One document matched: draft-ietf-mpls-tp-li-lb-02.txt
Differences from draft-ietf-mpls-tp-li-lb-01.txt
Network Working Group Sami Boutros (Ed.)
Internet Draft Siva Sivabalan (Ed.)
Intended status: Standards Track Cisco Systems, Inc.
Expires: December 5, 2011
Rahul Aggarwal (Ed.)
Juniper Networks, Inc.
Martin Vigoureux (Ed.)
Alcatel-Lucent
Xuehui Dai (Ed.)
ZTE Corporation
June 5, 2011
MPLS Transport Profile Lock Instruct and Loopback Functions
draft-ietf-mpls-tp-li-lb-02.txt
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on December 5, 2011.
Abstract
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This document specifies an extension to MPLS Operation,
administration, and Maintenance (OAM) to operate an Label Switched
Path (LSP), bi-directional RSVP-TE tunnels, Pseudowires (PW), or
Multi-segment PWs in loopback mode for management purpose in an MPLS
based Transport. This extension includes mechanism to lock and
unlock MPLS-TP Tunnels (i.e. data and control traffic) and can be
used to loop all traffic (i.e, data and control traffic) at a
specified LSR on the path of the LSP in an MPLS based Transport
Network back to the source. However, the mechanisms are intended to
be applicable to other aspects of MPLS as well.
Table of Contents
1. Introduction...................................................3
2. Terminology....................................................5
3. Loopback/Lock Mechanism........................................5
3.1. In-band Message Identification............................5
3.2. LI-LB Message Format......................................6
3.3. Return codes..............................................7
3.4. Cause codes...............................................7
3.5. Authentication TLV........................................8
3.6. LSP Ping Extensions.......................................9
3.6.1. LI-LB Request TLV....................................9
3.6.2. LI-LB Response TLV...................................9
4. Loopback/Lock Operations.......................................9
4.1. Lock Request.............................................10
4.2. Unlock Request...........................................10
4.3. Loopback Request.........................................10
4.4. Loopback Removal.........................................11
5. Data packets..................................................11
6. Operation.....................................................11
6.1. General Procedures.......................................11
6.2. Example Topology.........................................11
6.3. Locking an LSP...........................................12
6.4. Unlocking an LSP.........................................13
6.5. Setting an LSP into Loopback mode........................14
6.6. Removing an LSP from Loopback mode.......................15
7. Security Considerations.......................................16
8. IANA Considerations...........................................16
8.1. Pseudowire Associated Channel Type.......................16
8.2. New LSP Ping TLV types...................................16
9. Acknowledgements..............................................16
10. References...................................................16
10.1. Normative References....................................16
10.2. Informative References..................................17
Author's Addresses...............................................17
Full Copyright Statement.........................................19
Intellectual Property Statement..................................19
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1. Introduction
In traditional transport networks, circuits are provisioned across
multiple nodes and service providers have the ability to operate the
transport circuit such as T1 line in loopback mode for management
purposes, e.g., to test or verify connectivity of the circuit up to a
specific node on the path of the circuit, to test the circuit
performance with respect to delay/jitter, etc. This document provides
the same loopback capability for the bi-directional LSPs in MPLS
based Transport Networks emulating traditional transport circuits.
The mechanisms in this document apply to co-routed bidirectional
paths as defined in [7], which include LSPs, bi-directional RSVP-TE
tunnels, Pseudowires (PW), and Multi-segment PWs in MPLS based
Transport Networks. However, the mechanisms are intended to be
applicable to other aspects of MPLS as well.
This document specifies how to operate the Lock and Loopback
functions over both the Generic Associated Channel (GACh) and over
LSP-Ping. LSP-Ping itself can run either over the GACh or using
native IP addressing; the manner in which LSP-Ping is transported in
an MPLS-TP network is out of the scope of this document.
This document uses a sample topology to describe the lock instruct
and loopback functions. This sample topology comprises four MPLS-TP
nodes [A---B---C---D]. There is an LSP from A to D, and thus A and D
are MEPs and B and C are MIPs. Unless otherwise specified, the
operator desires to lock the LSP (this is done on A and D, by
definition) and loop the LSP at C.
That is, the desired behavior is that all packets transmitted by A on
this locked and looped LSP arrive at C from B and are encapsulated in
the D->A direction by C such that these packets reach A.
Locking and looping an LSP is a two-step process. The first step is
to lock the LSP so that it is not made available to carry user
traffic. The locking of an LSP is managed by the two MEPs of an LSP -
in this example, A and D. Locking is controlled by one of the MEPs;
this example uses A. A sends a Lock request message to D along the
LSP, either in the GACh or in LSP-Ping. This message will be
received by D as it is the far-end MEP for that LSP. D responds to
the lock request with an ACK or NACK; the ACK indicates that D has
taken the LSP out of service (i.e. Locked the LSP) and the NACK
indicates that D cannot comply with the Lock request. In general, if
a message (e.g. Lock request, Loopback request) cannot be complied
with, the node which received the request replies with a NACK and a
cause code; the details of error message processing are discussed
later in this document.
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Once A has received the ACK to its Lock request, A is then allowed to
put the LSP in Loopback mode. In order to set the LSP in Loopback
mode, A sends a Loopback request message to the MIP or MEP where A
desired the loopback to be enabled. In this example, A desires to
set the loopback at C, although note that it is possible to A to set
the loopback at any node downstream of A (e.g. B, C, D). The TTL on
the Loopback request message is set by A such that the TTL expires
when it reaches the node where A wants the loopback to be set (in
this case, C). C responds to the Loopback request with a reply
message (ACK/NACK) back to A to indicate whether it has successfully
set the LSP into the Loopback mode.
If A receives an ACK from its Loopback request, the LSP is now in
Loopback mode. A is free to send any test packets down this LSP as
it sees fit. These packets MUST NOT be forwared towards D. As the
LSP is locked, D MUST NOT transmit any traffic on the LSP in the
reverse direction (that is, D->A). Any traffic received by C from
the reverse direction MUST be dropped and MAY be logged, as the
receipt of traffic by C in the D->A direction indicates an error.
When A desires to remove the LSP from Loopback state, it begins to
reverse the Loopback and Lock. This is a two-step process; first A
removes the Loopback from C, then A removes the Lock from D. This
process is similar to the process of establishing Lock and Loopback
in the first place. A sends a Loopback Remove message to C using the
TTL method described above, and C ACKs or NACKs the Loopback Remove.
Once A receives the Loopback Remove ACK from C, A sends a Lock Remove
message to D. D must ACK or NACK this message. Once A receives the
Lock Remove ACK from D, the LSP is brought back into normal
operation.
The proposed mechanism is based on a new set of messages and TLVs
which can be transported using one of the following methods:
(1) An in-band MPLS message transported using a new ACH code point,
the message will have different types to perform the loopback
request/remove and Lock/unlock functions, and may carry new set of
TLVs.
(2) A new set of TLVs which can be transported using LSP-Ping
extensions defined in [4], and in compliance to specifications [5].
Method (1) and (2) are referred to as "in-band option" and "LSP-Ping
option" respectively in the rest of the document.
Conventions used in this document
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 RFC-2119 [3].
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2. Terminology
ACH: Associated Channel Header
LSR: Label Switching Router
MEP: Maintenance Entity Group End Point
MIP: Maintenance Entity Group Intermediate Point.
MPLS-TP: MPLS Transport Profile
MPLS-OAM: MPLS Operations, Administration and Maintenance
MPLS-TP LSP: Bidirectional Label Switch Path representing a circuit
NMS: Network Management System
TLV: Type Length Value
TTL: Time To Live
LI-LB: Lock instruct-Loopback
3. Loopback/Lock Mechanism
For the in-band option, the proposed mechanism uses a new code point
in the Associated Channel Header (ACH) described in [6].
3.1. In-band Message Identification
In the in-band option, the LI-LB channel is identified by the ACH as
defined in RFC 5586 [6] with the Channel Type set to the LI-LB code
point = 0xHH. [HH to be assigned by IANA from the PW Associated
Channel Type registry] The LI-LB Channel does not use ACH TLVs and
MUST not include the ACH TLV header. The LI-LB ACH
Channel 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|Version|Reserved | 0xHH ( LI-LB) | +-+-
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: ACH Indication of LI-LB
The LI-LB Channel is 0xHH (to be assigned by IANA)
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3.2. LI-LB Message Format
The format of an LI-LB Message 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 | Message Type | Operation | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Return Code | Cause Code | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sender's Handle |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TLV's |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: MPLS LI-LB Message Format
Version: The Version Number is currently 1. (Note: the version
number is to be incremented whenever a change is made that affects
the ability of an implementation to correctly parse or process the
request/response message. These changes include any syntactic or
semantic changes made to any of the fixed fields, or to any Type-
Length-Value (TLV) or sub-TLV assignment or format that is defined at
a certain version number. The version number may not need to be
changed if an optional TLV or sub-TLV is added.)
Message Type
Two message types are defined as shown below.
Message Type Description
------------ -------------
0x0 LI-LB request
0x1 LI-LB response
Operation
Four operations are defined as shown below. The operations can appear
in a Request or Response message.
Operation Description
--------- -------------
0x1 Lock
0x2 Unlock
0x3 Set_Loopback
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0x4 Unset_Loopback
Message Length
The total length of any included TLVs.
Sender's Handle
The Sender's Handle is filled in by the sender, and MUST be copied
unchanged by the receiver in the MPLS response message (if any).
There are no semantics associated with this handle, although a sender
may find this useful for matching up requests with replies.
Message ID
The Message ID is set by the sender of an MPLS request message. It
MUST be copied unchanged by the receiver in the MPLS response message
(if any). A sender SHOULD increment this value on each new message.
A retransmitted message SHOULD leave the value unchanged.
The Return code and Cause code only have meaning in a Response
message. In a request message the Return code and Cause code must be
set to zero and ignored on receipt. Return codes and cause codes are
described in the following Sections.
3.3. Return codes
Value Meaning
----- -------
0 Informational
1 Success
2 Failure
3.4. Cause codes
Value Meaning
----- -------
0 Success
1 Fail to match target MIP/MEP ID
2 Malformed LI-LB request received
3 One or more of the TLVs is/are unknown
4 Authentication failed
5 LSP/PW already locked
6 LSP/PW already unlocked
7 Fail to lock LSP/PW
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8 Fail to unlock LSP/PW
9 LSP/PW already in loopback mode
10 LSP/PW is not in loopback mode
11 Fail to set LSP/PW in loopback mode
12 Fail to remove LSP/PW from loopback mode
13 No label binding for received message
14 Authentication required but not received.
Note that in the case of cause code 3, the unknown TLV can also be
optionally included in the response. For failure responses with multiple
causes only the first cause code can be included.
3.5. Authentication TLV
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 = TBD | Length = 0xx |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Variable Length Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The PPP CHAP described in [9] will be used to authenticate the LI-LB
request.
The variable length value carried in the optional authentication TLV,
will include the Packet Format described in section 3.2 of [9].
The optional authentication TLV can be included in the MPLS OAM LSP
Ping echo messages containing a LI-LB request TLV or in the inband
LI-LB Message. When an authentication TLV is present in the Request
message the CHAP procedures described in section 3.2 of [9] MUST be
followed.
The CHAP packets will be transmitted by the authenticator using LI-LB
Request or response messages, responses to the authentication
protocol messages will be transmitted using LI-LB request or response
messages.
If the CHAP negotiation results in a failure, the authenticator or
the sender of the request message MUST stop requesting the LI-LB
function.
A receiver of an LI-LB request, MAY send an error "Authentication
required but not received", if the optional authentication TLV is not
included in the LI-LB request.
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3.6. LSP Ping Extensions
3.6.1. LI-LB Request TLV
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 = TBD | length = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Operation |
+-+-+-+-+-+-+
Operation Description
--------- -------------
0x1 Lock
0x2 Unlock
0x3 Set_Loopback
0x4 Unset_Loopback
A MEP includes a LI-LB Request TLV in the MPLS LSP Ping echo request
message to request the MEP on the other side of the LSP toperform
Lock/Unlock and Set/Unset Loopback operations. Only one LI-LB request
TLV can be present in an LSP Ping Echo request message.
3.6.2. LI-LB Response TLV
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 = TBD | Length = 0x3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Operation | ReturnCode | CauseCode |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Only one LI-LB response TLV can be present in an LSP Ping Echo
request message.
4. Loopback/Lock Operations
When performing a Lock or Loopback function, the reply to a message
MUST use the same method as the original message. That is, if a node
requests lock or loopback using LSP Ping then any replies to that
request must also use LSP Ping; if a node requests lock or loopback
using in-band, any replies to that request must use in-band. It is
permissible to use different methods for the lock and the loopback
functions on a given LSP. For example, a node can lock an LSP using
the LSP Ping method and then can loop the LSP using the in-band
method, or vice versa.
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An ACK response of a request will be a response message with return
code 1 (success) and cause code 0, while a NACK response will have a
return code 2 (failure) and the corresponding cause code.
4.1. Lock Request
Lock Request is used to request a MEP to take an LSP out of service
so that some form of maintenance can be done.
The receiver MEP MUST send either an ACK or a NAK response to the
sender MEP. Until the sender MEP receives an ACK, it MUST NOT assume
that the receiver MEP has taken the LSP out of service. A receiver
MEP sends an ACK only if it can successfully lock the LSP. Otherwise,
it sends a NAK.
The receiver MEP once locked, MUST discard all received traffic.
4.2. Unlock Request
The Unlock Request is sent from the MEP which has previously sent
lock request. Upon receiving the unlock request message, the receiver
MEP brings the LSP back in service.
The receiver MEP MUST send either an ACK or a NAK response to the
sender MEP. Until the sender MEP receives an ACK, it MUST NOT assume
that the LSP has been put back in service. A receiver MEP sends an
ACK only if the LSP has been unlocked, and unlock operation is
successful. Otherwise, it sends a NAK.
4.3. Loopback Request
When a MEP wants to put an LSP in loopback mode, it sends a Loopback
request message. The message can be intercepted by either a MIP or a
MEP depending on the MPLS TTL value. The receiver puts in
corresponding LSP in loopback mode.
The receiver MEP or MIP MUST send either an ACK or NAK response to
the sender MEP. An ACK response is sent if the LSP is successfully
put in loopback mode. Otherwise, a NAK response is sent. Until an ACK
response is received, the sender MEP MUST NOT assume that the LSP can
operate in loopback mode.
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4.4. Loopback Removal
When loopback mode operation of an LSP is no longer required, the MEP
that previously sent the Loopback request message sends another
Loopback Removal message. The receiver MEP changes the LSP from
loopback mode to normal mode of operation.
The receiver MEP or MIP MUST send either an ACK or NAK response to
the sender MEP. An ACK response is sent if the LSP is already in
loopback mode, and if the LSP is successfully put back in normal
operation mode. Otherwise, a NAK response is sent. Until an ACK
response is received, the sender MEP MUST NOT assume that the LSP is
put back in normal operation mode.
5. Data packets
Data packets sent from the sender MEP will be looped back to that
sender MEP. OAM packets not intercepted by TTL expiry will as well be
looped back. The use of data packets to measure packet loss, delay
and delay variation is outside the scope of this document.
6. Operation
6.1. General Procedures
When placing an LSP into Loopback mode, the operation MUST first be
preceded by a Lock operation.
When sending Loopback Request/Removal using LSP Ping or in-Band
messages the TTL of the topmost label is set as follows:-
If the target node is a MIP, the TTL MUST be set to the exact number
of hops required to reach that MIP.
If the target node is a MEP, the value MUST be set to at least the
number of hops required to reach that MEP. For most operations where
the target is a MEP, the TTL MAY be set to 255.
However, to remove a MEP from Loopback mode, the sending MEP MUST set
the TTL to the exact number of hops required to reach the MEP (if the
TTL were set higher, the Loopback removal message would be looped
back toward the sender).
6.2. Example Topology
The next four sections discuss the procedures for Locking, Unlocking,
setting an LSP into loopback, and removing the loopback. The
description is worded using an example. Assume an LSP traverses nodes
A <--> B <--> C <--> D. We will refer to the Maintenance Entities
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involved as MEP-A, MIP-B, MIP-C, and MEP-D respectively. Suppose a
maintenance operation invoked at MEP-A requires a loopback be set at
MIP-C. To invoke Loopack mode at MIP-C, A would first need to lock
the LSP. Then it may proceed to set the loopback at C. Following the
loopback operation, A would need to remove the loopback at C and
finally unlock the LSP.
The following sections describe MEP-A setting and unsetting a lock at
MEP-D and then setting and removing a loopback at MIP-C.
6.3. Locking an LSP
1. MEP-A sends an MPLS LSP Ping Echo request message with the Lock
TLV or an in-Band Lock request Message. Optionally, an authentication
TLV MAY be included.
2. Upon receiving the request message, D uses the received label
stack and the Target Stack FEC TLV as per [5]/source MEP-ID to
identify the LSP. If no label binding exists or there is no
associated LSP back to the originator, the event is logged.
Processing ceases. Otherwise the message is delivered to the target
MEP.
a. if the source MEP-ID does not match, the event is logged and
processing ceases.
b. if the target MEP-ID does not match, MEP-D sends a failure
response with cause code 1.
MEP-D then examines the message, and:
c. if the message is malformed, it sends a failure response with
cause code 2 back to MEP-A.
d. if message authentication fails, it MAY send a failure response
with cause code 4 back to MEP-A.
e. if any of the TLVs is not known, it sends a failure response with
cause code 3 back to MEP-A. It may also include the unknown TLVs.
f. if the LSP is already locked, it sends a response with
cause code 5 back to MEP-A.
g. if the LSP is not already locked and cannot be locked, it sends a
failure response with cause code 7 back to A.
h. if the LSP is successfully locked, it sends a success response
with cause code 0 (Success) back to MEP-A.
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The response is sent using an MPLS LSP Ping echo reply with a
response TLV or an in-Band Lock response message. An authentication
TLV MAY be included.
MEP-D will lock the LSP, resulting in that all traffic from D to A,
including all OAM traffic, stops.
a. MEP-A will detect a discontinuation in the OAM traffic, e.g. cv
and cc packets, but since it has been informed that the LSP will
be locked it will take no action(s).
b. When MEP-A receives the LI ACK, MEP-A discontinues sending
other OAM traffic, e.g. cv and cc packets. MEP-D will detect
this, but since it is in Locked state it will take no action.
6.4. Unlocking an LSP
1. MEP-A sends an MPLS Echo request message with the unLock TLV or an
in-Band unLock request Message. Optionally, an authentication TLV MAY
be included.
2. Upon receiving the unLock request message, D uses the received
label stack and target FEC/source MEP-ID as per [5] to identify the
LSP. If no label binding exists or there is no associated LSP back to
the originator, the event is logged. Processing ceases. Otherwise the
message is delivered to the target MEP.
a. if the source MEP-ID does not match, the event is logged and
processing ceases.
b. if the target MEP-ID does not match, MEP-D sends a failure
response with cause code 1.
MEP-D then examines the message, and:
c. if the message is malformed, it sends a failure response with
cause code 2 back to MEP-A.
d. if message authentication fails, it MAY send a failure response
with cause code 4 back to MEP-A.
e. if any of the TLVs is not known, it sends a failure response with
cause code 3 back to MEP-A. It may also include the unknown TLVs.
f. if the LSP is already unlocked, it sends a response with
cause code 6 back to MEP-A.
g. if the LSP is locked and cannot be unlocked, it sends a response
with cause code 8 back to MEP-A.
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h. if the LSP is successfully unlocked, it sends a success response
with cause code 0 (Success) back to MEP-A.
The response is sent using an MPLS LSP Ping echo reply with a
response TLV or an in-Band unlock response message. An authentication
TLV MAY be included.
6.5. Setting an LSP into Loopback mode
1. MEP-A sends an MPLS LSP Ping Echo request message with the
loopback TLV or an in-Band Loopback request message. Optionally, an
authentication TLV MAY be included.
2. Upon intercepting the MPLS Loopback message via TTL expiration, C
uses the received label stack and target FEC/source MEP-ID as per [5]
to identify the LSP.
If no label binding exists or there is no associated LSP back to the
originator, the event is logged. Processing ceases.
Otherwise the message is delivered to the target MIP/MEP - in this
case MIP-C.
a. if the source MEP-ID does not match, the event is logged and
processing ceases.
b. if the target MIP-ID does not match, MIP-C sends a failure
response with cause code 1.
MIP-C then examines the message, and:
c. if the message is malformed, it sends a failure response with
cause code 2 back to MEP-A.
d. if the message authentication fails, it sends a failure response
with cause code 4 back to MEP-A.
e. if any of the TLV is not known, C sends a failure response with
cause code 3 back to MEP-A. It may also include the unknown TLVs.
f. if the LSP is already in the requested loopback mode, it sends a
failure response with cause code 9 back to MEP-A.
g. if the LSP is not already in the requested loopback mode and that
loopback mode cannot be set, it sends a failure response with cause
code 11 back to MEP-A.
h. if the LSP is successfully programmed into the requested loopback
mode, it sends a success response with cause code 0 (Success) back to
MEP-A.
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The response is sent using an MPLS LSP Ping echo reply with a
response TLV or an in-Band Loopback response message. An
authentication TLV MAY be included.
6.6. Removing an LSP from Loopback mode
1. MEP-A sends a MPLS LSP Ping Echo request message with the Loopback
removal TLV or an in-Band Loopback removal request message.
Optionally, an authentication TLV MAY be included.
2. Upon intercepting the MPLS Loopback removal message via TTL
expiration, C uses the received label stack and the target FEC/source
MEP-ID as per [5] to identify the LSP.
If no label binding exists or there is no associated LSP back to
the originator, the event is logged. Processing ceases.
Otherwise the message is delivered to the target MIP/MEP - in this
case MIP-C.
a. if the source MEP-ID does not match, the event is logged and
processing ceases.
b. if the target MIP-ID does not match, MIP-C sends a failure
response with cause code 1 back to MEP-A.
MIP-C then examines the message, and:
c. if the message is malformed, it sends a failure response with
cause code 2 back to MEP-A.
d. if the message authentication fails, it sends a failure response
with cause code 4 back to MEP-A.
e. if any of the TLV is not known, C sends a failure response with
cause code 3 back to MEP-A. It may also include the unknown TLVs.
f. if the LSP is not in loopback mode, it sends a failure response
with cause code 10 back to MEP-A.
g. if the LSP loopback cannot be removed, it sends a failure response
with cause code 12 back to MEP-A.
h. if the LSP is successfully changed from loopback mode to normal
mode of operation, it sends a reply with cause code 0 (Success ) back
to MEP-A.
The response is sent using an MPLS LSP Ping echo reply with a
response TLV or an in-Band Loopback removal response message. An
authentication TLV MAY be included.
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7. Security Considerations
Security is addressed through the use of authentication TLV and the
the Challenge-Handshake Authentication protocol procedures described
in section [9].
8. IANA Considerations
8.1. Pseudowire Associated Channel Type
LI-LB OAM requires a unique Associated Channel Type which is assigned
by IANA from the Pseudowire Associated Channel Types Registry.
Registry:
Value Description TLV Follows Reference
----------- ----------------------- ----------- ---------
0xHHHH LI-LB No (Section 3.1)
8.2. New LSP Ping TLV types
IANA is requested to assign TLV type values to the following TLVs
from the "Multiprotocol Label Switching Architecture (MPLS) Label
Switched Paths (LSPs) Parameters - TLVs" registry, "TLVs and sub-
TLVs" sub-registry.
1. LI-LB Request TLV (See section 3.3.1)
2. LI-LB Response TLV (See section 3.3.2)
3. Authentication TLV (See section 3.3.3)
9. Acknowledgements
The authors would like to thank Loa Andersson for his valuable
comments.
10. References
10.1. Normative References
[1] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., and
S. Ueno, "Requirements of an MPLS Transport Profile", RFC 5654,
September 2009.
[2] Vigoureux, M., Ward, D., and M. Betts, "Requirements for
Operations, Administration, and Maintenance (OAM) in MPLS
Transport Networks", RFC 5860, May 2010.
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
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[4] K. Kompella, G. Swallow, "Detecting Multi-Protocol Label
Switched (MPLS) Data Plane Failures", RFC 4379, February 2006.
[5] N. Bahadur, et. al., "MPLS on-demand Connectivity Verification,
Route Tracing and Adjacency Verification", draft-ietf-mpls-tp-
on-demand-cv-00, work in progress, June 2010
[6] Bocci, M., Vigoureux, M., and S. Bryant, "MPLS Generic
Associated Channel", RFC 5586, June 2009.
[7] Bocci, M. and G. Swallow, "MPLS-TP Identifiers", draft-ietf-
mpls-tp-identifiers-01 (work in progress), June 2010.
[8] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., and
S.Ueno, "Requirements of an MPLS Transport Profile", RFC 5654,
September 2009.
[9] B. Lloyd, L&A, and W. Simpson, "PPP Authentication Protocols",
October 1992.
10.2. Informative References
[10] Nabil Bitar, et. al, "Requirements for Multi-Segment Pseudowire
Emulation Edge-to-Edge (PWE3) ", RFC5254, October 2008.
Author's Addresses
Sami Boutros
Cisco Systems, Inc.
Email: sboutros@cisco.com
Siva Sivabalan
Cisco Systems, Inc.
Email: msiva@cisco.com
Rahul Aggarwal
Juniper Networks.
EMail: rahul@juniper.net
Martin Vigoureux
Alcatel-Lucent.
Email: martin.vigoureux@alcatel-lucent.com
Xuehui Dai
ZTE Corporation.
Email: dai.xuehui@zte.com.cn
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George Swallow
Cisco Systems, Inc.
Email: swallow@cisco.com
David Ward
Juniper Networks.
Email: dward@juniper.net
Stewart Bryant
Cisco Systems, Inc.
Email: stbryant@cisco.com
Carlos Pignataro
Cisco Systems, Inc.
Email: cpignata@cisco.com
Eric Osborne
Cisco Systems, Inc.
Email: eosborne@cisco.com
Nabil Bitar
Verizon.
Email: nabil.bitar@verizon.com
Italo Busi
Alcatel-Lucent.
Email: italo.busi@alcatel-lucent.it
Lieven Levrau
Alcatel-Lucent.
Email: llevrau@alcatel-lucent.com
Laurent Ciavaglia
Alcatel-Lucent.
Email: laurent.ciavaglia@alcatel-lucent.com
Bo Wu
ZTE Corporation.
Email: wu.bo@zte.com.cn
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Jian Yang
ZTE Corporation.
Email: yang_jian@zte.com.cn
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