draft-ietf-mpls-tp-li-lb-08.txt   rfc6435.txt 
Network Working Group Sami Boutros (Ed.) Internet Engineering Task Force (IETF) S. Boutros, Ed.
Internet Draft Siva Sivabalan (Ed.) Request for Comments: 6435 S. Sivabalan, Ed.
Intended status: Standards Track Cisco Systems, Inc. Updates: 6371 Cisco Systems, Inc.
Updates: 6371 (if approved) Category: Standards Track R. Aggarwal, Ed.
Expires: April 24, 2012 Rahul Aggarwal (Ed.) ISSN: 2070-1721 Arktan, Inc.
Arktan, Inc. M. Vigoureux, Ed.
Martin Vigoureux (Ed.)
Alcatel-Lucent Alcatel-Lucent
X. Dai, Ed.
Xuehui Dai (Ed.)
ZTE Corporation ZTE Corporation
November 2011
October 24, 2011 MPLS Transport Profile Lock Instruct and Loopback Functions
MPLS Transport Profile lock Instruct and Loopback Functions
draft-ietf-mpls-tp-li-lb-08.txt
Abstract Abstract
Two useful Operations, Administration, and Maintenance (OAM) Two useful Operations, Administration, and Maintenance (OAM)
functions in a transport network are "lock" and "loopback". The lock functions in a transport network are "lock" and "loopback". The lock
function enables an operator to lock a transport path such that it function enables an operator to lock a transport path such that it
does not carry client traffic, but can continue to carry OAM messages does not carry client traffic, but can continue to carry OAM messages
and may carry test traffic. The loopback function allows an operator and may carry test traffic. The loopback function allows an operator
to set a specific node on the transport path into loopback mode such to set a specific node on the transport path into loopback mode such
that it returns all received data. that it returns all received data.
This document specifies the lock function for MPLS networks and This document specifies the lock function for MPLS networks and
describes how the loopback function operates in MPLS networks. describes how the loopback function operates in MPLS networks.
This document updates RFC 6371 section 7.1.1 and 7.1.2. This document updates Sections 7.1.1 and 7.1.2 of RFC 6371.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the Status of This Memo
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This is an Internet Standards Track document.
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
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Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
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Internet Standards is available in Section 2 of RFC 5741.
The list of current Internet-Drafts can be accessed at Information about the current status of this document, any errata,
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Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
1. Introduction 1. Introduction
Two useful Operations, Administration, and Maintenance (OAM) Two useful Operations, Administration, and Maintenance (OAM)
functions in a transport network are "lock" and "loopback". This functions in a transport network are "lock" and "loopback". This
document discusses these functions in the context of MPLS networks. document discusses these functions in the context of MPLS networks.
- The lock function enables an operator to lock a transport path such - The lock function enables an operator to lock a transport path
that it does not carry client traffic. As per RFC 5860 [1], lock is such that it does not carry client traffic. As per RFC 5860 [1],
an administrative state in which it is expected that no client lock is an administrative state in which it is expected that no
traffic may be carried. However, test traffic and OAM messages can client traffic may be carried. However, test traffic and OAM
still be mapped onto the locked transport path. The lock function messages can still be mapped onto the locked transport path. The
may be applied to to Label Switched Paths (LSPs), Pseudowires (PWs) lock function may be applied to the Label Switched Paths (LSPs),
(including multi-segment Pseudowires) (MS-PWs), and bidirectional Pseudowires (PWs) (including multi-segment Pseudowires) (MS-PWs),
MPLS Sections as defined in RFC 5960 [9]). and bidirectional MPLS Sections as defined in RFC 5960 [9]).
- The loopback function allows an operator to set a specific node on - The loopback function allows an operator to set a specific node on
a transport path into loopback mode such that it returns all a transport path into loopback mode such that it returns all
received data. Loopback can be applied at a Maintenance Entity received data. Loopback can be applied at a Maintenance Entity
Group End Point (MEP) or a Maintenance Entity Group Intermediate Group End Point (MEP) or a Maintenance Entity Group Intermediate
Point (MIP) on a co-routed bidirectional LSP, on a PW, or on an Point (MIP) on a co-routed bidirectional LSP, on a PW, or on a
bidirectional MPLS Section. It can also be applied at a MEP on an bidirectional MPLS Section. It can also be applied at a MEP on an
associated bidirectional LSP. associated bidirectional LSP.
Loopback is used to test the integrity of the transport path to and Loopback is used to test the integrity of the transport path to
from the node that is performing loopback. It requires that the and from the node that is performing loopback. It requires that
transport is locked and that a MEP on the transport path sends test the transport path be locked and that a MEP on the transport path
data which it also validates on receipt. send test data that it also validates on receipt.
This document specifies the lock function for MPLS networks and This document specifies the lock function for MPLS networks and
describes how the loopback function operates in MPLS networks. describes how the loopback function operates in MPLS networks.
This document updates RFC 6371 section 7.1.1 [6]. 1.1. Updates RFC 6371
1.1. Updates RFC 6371
This document updates section 7.1.1 and 7.1.2 of RFC 6371 [6]. This document updates Sections 7.1.1 and 7.1.2 of RFC 6371 [6].
That framework makes the assumption that the Lock Instruct message is The framework in RFC 6371 makes the assumption that the Lock Instruct
used to independently enable locking and requires a response message. message is used to independently enable locking and requires a
response message.
The mechanism defined in this document requires that a lock The mechanism defined in this document requires that when a lock
instruction is sent by management to both ends of the locked instruction is sent by management to both ends of the locked
transport path and that the Lock Instruct message does not require a transport path, the Lock Instruct message does not require a
response. response.
2. Terminology and Conventions 2. Terminology and Conventions
2.1. Conventions Used in This Document 2.1. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [2]. document are to be interpreted as described in RFC 2119 [2].
2.2. Acronyms and Terms 2.2. Acronyms and Terms
ACH: Associated Channel Header ACH: Associated Channel Header
LI: Lock Instruct
MEG: Maintenance Entity Group MEG: Maintenance Entity Group
MEP: Maintenance Entity Group End Point MEP: Maintenance Entity Group End Point
MIP: Maintenance Entity Group Intermediate Point MIP: Maintenance Entity Group Intermediate Point
MPLS-TP: MPLS Transport Profile MPLS-TP: MPLS Transport Profile
MPLS-TP LSP: Bidirectional Label Switch Path NMS: Network Management System
TLV: Type Length Value TLV: Type Length Value
TTL: Time To Live Transport path: MPLS-TP LSP or PW
LI: Lock Instruct
NMS: Network Management System
Transport path: MPLS-TP LSP or MPLS PW
3. Lock Function TTL: Time To Live
Lock is used to request a MEP to take a transport path out of service 3. Lock Function
for administrative reasons. For example, Lock can be used to allow
some form of maintenance to be done for a transport path. Lock is
also a prerequisite of the Loopback function described in Section 4.
The NMS or a management process initiates a Lock by sending a Lock Lock is used to request that a MEP take a transport path out of
command to a MEP. The MEP takes the transport path out of service, service for administrative reasons. For example, Lock can be used to
that is, it stops injecting or forwarding traffic onto the transport allow some form of maintenance to be done for a transport path. Lock
path. is also a prerequisite of the loopback function described in Section
4. The NMS or a management process initiates a Lock by sending a
Lock command to a MEP. The MEP takes the transport path out of
service, that is, it stops injecting or forwarding traffic onto the
transport path.
To properly lock a transport path (for example, to ensure that a To properly lock a transport path (for example, to ensure that a
loopback test can be performed), both directions of the transport loopback test can be performed), both directions of the transport
path must be taken out of service so a Lock command is sent to the path must be taken out of service; therefore, a Lock command is sent
MEPs at both ends of the path. This ensures that no traffic is sent to the MEPs at both ends of the path. This ensures that no traffic
in either direction. Thus, the Lock function can be realized entirely is sent in either direction. Thus, the lock function can be realized
using the management plane. entirely using the management plane.
However, dispatch of messages in the management plane to the two MEPs However, dispatch of messages in the management plane to the two MEPs
may present coordination challenges. It is desirable that the lock be may present coordination challenges. It is desirable that the lock
achieved in a coordinated way within a tight window, and this may be be achieved in a coordinated way within a tight window, and this may
difficult with a busy management plane. In order to provide be difficult with a busy management plane. In order to provide
additional coordination, an LI OAM message can additionally be sent. additional coordination, an LI OAM message can also be sent. A MEP
A MEP locks a transport path when it receives a command from a locks a transport path when it receives a command from a management
management process or when it receives an LI message as described in process or when it receives an LI message as described in Section 6.
Section 6.
This document defines an LI message for MPLS OAM. The LI message is This document defines an LI message for MPLS OAM. The LI message is
based on a new ACH Type as well as an existing TLV. This is a common based on a new ACH Type as well as an existing TLV. This is a common
mechanism applicable to lock LSPs, PWs, and bidirectional MPLS mechanism applicable to lock LSPs, PWs, and bidirectional MPLS
Sections. Sections.
4. Loopback Function 4. Loopback Function
This section provides a description of the Loopback function within This section provides a description of the loopback function within
an MPLS network. This function is achieved through management an MPLS network. This function is achieved through management
commands and so there is no protocol specification necessary. commands, so there is no protocol specification necessary. However,
However, the Loopback function is dependent on the Lock function and the loopback function is dependent on the lock function, so it is
so it is appropriate to describe it in this document. appropriate to describe it in this document.
The Loopback function is used to test the integrity of a transport The loopback function is used to test the integrity of a transport
path from a MEP up any other node in the same MEG. This is achieved path from a MEP up any other node in the same MEG. This is achieved
by setting the target node into loopback mode, and transmitting a by setting the target node into loopback mode, and transmitting a
pattern of test data from the MEP. The target node loops all received pattern of test data from the MEP. The target node loops all
data back toward the originator, and the MEP extracts the test data received data back toward the originator, and the MEP extracts the
and compares it with what it sent. test data and compares it with what it sent.
Loopback is a function that enables a receiving MEP or MIP to return Loopback is a function that enables a receiving MEP or MIP to return
traffic to the sending MEP when in the loopback state. This state traffic to the sending MEP when in the loopback state. This state
corresponds to the situation where, at a given node, a forwarding corresponds to the situation where, at a given node, a forwarding
plane loop is configured and the incoming direction of a transport plane loop is configured, and the incoming direction of a transport
path is cross-connected to the outgoing reverse direction. Therefore, path is cross-connected to the outgoing reverse direction.
except in the case of early TTL expiry, traffic sent by the source Therefore, except in the case of early TTL expiry, traffic sent by
will be received by that source. the source will be received by that source.
Data plane loopback is an out-of-service function, as required in Data-plane loopback is an out-of-service function, as required in
section 2.2.5 of RFC 5860 [1]. This function loops back all traffic Section 2.2.5 of RFC 5860 [1]. This function loops back all traffic
(including user data and OAM). The traffic can be originated from one (including user data and OAM). The traffic can be originated from
internal point at the ingress of a transport path within an interface one internal point at the ingress of a transport path within an
or inserted from input port of an interface using an external test interface or inserted from an input port of an interface using
equipment. The traffic is looped back unmodified (other than normal external test equipment. The traffic is looped back unmodified
per hop processing such as TTL decrement) in the direction of the (other than normal per-hop processing such as TTL decrement) in the
point of origin by an interface at either an intermediate node or a direction of the point of origin by an interface at either an
terminating node. intermediate node or a terminating node.
It should be noted that data plane loopback function itself is It should be noted that the data-plane loopback function itself is
applied to data plane loopback points residing on different applied to data-plane loopback points residing on different
interfaces from MIPs/MEPs. All traffic (including both payload and interfaces from MIPs/MEPs. All traffic (including both payload and
OAM) received on the looped back interface is sent on the reverse OAM) received on the looped back interface is sent on the reverse
direction of the transport path. direction of the transport path.
For data plane loopback at an intermediate point in a transport For data-plane loopback at an intermediate point in a transport path,
path, the loopback needs to be configured to occur at either the the loopback needs to be configured to occur at either the ingress or
ingress or egress interface. This is done using management. egress interface. This is done using management.
The management plane can be used to configure the Loopback function. The management plane can be used to configure the loopback function.
The management plane must ensure that the two MEPs are locked before The management plane must ensure that the two MEPs are locked before
it requests setting MEP or MIP in the loopback state. it requests setting MEP or MIP in the loopback state.
The nature of test data and the use of loopback traffic to measure The nature of test data and the use of loopback traffic to measure
packet loss, delay, and delay variation is outside the scope of this packet loss, delay, and delay variation are outside the scope of this
document. document.
4.1. Operational Prerequisites 4.1. Operational Prerequisites
Obviously, for the Loopback function to operate, there are several Obviously, for the loopback function to operate, there are several
prerequisites: prerequisites:
- There must be a return path, so transport path under test must be - There must be a return path, so the transport path under test must
bidirectional. be bidirectional.
- The node in loopback mode must be on both the forward and return - The node in loopback mode must be on both the forward and return
paths. This is possible for all MEPs and MIPs on a co-routed paths. This is possible for all MEPs and MIPs on a co-routed
bidirectional LSP, on a PW, or on a bidirectional MPLS Section, but bidirectional LSP, on a PW, or on a bidirectional MPLS Section,
is only possible on for MEPs on associated bidirectional LSPs. but it is only possible for MEPs on associated bidirectional LSPs.
- The transport path cannot deliver client data when one of its nodes - The transport path cannot deliver client data when one of its
is in loopback mode, so it is important that the transport path is nodes is in loopback mode, so it is important that the transport
locked before loopback is enabled. path be locked before loopback is enabled.
- Management plane coordination between the node in loopback mode and - Management-plane coordination between the node in loopback mode
the MEP sending test data is required. The MEP must not send test and the MEP sending test data is required. The MEP must not send
data until loopback has been properly configured because this would test data until loopback has been properly configured because this
result in the test data continuing toward the destination. would result in the test data continuing toward the destination.
- The TTL of the test packets must be set sufficiently large to - The TTL of the test packets must be set sufficiently large to
account for both directions of the transport path under test account for both directions of the transport path under test;
otherwise the packets will not be returned to the originating MEP. otherwise, the packets will not be returned to the originating
MEP.
- OAM messages intended for delivery to nodes along the transport - OAM messages intended for delivery to nodes along the transport
path under test can be delivered by correct TTL expiry. However, path under test can be delivered by correct TTL expiry. However,
OAM messages cannot be delivered to points beyond the loopback node OAM messages cannot be delivered to points beyond the loopback
until the loopback condition is lifted. node until the loopback condition is lifted.
5. Lock Instruct Message 5. Lock Instruct Message
5.1. Message Identification 5.1. Message Identification
The Lock Instruct Message is carried in the Associated Channel Header The Lock Instruct message is carried in the Generic ACH described in
(ACh) described in [4]. it is identified by a new PW ACh Type of 0xHH [4]. It is identified by a new PW ACH Type of 0x0026.
(to be assigned by IANA).
5.2. LI Message Format 5.2. LI Message Format
The format of an LI Message is shown below. The format of an LI message is shown below.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vers | Reserved | Refresh Timer | | Vers | Reserved | Refresh Timer |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MEP Source ID TLV | | MEP Source ID TLV |
~ ~ ~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: MPLS Lock Instruct Message Format Figure 1: MPLS Lock Instruct Message Format
Version: The Version Number is currently 1. (Note: the version Version: The Version number is currently 1. (Note: the version
number is to be incremented whenever a change is made that affects number is to be incremented whenever a change is made that affects
the ability of an implementation to correctly parse or process the the ability of an implementation to correctly parse or process the
message. These changes include any syntactic or semantic changes made message. These changes include any syntactic or semantic changes
to any of the fixed fields, or to any Type-Length-Value (TLV) or sub- made to any of the fixed fields, or to any Type-Length-Value (TLV) or
TLV assignment or format that is defined at a certain version number. sub- TLV assignment or format that is defined at a certain version
The version number may not need to be changed if an optional TLV or number. The version number may not need to be changed if an optional
sub-TLV is added.) TLV or sub-TLV is added.)
Reserved: The reserved field MUST be set to zero on transmission and Reserved: The Reserved field MUST be set to zero on transmission and
SHOULD be ignored on receipt. SHOULD be ignored on receipt.
Refresh Timer: The maximum time between successive LI messages Refresh Timer: The Refresh Timer is the maximum time between
specified in seconds. The default value is 1. The value 0 is not successive LI messages specified in seconds. The default value is 1.
permitted. When a lock is applied, a refresh timer is chosen. This The value 0 is not permitted. When a lock is applied, a refresh
value MUST NOT be changed for the duration of that lock. A node timer is chosen. This value MUST NOT be changed for the duration of
receiving a LI message with a changed refresh timer MAY ignore the that lock. A node receiving an LI message with a changed refresh
new value and continue to apply the old value. timer MAY ignore the new value and continue to apply the old value.
MEP Source ID TLV: This is one of the three MEP Source ID TLVs MEP Source ID TLV: This is one of the three MEP Source ID TLVs
defined in [3] and identifies the MEP that originated the LI message. defined in [3] and identifies the MEP that originated the LI message.
6. Operation of the Lock Function 6. Operation of the Lock Function
6.1. Locking a Transport Path 6.1. Locking a Transport Path
When a MEP receives a Lock command from an NMS or through some other When a MEP receives a Lock command from an NMS or through some other
management process, it MUST take the transport path out of service. management process, it MUST take the transport path out of service.
That is, it MUST stop injecting or forwarding traffic onto the LSP, That is, it MUST stop injecting or forwarding traffic onto the LSP,
PW, or bidirectional Section that has been locked. PW, or bidirectional Section that has been locked.
As soon as the transport path has been locked, the MEP MUST send an If rapid coordination of lock state is to be achieved (as described
LI message targeting the MEP at the other end of the locked transport in Section 3) then as soon as the transport path has been locked, the
path. The source MEP MUST set the Refresh Timer value in the LI MEP MUST send an LI message targeting the MEP at the other end of the
message and MUST retransmit the LI message at the frequency indicated locked transport path. In this case, the source MEP MUST set the
by the value set. Refresh Timer value in the LI message and MUST retransmit the LI
message at the frequency indicated by the value set.
When locking a transport path, the NMS or management process is When locking a transport path, the NMS or management process is
required to send a Lock command to both ends of the transport path. required to send a Lock command to both ends of the transport path.
Thus a MEP may receive either the management command or an LI message Thus, a MEP may receive either the management command or an LI
first. A MEP MUST take the transport path out of service immediately message first. A MEP MUST take the transport path out of service
in either case, but only sends LI messages itself after it has immediately in either case, but sends LI messages itself after it has
received a management lock command. Thus, a MEP is locked if either received a management Lock command. Thus, a MEP is locked if either
Lock was requested by management (and, as a result, the MEP is Lock was requested by management (and, as a result, the MEP is
sending LI messages), or it is receiving LI messages from the remote sending LI messages) or it is receiving LI messages from the remote
MEP. MEP.
Note that a MEP that receives an LI message MUST identify the correct Note that a MEP that receives an LI message MUST identify the correct
transport path and validate the message. The label stack on the transport path and validate the message. The label stack on the
received message is used to identify the transport path to be locked: received message is used to identify the transport path to be locked:
- If no matching label binding exists then there is no corresponding - If no matching label binding exists, then there is no
transport path and the received LI message is in error. corresponding transport path and the received LI message is in
error.
- If the transport path can be identified, but there is no return - If the transport path can be identified, but there is no return
path (for example, the transport path was unidirectional) then the path (for example, the transport path was unidirectional) then
lock cannot be applied by the receiving MEP. (obviously) the receiving MEP cannot apply a lock to the return
path.
- If the transport path is suitable for locking but the source MEP-ID - If the transport path is suitable for locking but the Source MEP-
identifies an unexpected MEP for the MEG to which the receiving MEP ID identifies an unexpected MEP for the MEG to which the receiving
belongs, the received LI message is in error. MEP belongs, the received LI message is in error.
When an errored LI message is received, the receiving MEP MUST NOT When an errored LI message is received, the receiving MEP MUST NOT
apply a lock. A MEP receiving errored LI messages SHOULD perform apply a lock. A MEP receiving errored LI messages SHOULD perform
local diagnostic actions (such as counting the messages) and MAY local diagnostic actions (such as counting the messages) and MAY log
log the messages. the messages.
A MEP keeps a transport path locked as long as it is either receiving A MEP keeps a transport path locked as long as it is either receiving
the periodic LI messages or has an in-force Lock command from the periodic LI messages or has an in-force Lock command from
management. (see Section 6.2 for an explanation of unlocking a MEP). management (see Section 6.2 for an explanation of unlocking a MEP).
Note that in some scenarios (such as the use of loopback as described Note that in some scenarios (such as the use of loopback as described
in Section 4) LI messages will not continue to be delivered on a in Section 4), LI messages will not continue to be delivered on a
locked transport path. This is why a transport path is considered locked transport path. This is why a transport path is considered
locked while there is an in-force Lock command from a management locked while there is an in-force Lock command from a management
process regardless of whether LI messages are being received. process regardless of whether LI messages are being received.
6.2. UnLocking a Transport Path 6.2. Unlocking a Transport Path
Unlock is used to request a MEP to bring the previously locked Unlock is used to request that a MEP bring the previously locked
transport path back in service. transport path back in service.
When a MEP receives an Unlocked command from a management process it When a MEP receives an Unlock command from a management process, it
MUST cease sending LI messages. However, as described in Section 6.1, MUST cease sending LI messages. However, as described in Section
if the MEP is still receiving LI messages, the transport path MUST 6.1, if the MEP is still receiving LI messages, the transport path
remain out of service. Thus, to unlock a transport path, the MUST remain out of service. Thus, to unlock a transport path, the
management process has to send an Unlock command to the MEPs at management process has to send an Unlock command to the MEPs at both
both ends. ends.
When a MEP has been unlocked and has not received an LI message for a When a MEP has been unlocked and has not received an LI message for a
multiple of 3.5 times the Refresh Timer on the LI message (or has multiple of 3.5 times the Refresh Timer on the LI message (or has
never received an LI message), the MEP unlocks the transport path and never received an LI message), the MEP unlocks the transport path and
puts it back into service. puts it back into service.
7. Security Considerations 7. Security Considerations
MPLS-TP is a subset of MPLS and so builds upon many of the aspects of MPLS-TP is a subset of MPLS and builds upon many of the aspects of
the security model of MPLS. MPLS networks make the assumption that it the security model of MPLS. MPLS networks make the assumption that
is very hard to inject traffic into a network, and equally hard to it is very hard to inject traffic into a network, and it is equally
cause traffic to be directed outside the network. For more hard to cause traffic to be directed outside the network. For more
information on the generic aspects of MPLS security, see [7]. information on the generic aspects of MPLS security, see [7].
This document describes a protocol carried in the G-ACh [4], and so This document describes a protocol carried in the G-ACh [4], so it is
is dependent on the security of the G-ACh, itself. The G-ACh is a dependent on the security of the G-ACh, itself. The G-ACh is a
generalization of the Associated Channel defined in [8]. Thus, this generalization of the Pseudowire Associated Channel defined in [8].
document relies heavily on the security mechanisms provided for the Thus, this document relies heavily on the security mechanisms
Associated Channel and described in [4] and [8]. provided for the Associated Channel as described in [4] and [8].
A specific concern for the G-ACh is that is can be used to provide a A specific concern for the G-ACh is that is can be used to provide a
covert channel. This problem is wider than the scope of this covert channel. This problem is wider than the scope of this
document and does not need to be addressed here, but it should be document and does not need to be addressed here, but it should be
noted that the channel provides end-to-end connectivity and SHOULD noted that the channel provides end-to-end connectivity and SHOULD
NOT be policed by transit nodes. Thus, there is no simple way of NOT be policed by transit nodes. Thus, there is no simple way to
preventing any traffic being carried in the G-ACh between consenting prevent traffic from being carried in the G-ACh between consenting
nodes. nodes.
A good discussion of the data plane security of an associated channel A good discussion of the data-plane security of an associated channel
may be found in [5]. That document also describes some mitigation may be found in [5]. That document also describes some mitigation
techniques. techniques.
It should be noted that the G-ACh is essentially connection-oriented It should be noted that the G-ACh is essentially connection-oriented,
so injection or modification of control messages specified in this so injection or modification of control messages specified in this
document require the subversion of a transit node. Such subversion is document requires the subversion of a transit node. Such subversion
generally considered hard in MPLS networks, and impossible to protect is generally considered hard in MPLS networks, and impossible to
against at the protocol level. Management level techniques are more protect against at the protocol level. Management-level techniques
appropriate. are more appropriate.
8. IANA Considerations 8. IANA Considerations
8.1. Pseudowire Associated Channel Type 8.1. Pseudowire Associated Channel Type
LI OAM requires a unique Associated Channel Type which is assigned by LI OAM requires a unique Associated Channel Type that has been
IANA from the Pseudowire Associated Channel Types Registry. assigned by IANA in the "Pseudowire Associated Channel Types"
registry.
Registry: Registry:
Value Description TLV Follows Reference Value Description TLV Follows Reference
----------- ----------------------- ----------- --------- ----------- ----------------------- ----------- ---------
0xHH LI No [This.I-D] 0x0026 LI No [RFC6435]
9. Acknowledgements 9. Acknowledgements
The authors would like to thank Loa Andersson, Yoshinori Koike, The authors would like to thank Loa Andersson, Yoshinori Koike,
Alessandro D'Alessandro Gerardo, Shahram Davari, Greg Mirsky, Yaacov Alessandro D'Alessandro Gerardo, Shahram Davari, Greg Mirsky, Yaacov
Weingarten, Liu Guoman, Matthew Bocci, and Adrian Farrel for their Weingarten, Liu Guoman, Matthew Bocci, Adrian Farrel, and Jia He for
valuable comments. their valuable comments.
10. References
10.1. Normative References
[1] Vigoureux, M., Ward, D., and M. Betts, "Requirements for
Operations, Administration, and Maintenance (OAM) in MPLS
Transport Networks", RFC 5860, May 2010.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[3] D. Allan, et. al., Proactive Connectivity Verification,
Continuity Check and Remote Defect indication for MPLS
Transport Profile draft-ietf-mpls-tp-cc-cv-rdi-06, work in
progress, June 2010
[4] Bocci, M., Vigoureux, M., and S. Bryant, "MPLS Generic
Associated Channel", RFC 5586, June 2009.
[5] T. Nadeau, C. Pignataro, "Pseudowire Virtual Circuit 10. References
Connectivity Verification (VCCV): A Control Channel for
Pseudowires", RFC 5085, Dec 2007.
[6] Busi, I. and Allan, D., "Operations, Administration, and 10.1. Normative References
Maintenance Framework for MPLS-Based Transport Networks",
RFC 6371, September 2011
10.2. Informative References [1] Vigoureux, M., Ed., Ward, D., Ed., and M. Betts, Ed.,
"Requirements for Operations, Administration, and Maintenance
(OAM) in MPLS Transport Networks", RFC 5860, May 2010.
[7] L. Fang, "Security Framework for MPLS and GMPLS Networks", RFC [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
5920, July 2010. Levels", BCP 14, RFC 2119, March 1997.
[8] S. Bryant, G. Swallow, L. Martini "Pseudowire Emulation Edge- [3] Allan, D., Ed., Swallow, G., Ed., and J. Drake, Ed., "Proactive
to-Edge (PWE3) Control Word for Use over an MPLS PSN", RFC Connectivity Verification, Continuity Check, and Remote Defect
4385, Feb 2006. Indication for the MPLS Transport Profile", RFC 6428, November
2011.
[9] Frost, D., Ed., Bryant, S., Ed., and M. Bocci, Ed., "MPLS [4] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed., "MPLS
Transport Profile Data Plane Architecture", RFC 5960, August Generic Associated Channel", RFC 5586, June 2009.
2010.
Editors' Addresses [5] Nadeau, T., Ed., and C. Pignataro, Ed., "Pseudowire Virtual
Circuit Connectivity Verification (VCCV): A Control Channel for
Pseudowires", RFC 5085, December 2007.
Sami Boutros [6] Busi, I., Ed., and D. Allan, Ed., "Operations, Administration,
Cisco Systems, Inc. and Maintenance Framework for MPLS-Based Transport Networks", RFC
Email: sboutros@cisco.com 6371, September 2011.
Siva Sivabalan 10.2. Informative References
Cisco Systems, Inc.
Email: msiva@cisco.com
Rahul Aggarwal [7] Fang, L., Ed., "Security Framework for MPLS and GMPLS Networks",
Arktan, Inc RFC 5920, July 2010.
EMail: raggarwa_1@yahoo.com
Martin Vigoureux [8] Bryant, S., Swallow, G., Martini, L., and D. McPherson,
Alcatel-Lucent. "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for Use
Email: martin.vigoureux@alcatel-lucent.com over an MPLS PSN", RFC 4385, February 2006.
Xuehui Dai [9] Frost, D., Ed., Bryant, S., Ed., and M. Bocci, Ed., "MPLS
ZTE Corporation. Transport Profile Data Plane Architecture", RFC 5960, August
Email: dai.xuehui@zte.com.cn 2010.
Contributing Authors Contributing Authors
George Swallow George Swallow
Cisco Systems, Inc. Cisco Systems, Inc.
Email: swallow@cisco.com EMail: swallow@cisco.com
David Ward David Ward
Juniper Networks. Juniper Networks.
Email: dward@juniper.net EMail: dward@juniper.net
Stewart Bryant Stewart Bryant
Cisco Systems, Inc. Cisco Systems, Inc.
Email: stbryant@cisco.com EMail: stbryant@cisco.com
Carlos Pignataro Carlos Pignataro
Cisco Systems, Inc. Cisco Systems, Inc.
Email: cpignata@cisco.com EMail: cpignata@cisco.com
Eric Osborne Eric Osborne
Cisco Systems, Inc. Cisco Systems, Inc.
Email: eosborne@cisco.com EMail: eosborne@cisco.com
Nabil Bitar Nabil Bitar
Verizon. Verizon.
Email: nabil.bitar@verizon.com EMail: nabil.bitar@verizon.com
Italo Busi Italo Busi
Alcatel-Lucent. Alcatel-Lucent.
Email: italo.busi@alcatel-lucent.com EMail: italo.busi@alcatel-lucent.com
Lieven Levrau Lieven Levrau
Alcatel-Lucent. Alcatel-Lucent.
Email: lieven.levrau@alcatel-lucent.com EMail: lieven.levrau@alcatel-lucent.com
Laurent Ciavaglia Laurent Ciavaglia
Alcatel-Lucent. Alcatel-Lucent.
Email: laurent.ciavaglia@alcatel-lucent.com EMail: laurent.ciavaglia@alcatel-lucent.com
Bo Wu Bo Wu
ZTE Corporation. ZTE Corporation.
Email: wu.bo@zte.com.cn EMail: wu.bo@zte.com.cn
Jian Yang Jian Yang
ZTE Corporation. ZTE Corporation.
Email: yang_jian@zte.com.cn EMail: yang_jian@zte.com.cn
Editors' Addresses
Sami Boutros
Cisco Systems, Inc.
EMail: sboutros@cisco.com
Siva Sivabalan
Cisco Systems, Inc.
EMail: msiva@cisco.com
Rahul Aggarwal
Arktan, Inc
EMail: raggarwa_1@yahoo.com
Martin Vigoureux
Alcatel-Lucent.
EMail: martin.vigoureux@alcatel-lucent.com
Xuehui Dai
ZTE Corporation.
EMail: dai.xuehui@zte.com.cn
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