operation
VCCV defines a set of messages that are exchanged between PEs to=20
verify connectivity of the pseudowire. To make sure that pseudowire
packets follow the same path as the data flow, they are encapsulated=20
with the same labels. Operators can use VCCV in two ways:
1) as a diagnostic tool
2) as a fault detection tool
In the diagnostic mode, the operator triggers LSP-Ping, L2TPV3,
or ICMP Ping modes depending on the underlying PSN. Since a=20
pseudowire is bi-directional, it makes sense to require that the=20
reply is send over the PSN tunnel that makes up the other half=20
of the PW under test. For example, if the PSN is an MPLS LSP,
the reply should be sent on the LSP representing the reverse
path. If this fails, the operator can use other reply modes to=20
determine what is wrong.
The fault detection mode is provides a way to emulate fault=20
detection mechanisms in other technologies, such as ATM for=20
example. In the fault detection mode, the upstream PE sends=20
BFD control messages periodically. When the downstream PE=20
doesn't receive these message for a defined period of time, it=20
declares that direction of the PW down and it notifies the=20
upstream PE. Based on the emulated service, the PEs may send=20
FDI and RDI indications over the related attachment circuits
to notify the end points of the fault condition.
3.1 LSP Ping
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When the PSN is MPLS, the LSP Ping header is used as described=20
in [LSP-PING] for verifying the connectivity status of pseudo
wires.=20
3.2 L2TPV3
When L2TPv3 is used as the underlying PSN, a VCCV mechanism is
needed for the L2TPv3 session. The L2TPv3 control connection does
employ a keepalive mechanism; however, this mechanism isn't=20
sufficent for fault detection and diagnostic of the L2TPv3 session
i.e. data plane. In L2TPv3, a session is analogous to a PW. A L2TPv3=20
VCCV mechanism is needed in particular for verifying the session=20
forwarding state at the egress router.=20
3.3 ICMP Ping
When IP is used as the PSN, ICMP ECHO packets can be used=20
as the means by which connectivity verificaiton is achived
using VCCV.=20
3.4 Bidirectional Forwarding Detection
When heart-beat indication is necessary for one or more
pseudowires, the Bidirectional Forwarding Detection (BFD)
[BFD] provides a light-weight means of continuous
monitoring and propagation of forward and reverse defect
indications. BFD can be used regardless of the underlying
PSN technology.
4. MPLS as PSN
In order to apply IP monitoring tools to PWE3 circuits, VCCV
creates a control channel between PWE3 PEs[PWEARCH]. Packets=20
sent across this channel are IP packets, allowing maximum
flexibility.
Ideally such a control channel would be completely in band.
When a control word is present on virtual circuit, it is
possible to indicate the control channel by setting a bit in
the control header. This method is described in section 7.1
and is referred to as PWE3 inband VCCV.
However in order to address the case when the control header
is not in use as well as to deal with a number of existent
hardware devices, use of the MPLS Router Alert Label to indicate=20
the IP control channel is also proposed. This is described in
section 7.2.
The actual channel type is agreed through signaling as
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described in section 8.
4.1. PWE3 Inband VCCV
The PW set-up protocol determines whether a PW uses a control word.
When a control word is used, it SHOULD have the following preferred
form:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0| Flags |FRG| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
for the purpose of indicating VCCV control channel messages.=20
Note that for data, one uses the control word defined just
above the MPLS payload [PWEARCH].
The PWE3 payload type identifier is defined as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1| reserved | PPP DLL Protocol Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| As defined by PPP DLL protocol definition |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The first nibble 0000 indicates data. When the first nibble is=20
0001, the protocol of the frame is indicated by the Protocol
Number. IP OAM flows are identified by either an IPv4 or IPv6
codepoint.=20
4.2. Router Alert Label Approach
When the control word is not used, or the receiving hardware
cannot divert control traffic based on information in the control
word (i.e.: older hardware), an IP control channel can be
created by including the MPLS router alert label immediately
above the VC label. If the control word is in use on this VC
it is also included in the IP control flow.
5. IP Probe Traffic
For connectivity verification, both ICMP Ping and LSP-Ping
packets may be used on the control channel. The type of
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packets used is indicated during signaling as described in=20
section 6.
5.1. ICMP Ping
When ICMP packets are used, the source address should be set
to the source address of the LDP session and the destination
address to the destination of the LDP session. The Identifier
and Sequence Number fields of the ICMP Echo Request/Echo
Reply messages are used to track what VCs are being tested.
These fields are only interpreted by the sending PE. Specific
use of these fields is an implementation matter.
5.2. MPLS Ping Packet
The LSP Ping header must be used as described [LSP-PING] and
must also contain the sub-TLV of 8 for PW circuits. This
sub-TLV must be sent containing the circuit to be verified as
the "VC ID" field:
5.3 Bidirectional Forwarding Detection
When heart-beat indication is necessary for one or more
pseudowires, the Bidirectional Forwarding Detection (BFD)
[BFD] provides a light-weight means of continuous
monitoring and propagation of forward and reverse defect
indications. =20
In order to use BFD, both ends of the pseudowire connection must
have signaled the existence of a control channel and the ability to
run BFD. Once a node has both signaled and received signaling from
its peer of these capabilities, it MUST begin sending BFD control
packets. The packets MUST be sent on the control channel. The use
of the control channel provides the context required to bind the=20
BFD session to a particular pseudowire (FEC). Thus normal BFD=20
initialization procedures are followed. BFD MUST be run in=20
asynchronous mode.
When one of the PEs (PE2) doesn't receive control messages=20
from PE1 during the specified amount of time, or if it=20
determines in another way that communication is lost , it=20
declares that the PW in the direction from PE1 to PE2 is down.=20
It stores the cause (e.g. control detection time expired) and=20
sends a message to PE1 with H=3D0 (i.e. "I don't hear you"). In=20
turn, PE1 declares the PW in the direction from PE1 to PE2=20
down and stores as cause: neighbor signaled session down.=20
Depending on the emulated services, PE2 may send a FDI=20
indication on its attachment circuits and PE1 may send an RDI=20
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indication on its attachment circuits.
BFD defines the following diagnostics:
0 -- No Diagnostic
1 -- Control Detection Time Expired
2 -- Echo Function Failed
3 -- Neighbor Signaled Session Down
4 -- Forwarding Plane Reset (Local equipment failure)
5 -- Path Down (Alarm Suppression)
6 -- Concatenated Path Down (Propagating access link alarm)
7 -- Administratively Down
Of these, 0 is used when the PW is up and 2 is not applicable=20
to asynchronous mode.
=20
6. OAM Capability Indication
To permit negotiation of the use and type of OAM for
Connectivity Verification, a VCCV parameter is defined below.
When a PE signals a PWE3 VC and desires OAM for that VC, it
MUST indicate this during VC establishment using the messages
defined below. Specifically for LDP it MUST include the VCCV=20
parameter in the VC setup message.
As the overall method of PWE3 signaling is
downstream, unsolicited, the decision of the type
of IP control channel is left completely to the receiving control
entity. OAM capability MUST be signaled BEFORE a PE may send
OAM messages. If a PE receives OAM messages prior to sending
a VCCV parameter, it MUST discard these messages and not reply
to them. In this case, the LSR SHOULD increment an error counter=20
and optionally issues a system and/or SNMP notification to indicate=20
to the system administrator that a mis-configuration exists.
The requesting PE indicates its desire for the remote PE to
support OAM capability by including the VCCV parameter with
appropriate options set to indicate which methods of OAM are
acceptable. The requesting PE MAY indicate multiple IP control
IP control channel options. The absence of the VCCV FEC TLV=20
indicates that no OAM functions are supported or desired by
the requesting PE. This last method MUST be supported by all
PEs in order to handle backward-compatibility with older PEs.
The receiving PE agrees to accept any of the indicated=20
OAM types and options by virtue of establishing the VC. If
it does not or cannot support at least one of the options
specified, it MUST not establish the VC. If the requesting
PE wishes to continue, it may choose different options and
try to signal the PE again.
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6.1. Optional VCCV Parameter
[PWE3CONTROL] defines a VC FEC TLV for LDP. Parameters can be
carried within that TLV to signal different capabilities for
specific PWs. We propose an optional parameter to be used to
indicate the desire to use a control channel for VCCV as
follows.
The TLV field structure is defined in [PWE3CONTROL] as
follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter ID | Length | Variable Length Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Length Value |
| " |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The VCCV parameter ID is defined as follows in [PWE3IANA]:
Parameter ID Length Description
0x0a 4 VCCV
The format of the VCCV parameter TLV is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0a | 0x04 | CC Type | CV Types |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The CC type field defines the type of IP control channel.
The defined values are:
0x1 OAM Flag set in PWE header
0x2 MPLS Router Alert Label
The CV Types field defines the types of IP control packets
that may be sent on the control channel. The defined values=20
are:
0x01 ICMP Ping
0x02 LSP Ping=20
0x03 BFD
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7. L2TPV3 as PSN
When L2TPv3 is used as the underlying PSN, a VCCV mechanism is
needed for the L2TPv3 session. The L2TPv3 control connection does
employ a keepalive mechanism. However this mechanism is not
sufficent for fault detection and diagnostic of the L2TPv3 session
i.e. data plane. In L2TPv3 a session is analogous to a PW. A L2TPv3=20
VCCV mechanism is needed in particular for verifying the session=20
forwarding state at the egress router.=20
When a PE verifies the connection status of a L2TPv3 session it must
transmit a L2TPv3 VCCV message encoded in the L2TPv3 session packet.
The presence of a VCCV message in a L2TPv3 session packet can be
indicated by reserving a bit in the default L2-specific sublayer=20
format.=20
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|P|S|V|x|x|x|x|x| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Default L2-Specific Sublayer Format with V bit.
The 'V' bit indicates that this is a VCCV session packet. If the PW=20
has not been signaled to include a L2-specific sublayer format, other
mechanisms are needed to indicate the VCCV message. Such mechanisms
are
for further study.
7.1. L2TPv3 VCCV Message
The VCCV message MUST contain a VCCV AVP. It does not contain a
message
header. A new AVP, called the VCCV AVP is defined. The usage of the=20
L2TPv3 AVP format leaves room for adding further AVPs to this message
in the future as needed.=20
7.1.1. L2TPv3 VCCV AVP
This AVP encodes the LSP Ping header as defined in [LSP-PING]. M and
H=20
bits must not be set. The attribute type is TBD. The LSP Ping header
is=20
not encapsulated in UDP. The modifications to the semantics of the=20
fields of this header are specified here. Unless otherwise specified=20
the semantics of the fields as explained in [LSP-PING] are to be=20
followed. For reference the format of the LSP Ping header is shown=20
below.
0 1 2 3
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version Number | Must Be Zero |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Type | Reply mode | Return Code | Return Subcode|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender's Handle |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TimeStamp Sent (seconds) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TimeStamp Sent (microseconds) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TimeStamp Received (seconds) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TimeStamp Received (microseconds) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLVs ... |
. .
. .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The version number is currently 1. The message type is one of the=20
following:
1 - L2TPv3 VCCV Echo Request
2 - L2TPv3 VCCV Echo Reply
The Reply Mode is:
1 - Do not reply
2 - Reply using the L2TPv3 session
As explained in [LSP-PING] a reply mode of "do not reply" can be used
for one way connectivity tests. The VCCV message will normally
contain=20
a reply mode of "reply using the L2TPv3 session".=20
The return code can be set to the following by the receiver:
1 - Malformed echo request received
2 - One or more of the TLVs was not understood
3 - Replying router has a session mapping for the verified pseudo
wire
4 - Replying router does not have a mapping for the verified pseudo=20
wire
The LSP Ping header must contain the L2 Circuit ID TLV as defined in=20
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section 8.2. This TLV identifies the pseudo wire associated with the
session, that is being verified. For L2TPv3 the remote PE address is=20
the address of the session's remote end. A new PWID type is defined
for L2TPv3, in addition to the ones defined in section 8.2:
3. L2TPv3 Remote End Identifier AVP
7.2. L2TPv3 VCCV Capability Negotiation
A LCCE or a LAC should be able to indicate whether the session is
capable of processing VCCV packets. This is done by including the
optional VCCV capability AVP in an ICRQ, ICRP, OCRQ or OCRP.
7.2.1. L2TPv3 VCCV Capability AVP
This AVP specifies the VCCV capability. Its attribute type
is TBD. The value field has the following format:
0 1 =20
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-=20
7.3. L2TPv3 VCCV Operation
A PE sends VCCV echo requests on a L2TPv3 signaled pseudo wire for=20
fault detection and diagnostic of the L2TPv3 session. The destination
IP address in the echo request is set to the remote PE's IP address,=20
while the source IP address is set to the local PE's IP address. The=20
egress of the L2TPv3 session verifies the signaling and forwarding
state
of the pseudo wire, on reception of the VCCV message. Any faults=20
detected can be signaled in the VCCV echo response. Its to be noted=20
that the VCCV mechanism for L2TPv3 is primarily targeted at verifying
the pseudo wire forwarding and signaling state at the egress PE. It=20
also helps when L2TPv3 control and session paths are not identical.=20
A PE must send VCCV packets on a L2TPv3 session only if it has
signaled
VCCV capability to the remote end and received VCCV capability from
the=20
remote end. If a PE receives VCCV packets and its not VCCV capable or
it has not received VCCV capability indication from the remote end,
it=20
must discard these messages. In addition if a PE receives VCCV
messages
and it has not received VCCV capability from the remote end, it
should=20
increment an error counter. In this case the PE can optionally issue
a
system and/or SNMP notification.
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8. Acknowledgments
The authors would like to thank Hari Rakotoranto, Michel
Khouderchah, Bertrand Duvivier, Vanson Lim, Chris Metz, W.
Mark Townsley, Eric Rosen, Dan Tappan, and
Danny McPherson for their valuable comments and suggestions.
9. References
9.1 Normative References
[BFD] Katz, D., Ward, D., Bidirectional Forwarding
Indication, draft-katz-ward-bfd-00.txt, December
2003, work in progress.
[PWREQ] Xiao, X., McPherson, D., Pate, P., Gill, V.,
Kompella, K., Nadeau, T., White, C., "Requirements=20
for Pseudo Wire Emulation Edge-to-Edge (PWE3)",=20
<draft-ietf-pwe3-requirements-02.txt>, November 2001.
[PWE3FW] Prayson Pate, et al., Internet draft, Framework for
Pseudo Wire Emulation Edge-to-Edge (PWE3), draft-
ietf-pwe3-framework-01.txt, work in progress.=20
[PWEARCH] Bryant, S., Pate, P., Johnson, T., Kompella, K.,
Malis, A., McPherson, D., Nadeau, T., So, T., Townsley,=20
W., Systems, White., C., Wood, L., Xiao, X., Internet=20
draft, Framework for Pseudo Wire Emulation Edge-to-Edge=20
(PWE3), draft-ietf-pwe3-framework-01.txt, work in=20
progress.
[PWE3IANA] Martini, L., Townsley, M., "IANA Allocations for=20
pseudo Wire Edge to Edge Emulation (PWE3)",
draft-ietf-pwe3-iana-allocation-01.txt, June
2003, work in progress.
[L2SIG] Rosen, E., LDP-based Signaling for L2VPNs,
Internet Draft <draft-rosen-ppvpn-l2-signaling-02.txt>,=20
September 2002.
[LSPPING] Kompella, K., Pan, P., Sheth, N., Cooper, D.,
Swallow, G., Wadhwa, S., Bonica, R., " Detecting=20
Data Plane Liveliness in MPLS", Internet Draft=20
<draft-ietf-mpls-lsp-ping-01.txt>, April 2003.=20
[MARTINISIG] "Transport of Layer 2 Frames Over MPLS", Martini et.
al., draft-martini-l2circuit-trans-mpls-10.txt,=20
August 2002
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[GTTP] Bonica, R., Kompella, K., Meyer, D., "Generic
Tunnel Tracing Protocol (GTTP) Specification", Internet=20
Draft <draft-bonica-tunproto-01.txt>, April, 2003=20
[FRF 8.1] Frame Relay Forum, Frame Relay / ATM PVC Service
Interworking Implementation Agreement, February 2000
[ITU-T] "Draft Recommendation Y.17fw" (MPLS Management
Framework), July 2002.
[ITU-T] "Frame Relay Bearer Service Interworking," I.555,
September 2997.
[ITU-T], "Frame Relay Operations Principles and Functions",=20
I.620, October, 1996.
[ITU-T] Q.933, ISDN Digital Subscriber Signalling System
No. 1 (DSS 1) - Signalling specification for frame=20
mode basic call control, November 1995.
9.2 Informative References
[ICMP] Postel, J. "Internet Control Message Protocol, "
RFC 792
[PWEATM] Martini, L., et al., "Encapsulation Methods for
Transport of ATM Cells/Frame Over IP and MPLS=20
Networks", Internet Draft <draft-ietf-pwe3-atm-
encap-00.txt>, October 2002
[MPLSOAMREQS] Nadeau, T., et al,"OAM Requirements for MPLS
Networks, Internet Draft <draft-ietf-oam-
requirements-01.txt>, June 2003.
[OAMMsgMap] Nadeau, T., et al, " Pseudo Wire (PW) OAM Message
Mapping, Internet Draft < draft-nadeau-pwe3-OAMMap.txt>,
December, 2002.
[PWE3CONTROL] L.Martini et al., "Transport of Layer 2 Frames
over MPLS, Internet Draft, <draft-ietf-pwe3-control-
protocol-01.txt>, May 2003
[PPVPNFW] Callon, R., Suzuki, M., Gleeson, B., Malis, A.,
Muthukrishnan, K., Rosen, E., Sargor, C., and J. Yu,=20
"A Framework for Provider Provisioned Virtual=20
Private Networks", Internet Draft <draft-ietf-
ppvpn-framework-01.txt>, July 2001.
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon,
"Multiprotocol Label Switching Architecture", RFC=20
3031, January 2001.
10. Security Considerations
TBD.
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11. Intellectual Property Rights Notices
The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on=20
the IETF's procedures with respect to rights in standards-track and
standards-related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances
of licenses to be made available, or the result of an attempt made
to obtain a general license or permission for the use of such
proprietary rights by implementers or users of this specification=20
can be obtained from the IETF Secretariat.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF=20
Executive Director.
11. Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights
Reserved.
This document and translations of it may be copied and
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The limited permissions granted above are perpetual and
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DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
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HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR
PURPOSE.
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