Network Working Group Thomas D. Nadeau
Internet Draft Cisco Systems, Inc.
Expires: August 2004
Rahul Aggarwal
Juniper Networks
Editors
February 2004
Pseudo Wire (PW) Virtual Circuit Connection Verification
(VCCV)
draft-ietf-pwe3-vccv-02.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
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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
(VCCV) procedures for use with pseudowire connections. VCCV
supports connection verification applications for pseudowire
VCs regardless of the underlying MPLS or IP tunnel technology.
VCCV makes use of IP based protocols such as Ping and MPLS
LSP Ping to perform operations and maintenance functions. This
is accomplished by providing an IP control channel associated
with each pseudowire. A network operator may use the VCCV
procedures to test the network's forwarding plane liveliness.
Contents
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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
12. Full Copyright Statement.............................................13
1. Contributors
Thomas D. Nadeau Rahul Aggarwal
Cisco Systems, Inc. Juniper Networks
300 Beaver Brook Road 1194 North Mathilda Ave.
Boxborough, MA 01719 Sunnyvale, CA 94089
Email: tnadeau@cisco.com Email: rahul@juniper.net
George Swallow Monique Morrow
Cisco Systems, Inc. Cisco Systems, Inc.
300 Beaver Brook Road Glatt-com
Boxborough, MA 01719 CH-8301 Glattzentrum
Email: swallow@cisco.com Switzerland
Email: mmorrow@cisco.com
Yuichi Ikejiri Kenji Kumaki
NTT Communication Corporation KDDI Corporation
1-1-6, Uchisaiwai-cho, Chiyoda-ku KDDI Bldg. 2-3-2,
Tokyo 100-8019 Nishishinjuku,
Shinjuku-ku, JAPAN Tokyo 163-8003,
Email: y.ikejiri@ntt.com JAPAN
E-mail: ke-kumaki@kddi.com
Peter B. Busschbach Vasile Radoaca
Lucent Technologies Nortel Networks
67 Whippany Road Billerica, MA, 01803
Whippany, NJ, 07981 Email: vasile@nortelnetworks.com
E-mail: busschbach@lucent.com Voice: 978-288-6097
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).
|<----- Pseudo Wire ---->|
| |
Emulated | |<-- PSN Tunnel -->| | Emulated
Service V V V V Service
| +----+ +----+ |
+----+ | | PE1|==================| PE2| | +----+
| |----------|............PW1.............|----------| |
| CE1| | | | | | | |CE2 |
| |----------|............PW2.............|----------| |
+----+ | | |==================| | | +----+
^ +----+ +----+ | ^
| Provider Edge 1 Provider Edge 2 |
| |
|<-------------- Emulated Service ---------------->|
|<---------- VCCV ------>|
Customer Customer
Edge 1 Edge 2
Figure 1: PWE3 VCCV Operation Reference Model
Figure 1 depicts the basic functionality of VCCV. VCCV provides
several means of creating a control channel between PEs that
attaches the VC under test.
+-------------+ +-------------+
| Layer2 | | Layer2 |
| Emulated | | Emulated |
| Services | Emulated Service | Services |
| | | |
+-------------+ VCCV/pseudowire +-------------+
|Demultiplexer| |Demultiplexor|
+-------------+ +-------------+
| PSN | PSN Tunnel | PSN |
| MPLS | | MPLS |
+-------------+ +-------------+
| Physical | | Physical |
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+-----+-------+ +-----+-------+
| |
| ____ ___ ____ |
| _/ \___/ \ _/ \__ |
| / \__/ \_ |
| / \ |
---------| MPLS or IP Network |-----
\ /
\ ___ ___ __ _/
\_/ \____/ \___/ \____/
Figure 2: PWE3 Protocol Stack Reference Model
including the VCCV control channel.
Figure 2 depicts how the VCCV IP control channel is associated
with the pseudowire. Ping and other IP messages are encapsulated
using the PWE3 encapsulation as described below in sections 5 and
6. These messages, referred to as VCCV messages, are exchanged
only after the desire to exchange such traffic has been
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
verify connectivity of the pseudowire. To make sure that pseudowire
packets follow the same path as the data flow, they are encapsulated
with the same labels. VCCV can operate in two modes:
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
pseudowire is bi-directional, it makes sense to require that the
reply is send over the PSN tunnel that makes up the other half
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
determine what is wrong. The specific type of reply mode is
indicated during PW circuit set-up (see section 6).
The fault detection mode provides a way to emulate fault
detection mechanisms in other technologies, such as ATM for
example. In the fault detection mode, the upstream PE sends
BFD control messages periodically. [BFD-MPLS] describes
procedures for using BFD to detect liveliness of MPLS LSPs.
When the downstream PE doesn't receive these message for
a defined period of time, it declares that direction of the
PW down and it notifies the upstream PE. Based on the emulated
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service, the PEs may send FDI and RDI indications over the related
attachment circuits to notify the end points of the fault condition.
This is described in more detail in [OAMMsgMap].
3.1 LSP Ping
When the PSN is MPLS, the LSP Ping header is used as described
in [LSP-PING] for verifying the connectivity status of pseudo
wires.
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 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
VCCV mechanism is needed in particular for verifying the session
forwarding state at the egress router.
3.3 ICMP Ping
When IP is used as the PSN, ICMP ECHO packets can be used
as the means by which connectivity verification is achieved
using VCCV.
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
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.
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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
the IP control channel is also proposed. This is described in
section 7.2.
The actual channel type is agreed through signaling as
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 1| Flags |FRG| Length | Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
for the purpose of indicating VCCV control channel messages.
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.
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
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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
packets used is indicated during signaling as described in
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.
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
BFD session to a particular pseudowire (FEC). Thus normal BFD
initialization procedures are followed. BFD MUST be run in
asynchronous mode.
It may be desirable to use LSP-Ping additionally for periodic
diagnostics in addition to BFD for fault detection on the same PW.
[BFD-MPLS] provides further details on how BFD can be used in
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conjunction with LSP-Ping for detecting the liveliness
of MPLS LSPs.
When one of the PEs (PE2) doesn't receive control messages
from PE1 during the specified amount of time, or if it
determines in another way that communication is lost,it
declares that the PW in the direction from PE1 to PE2 is down.
It stores the cause (e.g. control detection time expired) and
sends a message to PE1 with H=3D0 (i.e. "I don't hear you"). In
turn, PE1 declares the PW in the direction from PE1 to PE2
down and stores as cause: neighbor signaled session down.
Depending on the emulated services, PE2 may send a FDI
indication on its attachment circuits and PE1 may send an RDI
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
to asynchronous mode.
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
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. When a PE sends a label for a PW, it uses the VCCV parameter
to indicate the type of OAM channels it is willing to receive on that
PW. The capablity of supporting a control channel MUST be signaled
BEFORE the remote PE may send OAM messages, and then only on the type
of control channel indicated.
If a PE receives OAM messages prior to sending
a VCCV parameter, it MUST discard these messages and not reply
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to them. In this case, the LSR SHOULD increment an error counter
and optionally issues a system and/or SNMP notification to indicate
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 channel options. The absence of the VCCV FEC TLV
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
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 PW again.
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 0
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| 0x0a | 0x04 |CC Type| CV Type Indicators |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The CC type field defines the type of IP control channel
that will be used to receive. The defined values are:
0x01 PWE3 control word (0x0001 as first nibble of CW)
0x02 MPLS Router Alert Label
The CV Type Indicators field defines a bitmask used to indicate the
specific type or types (i.e.: one or more) of IP control packets
that may be sent on the control channel. The defined values
are:
0x01 ICMP Ping
0x02 LSP Ping
0x04 BFD
If none of the types above are supported, a CV Type Indicator
of 0x00 SHOULD be transmitted to indicate this to the peer. However,
if no capability is signaled, then the peer MUST assume that
the peer has no VCCV capability.
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
VCCV mechanism is needed in particular for verifying the session
forwarding state at the egress router.
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
format.
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
has not been signaled to include a L2-specific sublayer format, other
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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
messageheader. A new AVP, called the VCCV AVP is defined. The usage of
the L2TPv3 AVP format leaves room for adding further AVPs to this
message in the future as needed.
7.1.1. L2TPv3 VCCV AVP
This AVP encodes the LSP Ping header as defined in [LSP-PING]. M and H
bits must not be set. The attribute type is TBD. The LSP Ping header
is not encapsulated in UDP. The modifications to the semantics of the
fields of this header are specified here. Unless otherwise specified
the semantics of the fields as explained in [LSP-PING] are to be
followed. For reference the format of the LSP Ping header is shown
below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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
following:
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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 a reply mode of "reply using the L2TPv3 session".
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 pseudowire
4 - Replying router does not have a mapping for the verified pseudowire
The LSP Ping header must contain the L2 Circuit ID TLV as defined in
section 8.2. This TLV identifies the pseudo wire associated with the
session, that is being verified. For L2TPv3 the remote PE address is
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
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
7.3. L2TPv3 VCCV Operation
A PE sends VCCV echo requests on a L2TPv3 signaled pseudo wire for
fault detection and diagnostic of the L2TPv3 session. The destination
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IP address in the echo request is set to the remote PE's IP address,
while the source IP address is set to the local PE's IP address. The
egress of the L2TPv3 session verifies the signaling and forwarding
state of the pseudo wire, on reception of the VCCV message. Any faults
detected can be signaled in the VCCV echo response. Its to be noted
that the VCCV mechanism for L2TPv3 is primarily targeted at verifying
the pseudo wire forwarding and signaling state at the egress PE. It
also helps when L2TPv3 control and session paths are not identical.
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 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 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 increment an error counter. In this case the PE can
optionally issue a system and/or SNMP notification.
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-01.txt, August
2003, work in progress.
[PWREQ] Xiao, X., McPherson, D., Pate, P., "Requirements for
Pseudo Wire Emulation Edge to-Edge (PWE3)", <
draft-ietf-pwe3-requirements-08.txt>, December 2003
[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.
[PWEARCH] Bryant, S., Pate, P., "PWE3 Architecture", Internet
Draft, < draft-ietf-pwe3-arch-06.txt>, October 2003
[PWE3IANA] Martini, L., Townsley, M., "IANA Allocations fo
pseudo Wire Edge to Edge Emulation (PWE3)",
draft-ietf-pwe3-iana-allocation-01.txt, June
2003, work in progress.
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[L2SIG] Rosen, E., LDP-based Signaling for L2VPNs,
Internet Draft <draft-rosen-ppvpn-l2-signaling-02.txt>,
September 2002.
[LSPPING] Kompella, K., Pan, P., Sheth, N., Cooper, D., Swallow,
G., Wadhwa, S., Bonica, R., " Detecting MPLS Data Plane
Failures", Internet Draft < draft-ietf-mpls-lsp-ping-04.txt>,
October 2003
[MARTINISIG] "Transport of Layer 2 Frames Over MPLS", Martini et.
al., draft-martini-l2circuit-trans-mpls-10.txt,
August 2002
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-02.txt>, June 2003.
[OAMMsgMap] Nadeau, T., et al, " Pseudo Wire (PW) OAM Message
Mapping, Internet Draft < draft-nadeau-pwe3-oam-msg-map-04.txt>,
January, 2004.
[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 3031,
January 2001.
[BFD-MPLS] Aggarwal, R. Kompella, K. "BFD for MPLS LSPs", Internet
Draft <draft-raggarwa-mpls-bfd-00.txt>, October 2003.
10. Security Considerations
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TBD.
11. Intellectual Property Rights Notices
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NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
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