Network Working Group Sami Boutros (Ed.)
Internet Draft Siva Sivabalan (Ed.)
Intended status: Standards Track Cisco Systems, Inc.
Expires: September 1, 2011
Rahul Aggarwal (Ed.)
Juniper Networks, Inc.
Martin Vigoureux (Ed.)
Alcatel-Lucent
Xuehui Dai (Ed.)
ZTE Corporation
March 1, 2011
MPLS Transport Profile Lock Instruct and Loopback Functions
draft-ietf-mpls-tp-li-lb-01.txt
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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. LSP Ping Extensions.......................................8
3.3.1. Lock Request TLV.....................................8
3.3.2. Unlock Request TLV...................................8
3.3.3. Loopback Request TLV.................................8
3.3.4. Loopback Removal TLV.................................9
3.3.5. Response TLV.........................................9
3.3.6. Authentication TLV..................................10
4. Loopback/Lock Operations......................................10
4.1. Lock Request.............................................10
4.2. Unlock Request...........................................10
4.3. Loopback Request.........................................11
4.4. Loopback Removal.........................................11
5. Data packets..................................................11
6. Operation.....................................................11
6.1. General Procedures.......................................11
6.2. Example Topology.........................................12
6.3. Locking an LSP...........................................12
6.4. Unlocking an LSP.........................................13
6.5. Interoperability with Lock Instruct OAM function.........14
6.6. Setting an LSP into Loopback mode........................14
6.7. 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..............................................17
10. References...................................................17
10.1. Normative References....................................17
10.2. Informative References..................................17
Author's Addresses...............................................18
Full Copyright Statement.........................................19
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Intellectual Property Statement..................................20
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. We need to provide 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 the Generic Associated Channel (GACh) and over LSP-
Ping. LSP-Ping is possible to run over the GACh or when IP-addressing
is available it is possible to run it natively. The first two cases
will work for MPLS based Transport Networks without IP-addressing.
To describe the loopback functionality, let us assume a bi-
directional LSP in a MPLS based Transport Network A <---> B <---> C
<---> D where A, B, C, and D are MPLS capable nodes. Also, let us
assume that the network operator requires C to loop, back to A, so
that all the test data packets sent from A over that LSP. In this
example, A and D acts as Maintenance End Points (MEPs) and C acts as
a Maintenance Intermediate Point (MIP). The operator can setup the
LSP into loopback mode such that C loops all MPLS encapsulated
packets (regardless of whether they are data or control packets) that
A as an ingress LSR puts on the LSP back to A. The packets MUST NOT
be forwarded towards D. Similarly, any traffic received by C from the
reverse direction MUST be dropped.
For any LSP in a MPLS based Transport Network the operator must take
the LSP out of service before setting up the LSP in loopback mode.
This is accomplished by the MEP establishing the loopback first
sending a Lock command to the remote MEP(s). In the case above, A
sends a Lock request message along the LSP and destined to D to lock
the LSP. The message will be intercepted by D since it is at the end
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of the LSP. D responds to the lock request with a reply message
specifying whether it can take the LSP out of service or not.
In order to set the LSP in loopback mode, A sends a Loopback request
message to the MIP or MEP where the loopback is to be enabled. In the
above example, the MPLS TTL value is set so that the message will be
intercepted by C.
The request message contains a Loopback request to instruct C to
operate an indicated LSP in Loopback mode. C responds to the Loopback
request with a reply message back to A to indicate whether or not it
has successfully set the LSP into the loopback mode.
If the loopback cannot be set, the reply message would contain an
error code. Upon receiving a reply with an error code to the loopback
request, A logs the event and takes further reporting actions as
necessary. If the LSP was previously locked, A sends another request
message to D to unlock it.
If the loopback request can be performed, the input LSP from the
direction of A is directly cross-connected to the output LSP towards
A. All the packets generated by node A (data and control) are looped
back at C, excepting the case of TTL expiration.
When the loopback operation is no longer required, A sends a request
message to remove the loopback and thus restore the LSP to its
original forwarding state. In this example the MPLS TTL is set such
that this message is intercepted by C. It is expected that C sends a
reply back to A to with a return code either ACKing or NAK the
loopback removal request. Upon getting an ACK response to loopback
mode removal request, A sends another request message to unlock the
LSP. The packet is intercepted by D as it is at the end of the LSP.
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.
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Conventions used in this document
In examples, "C:" and "S:" indicate lines sent by the client and
server respectively.
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].
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
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|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)
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
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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
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.
Return code
Value Meaning
----- -------
0 Informational
1 Success
2 Failure
Cause code
Value Meaning
----- -------
0 No cause code
1 Fail to match target MIP/MEP ID
2 Malformed 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
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.
3.3. LSP Ping Extensions
3.3.1. Lock 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 = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A MEP includes a Lock Request TLV in the MPLS LSP Ping echo request
message to request the MEP on the other side of the LSP to take the
LSP out of service.
3.3.2. Unlock 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 = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Unlock Request TLV is sent from the MEP which has previously sent
lock request. Upon receiving the LSP Ping Echo request message with
the unlock request TLV, the receiver MEP brings the LSP back in
service.
3.3.3. Loopback 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 = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
When a MEP wants to put an LSP in loopback mode, it sends a MPLS LSP
Ping echo request message with Loopback Request TLV. The message can
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be intercepted by either a MIP or a MEP depending on the MPLS TTL
value. The receiver puts in corresponding LSP in loopback mode.
3.3.4. Loopback Removal 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 = 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
When loopback mode operation of an LSP is no longer required, the MEP
that previously sent the MPLS LSP Ping echo request message with a
loopback TLV, sends another MPLS LSP Ping echo request message with a
Loopback Removal TLV. The receiver MEP changes the LSP from loopback
mode to normal mode of operation.
3.3.5. 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 = 0x1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|ReturnCode |
+-+-+-+-+-+-+-+
Return code
Value Meaning
----- -------
0 Success
1 Fail to match target MIP/MEP ID
2 Malformed loopback 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
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
Note that in the case of error code 3, the unknown TLV can also be
optionally included in the response TLV.
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3.3.6. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Mechanisms similar to PPP Chap can be used to authenticate the
Loopback request. A variable length key can be carried in an optional
authentication TLV which can be included in the MPLS OAM LSP Ping
echo request message containing a loopback request TLV or the LI-LB
Message. The use of authentication key is outside the scope of the
document.
4. Loopback/Lock Operations
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.
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.
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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.
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. 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.
Sending LSP Ping Echo Request message with Loopback Request/Removal
or in-Band Loopback Request/Removal Message
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.
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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). It is RECOMMENDED that the TTL be set to the
exact number of hops required to reach the MEP.
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
involved as MEP-A, MIP-B, MIP-C, and MEP-D respectively. Suppose a
maintenance operation invoked at node A requires a loopback be set at
node C. To invoke Loopack mode at node 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 FEC/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 response with
error code 1.
MEP-D then examines the message, and:
c. if the message is malformed, it sends a response with error code 2
back to MEP-A.
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d. if message authentication fails, it MAY send a response with error
code 4 back to MEP-A.
e. if any of the TLVs is not known, it sends a response with error
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
error code 5 back to MEP-A.
g. if the LSP is not already locked and cannot be locked, it sends a
response with error code 7 back to A.
h. if the LSP is successfully locked, it sends a response with error
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 Lock response message. An authentication
TLV MAY be included.
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 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 response with
error code 1.
MEP-D then examines the message, and:
c. if the message is malformed, it sends a response with error code 2
back to MEP-A.
d. if message authentication fails, it MAY send a response with error
code 4 back to MEP-A.
e. if any of the TLVs is not known, it sends a response with error
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
error code 6 back to MEP-A.
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g. if the LSP is locked and cannot be unlocked, it sends a response
with error code 8 back to MEP-A.
h. if the LSP is successfully unlocked, it sends a response with
error 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. Interoperability with Lock Instruct OAM function
a. Upon receiving a lock instruct MEP-D will lock the LSP,
resulting in that all traffic from D to A, including OAM, stops.
b. MEP-A will detect a discontinuation in the OAM traffic, e.g. cv
and cc, but since it has been informed that the LSP will be
locked it will take no action(s).
c. MEP-D will send an LI Ack, and be prepared that all traffic,
including OAM will stop
d. When MEP-A receives the LI ACK, MEP-A discontinues sending OAM
traffic.
e. MEP-D will detect this, but since it is in Locked state it will
take no action.
6.6. 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 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 response with
error code 1.
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MIP-C then examines the message, and:
c. if the message is malformed, it sends a response with error code 2
back to MEP-A.
d. if the message authentication fails, it sends a response with
error code 4 back to MEP-A.
e. if any of the TLV is not known, C sends a response with error 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
response with error 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 response with error code 11
back to MEP-A.
h. if the LSP is successfully programmed into the requested loopback
mode, it sends a response with error 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 response message. An
authentication TLV MAY be included.
6.7. 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 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 response with
error code 1 back to MEP-A.
MIP-C then examines the message, and:
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c. if the message is malformed, it sends a response with error code 2
back to MEP-A.
d. if the message authentication fails, it sends a response with
error code 4 back to MEP-A.
e. if any of the TLV is not known, C sends a response with error 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 response with error
code 10 back to MEP-A.
g. if the LSP loopback cannot be removed, it sends a response with
error 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 error 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.
7. Security Considerations
The security considerations for the authentication TLV need further
study.
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.
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1. Lock Request TLV (See section 3.3.1)
2. Unlock Request TLV (See section 3.3.2)
3. Loopback Request TLV (See section 3.3.3)
4. Loopback Removal TLV (See section 3.3.4)
5. Response TLV (See section 3.3.5)
6. Authentication TLV (See section 3.3.6)
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.
[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-nitinb-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.
10.2. Informative References
[9] Nabil Bitar, et. al, "Requirements for Multi-Segment Pseudowire
Emulation Edge-to-Edge (PWE3) ", RFC5254, October 2008.
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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
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
Nabil Bitar
Verizon.
Email: nabil.bitar@verizon.com
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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
Jian Yang
ZTE Corporation.
Email: yang_jian@zte.com.cn
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