draft-ietf-mpls-tp-identifiers-04.txt   draft-ietf-mpls-tp-identifiers-05.txt 
MPLS Working Group M. Bocci MPLS Working Group M. Bocci
Internet-Draft Alcatel-Lucent Internet-Draft Alcatel-Lucent
Intended status: Standards Track G. Swallow Intended status: Standards Track G. Swallow
Expires: September 4, 2011 Cisco Expires: December 16, 2011 Cisco
E. Gray E. Gray
Ericsson Ericsson
March 3, 2011 June 14, 2011
MPLS-TP Identifiers MPLS-TP Identifiers
draft-ietf-mpls-tp-identifiers-04 draft-ietf-mpls-tp-identifiers-05
Abstract Abstract
This document specifies identifiers for MPLS-TP objects. Included This document specifies identifiers for MPLS-TP objects. Included
are identifiers conformant to existing ITU conventions and are identifiers conformant to existing ITU conventions and
identifiers which are compatible with existing IP, MPLS, GMPLS, and identifiers which are compatible with existing IP, MPLS, GMPLS, and
Pseudowire definitions. Pseudowire definitions.
This document is a product of a joint Internet Engineering Task Force
(IETF) / International Telecommunication Union Telecommunication
Standardization Sector (ITU-T) effort to include an MPLS Transport
Profile within the IETF MPLS and Pseudowire Emulation Edge-to-Edge
(PWE3) architectures to support the capabilities and functionalities
of a packet transport network as defined by the ITU-T.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 4, 2011. This Internet-Draft will expire on December 16, 2011.
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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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4 1.2. Requirements Language . . . . . . . . . . . . . . . . . . 5
1.3. Notational Conventions in Backus-Naur Form . . . . . . . . 4 1.3. Notational Conventions . . . . . . . . . . . . . . . . . . 5
2. Named Entities . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Named Entities . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Uniquely Identifying an Operator . . . . . . . . . . . . . . . 5 3. Uniquely Identifying an Operator . . . . . . . . . . . . . . . 6
3.1. The Global ID . . . . . . . . . . . . . . . . . . . . . . 5 3.1. The Global ID . . . . . . . . . . . . . . . . . . . . . . 7
3.2. ITU Carrier Code . . . . . . . . . . . . . . . . . . . . . 6 3.2. ITU Carrier Code . . . . . . . . . . . . . . . . . . . . . 7
4. Node and Interface Identifiers . . . . . . . . . . . . . . . . 6 4. Node and Interface Identifiers . . . . . . . . . . . . . . . . 8
5. MPLS-TP Tunnel and LSP Identifiers . . . . . . . . . . . . . . 7 5. MPLS-TP Tunnel and LSP Identifiers . . . . . . . . . . . . . . 9
5.1. MPLS-TP Point to Point Tunnel Identifiers . . . . . . . . 8 5.1. MPLS-TP Point to Point Tunnel Identifiers . . . . . . . . 9
5.2. MPLS-TP LSP Identifiers . . . . . . . . . . . . . . . . . 8 5.2. MPLS-TP LSP Identifiers . . . . . . . . . . . . . . . . . 10
5.2.1. MPLS-TP Co-Routed Bidirectional LSP Identifiers . . . 8 5.2.1. MPLS-TP Co-Routed Bidirectional LSP Identifiers . . . 10
5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers . . . 9 5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers . . . 11
5.3. Mapping to GMPLS and RSVP-TE Signalling . . . . . . . . . 9 5.3. Mapping to RSVP Signaling . . . . . . . . . . . . . . . . 12
6. Pseudowire Path Identifiers . . . . . . . . . . . . . . . . . 10 6. Pseudowire Path Identifiers . . . . . . . . . . . . . . . . . 13
7. Maintenance Identifiers . . . . . . . . . . . . . . . . . . . 11 7. Maintenance Identifiers . . . . . . . . . . . . . . . . . . . 14
7.1. Maintenance Entity Group Identifiers . . . . . . . . . . . 11 7.1. Maintenance Entity Group Identifiers . . . . . . . . . . . 14
7.1.1. ICC-based MEG Identifiers . . . . . . . . . . . . . . 12 7.1.1. ICC-based MEG Identifiers . . . . . . . . . . . . . . 14
7.1.2. IP Compatible MEG_IDs . . . . . . . . . . . . . . . . 12 7.1.2. IP Compatible MEG_IDs . . . . . . . . . . . . . . . . 14
7.1.2.1. MPLS-TP LSP MEG_IDs . . . . . . . . . . . . . . . 12 7.1.2.1. MPLS-TP Section MEG_IDs . . . . . . . . . . . . . 14
7.1.2.2. Pseudowire MEG_IDs . . . . . . . . . . . . . . . . 12 7.1.2.2. MPLS-TP LSP MEG_IDs . . . . . . . . . . . . . . . 15
7.2. MEP_IDs . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.1.2.3. Pseudowire MEG_IDs . . . . . . . . . . . . . . . . 15
7.2.1. ICC-based MEP Identifiers . . . . . . . . . . . . . . 12 7.2. MEP_IDs . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.2.2. IP based MEP_IDs . . . . . . . . . . . . . . . . . . . 13 7.2.1. ICC-based MEP Identifiers . . . . . . . . . . . . . . 15
7.2.2.1. MPLS-TP LSP_MEP_ID . . . . . . . . . . . . . . . . 13 7.2.2. IP based MEP_IDs . . . . . . . . . . . . . . . . . . . 15
7.2.2.2. MEP_IDs for Pseudowires . . . . . . . . . . . . . 13 7.2.2.1. MPLS-TP LSP_MEP_ID . . . . . . . . . . . . . . . . 15
7.2.2.3. Pseudowire Segments Endpoint IDs . . . . . . . . . 13 7.2.2.2. MEP_IDs for Pseudowires . . . . . . . . . . . . . 16
7.3. MIP Identifiers . . . . . . . . . . . . . . . . . . . . . 14 7.2.2.3. Pseudowire Segments Endpoint IDs . . . . . . . . . 16
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 7.3. MIP Identifiers . . . . . . . . . . . . . . . . . . . . . 17
9. Security Considerations . . . . . . . . . . . . . . . . . . . 15 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 9. Security Considerations . . . . . . . . . . . . . . . . . . . 18
10.1. Normative References . . . . . . . . . . . . . . . . . . . 15 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.2. Informative References . . . . . . . . . . . . . . . . . . 16 10.1. Normative References . . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 10.2. Informative References . . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction 1. Introduction
This document specifies identifiers to be used in within the This document specifies identifiers to be used in the Transport
Transport Profile of Multiprotocol Label Switching (MPLS-TP). The Profile of Multiprotocol Label Switching (MPLS-TP). The MPLS-TP
MPLS-TP requirements (RFC 5654) [7] require that the elements and requirements (RFC 5654) [7] require that the elements and objects in
objects in an MPLS-TP environment are able to be configured and an MPLS-TP environment are able to be configured and managed without
managed without a control plane. In such an environment many a control plane. In such an environment many conventions for
conventions for defining identifiers are possible. This document defining identifiers are possible. This document defines identifiers
defines identifiers for MPLS-TP management and OAM functions suitable for MPLS-TP management and OAM functions suitable to ITU conventions
to ITU conventions and to IP/MPLS conventions. Applicability of the and to IP/MPLS conventions. Applicability of the different
different identifier schemas to different applications is outside the identifier schemas to different applications is outside the scope of
scope of this document. this document.
This document is a product of a joint Internet Engineering Task Force
(IETF) / International Telecommunication Union Telecommunication
Standardization Sector (ITU-T) effort to include an MPLS Transport
Profile within the IETF MPLS and Pseudowire Emulation Edge-to-Edge
(PWE3) architectures to support the capabilities and functionalities
of a packet transport network as defined by the ITU-T.
1.1. Terminology 1.1. Terminology
AII: Attachment Interface Identifier AII: Attachment Interface Identifier
ASN: Autonomous System Number ASN: Autonomous System Number
EGP: Exterior Gateway Protocol
FEC: Forwarding Equivalence Class FEC: Forwarding Equivalence Class
GMPLS: Generalized Multi-Protocol Label Switching GMPLS: Generalized Multi-Protocol Label Switching
ICC: ITU Carrier Code ICC: ITU Carrier Code
IGP: Interior Gateway Protocol
LSP: Label Switched Path LSP: Label Switched Path
LSR: Label Switching Router LSR: Label Switching Router
ME: Maintenance Entity ME: Maintenance Entity
MEG: Maintenance Entity Group MEG: Maintenance Entity Group
MEP: Maintenance Entity Group End Point MEP: Maintenance Entity Group End Point
skipping to change at page 4, line 18 skipping to change at page 5, line 30
S-PE: Switching Provider Edge S-PE: Switching Provider Edge
T-PE: Terminating Provider Edge T-PE: Terminating Provider Edge
1.2. Requirements Language 1.2. Requirements Language
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 [1]. document are to be interpreted as described in RFC 2119 [1].
1.3. Notational Conventions in Backus-Naur Form 1.3. Notational Conventions
All multiple-word atomic identifiers use underscores (_) between the All multiple-word atomic identifiers use underscores (_) between the
words to join the words. Many of the identifiers are composed of a words to join the words. Many of the identifiers are composed of a
concatenation of other identifiers. These are expressed using set of other identifiers. These are expressed by listing the latter
Backus-Naur Form (using double-colon - "::" - notation). identifiers joined with double-colon, "::", notation.
Where the same identifier type is used multiple times in a Where the same identifier type is used multiple times in a
concatenation, they are qualified by a prefix joined to the concatenation, they are qualified by a prefix joined to the
identifier by a dash (-). For example East-Node_ID is the Node_ID of identifier by a dash (-). For example A1-Node_ID is the Node_ID of a
a node referred to as East. node referred to as A1.
The notation does define a preferred ordering of the fields.
Specifically the designation A1 is used to indicate the lower sort
order of a field or set of fields and Z9 is used to indicated the
higher sort order of the same. The sort is either alphanumeric or
numeric depending on the field's definition. Where the sort applies
to a group of fields, those fields are grouped with {...}.
Note, however, that the uniqueness of an identifier does not depend
on the ordering, but rather, upon the uniqueness and scoping of the
fields that compose the identifier. Further the preferred ordering
is not intended to constrain protocol designs by dictating a
particular field sequence or even what fields appear in which
objects. For example see Section 5.3.
2. Named Entities 2. Named Entities
In order to configure, operate and manage a transport network based In order to configure, operate and manage a transport network based
on the MPLS Transport Profile, a number of entities require on the MPLS Transport Profile, a number of entities require
identification. Identifiers for the follow entities are defined in identification. Identifiers for the following entities are defined
this document: in this document:
o Operator * Operator
* Global_ID + Global_ID
* ICC + ICC
o LSR * LSR
o LSP * LSP
o PW * PW
o Interface * Interface
o MEG
o MEP * MEG
o MIP * MEP
o Tunnel * MIP
* Tunnel
Note that we have borrowed the term tunnel from RSVP-TE (RFC 3209) Note that we have borrowed the term tunnel from RSVP-TE (RFC 3209)
[2] where it is used to describe an entity that provides a logical [2] where it is used to describe an entity that provides a logical
association between a source and destination LSR. The tunnel in turn association between a source and destination LSR. The tunnel in turn
is instantiated by one or more LSPs, where the additional LSPs are is instantiated by one or more LSPs, where the additional LSPs are
used for protection or re-grooming of the tunnel. used for protection or re-grooming of the tunnel.
3. Uniquely Identifying an Operator 3. Uniquely Identifying an Operator
An operator is uniquely identified by an Operator Identifier An operator is uniquely identified by an identifier which may take
(Opr_ID). Two formats are defined, one that is compatible with IP one of two formats. One format is compatible with IP operational
operational practice called a Global_ID and or one compatible with practice, and is called a Global_ID. The other format is compatible
ITU practice, the ICC. An The Opr_ID MAY use either the Global_ID or with ITU practice and is called ICC. An operator MAY use either the
ICC format. Global_ID or ICC format.
3.1. The Global ID 3.1. The Global ID
RFC 5003 [3] defines a globally unique Attachment Interface RFC 5003 [3] defines a globally unique Attachment Interface
Identifier (AII). That AII is composed of three parts, a Global_ID Identifier (AII). That AII is composed of three parts, a Global_ID
which uniquely identifies a operator, a prefix, and finally and which uniquely identifies an operator, a prefix, and finally, an
attachment circuit identifier. We have chosen to use that Global ID attachment circuit identifier. We have chosen to use that Global ID
for MPLS-TP. Quoting from RFC 5003, section 3.2, "The global ID can for MPLS-TP. Quoting from RFC 5003, section 3.2, "The global ID can
contain the 2-octet or 4-octet value of the operator's Autonomous contain the 2-octet or 4-octet value of the operator's Autonomous
System Number (ASN). It is expected that the global ID will be System Number (ASN). It is expected that the global ID will be
derived from the globally unique ASN of the autonomous system hosting derived from the globally unique ASN of the autonomous system hosting
the PEs containing the actual AIIs. The presence of a global ID the PEs containing the actual AIIs. The presence of a global ID
based on the operator's ASN ensures that the AII will be globally based on the operator's ASN ensures that the AII will be globally
unique." unique."
When the Global_ID is derived from a 2-octet AS number, the two high- A Global_ID must be derived from a 4-octet AS number assigned to the
order octets of this 4-octet identifier MUST be set to zero. Further operator. Note that 2-octet AS numbers have been incorporated in the
ASN 0 is reserved. A Global_ID of zero means that no Global_ID is 4-octet by placing the 2-octet AS number, in the low-order octets and
present. Note that a Global_ID of zero is limited to entities setting the two high-order octets to zero.
contained within a single operator and MUST NOT be used across an
NNI. A non-zero Global_ID MUST be derived from an ASN owned by the
operator.
Note that this Global_ID is used solely to provide a globally unique ASN 0 is reserved and cannot be assigned. A Global_ID of zero means
context for other MPLS-TP identifiers. It has nothing to do with the that no Global_ID is specified. Note that a Global_ID of zero is
use of the ASN in protocols such as BGP. limited to entities contained within a single operator and MUST NOT
be used across an NNI.
The Global_ID is used solely to provide a globally unique context for
other MPLS-TP identifiers. While the AS Number used in the Global_ID
MUST be one which the operator is entitles to use, the use of the
Global_ID is not related to the use of the ASN in protocols such as
BGP.
3.2. ITU Carrier Code 3.2. ITU Carrier Code
M.1400 defines the ITU Carrier Code (ICC) assigned to a network M.1400 defines the ITU Carrier Code (ICC) assigned to a network
operator/service provider and maintained by the ITU-T operator/service provider and maintained by the ITU-T
Telecommunication Standardization Bureau (TSB): www.itu.int/ITU-T/ Telecommunication Standardization Bureau (TSB): www.itu.int/ITU-T/
inr/icc/index.html. inr/icc/index.html.
ICCs can be assigned both to ITU-T and non-ITU-T members and the ICCs can be assigned both to ITU-T and non-ITU-T members and the
referenced local ICC website may contain ICCs of operators of both referenced local ICC website may contain ICCs of operators of both
kinds. kinds.
The ICC is a string of one to six characters, each character being The ICC is a string of one to six characters, each character being
either alphabetic (i.e. A-Z) or numeric (i.e. 0-9) characters. either alphabetic (i.e. A-Z) or numeric (i.e. 0-9) characters.
Alphabetic characters in the ICC SHOULD be represented with upper Alphabetic characters in the ICC SHOULD be represented with upper
case letters. case letters.
4. Node and Interface Identifiers 4. Node and Interface Identifiers
An LSR requires identification of the node itself and of its An LSR requires identification of the node itself and of its
interfaces. An interface is the attachment point to a server layer interfaces. An interface is the attachment point to a server
MPLS-TP section or MPLS-TP tunnel. (sub-)layer, e.g., MPLS-TP section or MPLS-TP tunnel.
We call the identifier associated with a node a Node Identifier We call the identifier associated with a node a Node Identifier
(Node_ID). The Node_ID is a unique 32-bit value assigned by the (Node_ID). The Node_ID is a unique 32-bit value assigned by the
operator within the scope of the Global_ID. The structure of the operator within the scope of a Global_ID or ICC. The structure of
Node_ID is operator specific and is outside the scope of this the Node_ID is operator specific and is outside the scope of this
document. However, the value zero is reserved and MUST NOT be used. document. However, the value zero is reserved and MUST NOT be used.
Where IPv4 addresses are used, it may be convenient to use the Node's Where IPv4 addresses are used, it may be convenient to use the Node's
IPv4 loopback address as the Node_ID, however the Node_ID does not IPv4 loopback address as the Node_ID, however the Node_ID does not
need to have any association with the IPv4 address space used in the need to have any association with the IPv4 address space used in the
operator's IGP or BGP. Where IPv6 addresses are used exclusively, a operator's IGP or EGP. Where IPv6 addresses are used exclusively, a
32-bit value unique within the scope of the Global_ID is assigned. 32-bit value unique within the scope of a Global_ID or ICC is
assigned.
A LSR can support multiple layers (e.g. hierarchical LSPs) and the An LSR can support multiple layers (e.g. hierarchical LSPs) and the
Node_ID belongs to the multiple layer context i.e. it is applicable Node_ID belongs to the multiple layer context i.e. it is applicable
to all LSPs or PWs that originate on, have a midpoint on, or to all LSPs or PWs that originate on, have a intermediate point on,
terminate on the node. or terminate on the node.
In situations where a Node_ID needs to be globally unique, this is In situations where a Node_ID needs to be globally unique, this is
accomplished by prefixing the identifier with the operator's Opr_ID. accomplished by prefixing the identifier with the operator's
The particular combination of Global_ID::Node_ID we call a Global Global_ID or ICC.
Node ID or Global_Node_ID.
Within the context of a particular node, we call the identifier Within the context of a particular node, we call the identifier
associated with an interface an Interface Number or IF_Num. The associated with an interface an Interface Number (IF_Num). The
IF_Num is a 32-bit unsigned integer assigned by the operator and MUST IF_Num is a 32-bit unsigned integer assigned by the operator and MUST
be unique within the scope of a Node_ID. The IF_Num value 0 has be unique within the scope of a Node_ID. The IF_Num value 0 has
special meaning (see section , MIP Identifiers) (Section 7.3) and special meaning (see Section 7.3, MIP Identifiers) and MUST NOT be
MUST NOT be used to identify an MPLS-TP interface. used to identify an MPLS-TP interface.
An Interface Identifier or IF_ID identifies an interface uniquely An Interface Identifier (IF_ID) identifies an interface uniquely
within the context of an Opr_ID. It is formed by concatenating the within the context of a Global_ID or ICC. It is formed by
Node_ID with the IF_Num. That is an IF_ID is a 64-bit identifier concatenating the Node_ID with the IF_Num. That is an IF_ID is a 64-
formed as Node_ID::IF_Num. bit identifier formed as Node_ID::IF_Num.
This convention was chosen to allow compatibility with GMPLS. GMPLS This convention was chosen to allow compatibility with GMPLS. GMPLS
signaling [4] requires interface identification. GMPLS allows three signaling [4] requires interface identification. GMPLS allows three
formats for the Interface_ID. The third format consists of an IPv4 formats for the Interface_ID. The third format consists of an IPv4
Address plus a 32-bit unsigned integer for the specific interface. Address plus a 32-bit unsigned integer for the specific interface.
The format defined for MPLS-TP is consistent with this format, but The format defined for MPLS-TP is consistent with this format, but
uses the Node_ID instead of an IPv4 Address. uses the Node_ID instead of an IPv4 Address.
If an IF_ID needs to be globally unique, this is accomplished by If an IF_ID needs to be globally unique, this is accomplished by
prefixing the identifier with the operator's Opr_ID. prefixing the identifier with the operator's Global_ID or ICC.
The attachment point to an MPLS-TP Tunnel (see section Section 5.1 The attachment point to an MPLS-TP Tunnel (see Section 5.1) also
also needs an interface identifier. Note that MPLS-TP supports needs an interface identifier. Note that MPLS-TP supports
hierarchical tunnels. The attachment point to a MPLS-TP Tunnel at hierarchical tunnels. The attachment point to a MPLS-TP Tunnel at
any sub layer requires a unique IF_ID. any (sub-)layer requires a node-unique IF_Num.
5. MPLS-TP Tunnel and LSP Identifiers 5. MPLS-TP Tunnel and LSP Identifiers
In MPLS the actual transport of packets is provided by label switched In MPLS the actual transport of packets is provided by label switched
paths (LSPs). A transport service may be composed of multiple LSPs. paths (LSPs). A transport service may be composed of multiple LSPs.
Further the LSPs providing a service may change over time due to Further the LSPs providing a service may change over time due to
protection and restoration events. In order to clearly identify the protection and restoration events. In order to clearly identify the
service we use the term "MPLS-TP Tunnel" or simply "tunnel" for a service we use the term "MPLS-TP Tunnel" or simply "tunnel" for a
service provided by (for example) a working LSP and protected by a service provided by (for example) a working LSP and protected by a
protection LSP. The Tunnel_ID identifies the transport service and protection LSP. The Tunnel_ID identifies the transport service and
provides a stable binding to the client in the face of changes in the provides a stable binding to the client in the face of changes in the
the data plane LSPs used to provide the service due to protection and the data plane LSPs used to provide the service due to protection or
restoration events. This section defines an MPLS-TP Tunnel_ID to restoration events. This section defines an MPLS-TP Tunnel_ID to
uniquely identify a tunnel and MPLS-TP LSP_IDs within the context of uniquely identify a tunnel and MPLS-TP LSP_IDs within the context of
that tunnel. that tunnel.
For the case where multiple LSPs (for example) are used to support a For the case where multiple LSPs (for example) are used to support a
single service with a common set of end-points, using this identifier single service with a common set of end-points, using this identifier
allows for a trivial mapping between the server and client layers to allows for a trivial mapping between the server and client layers,
a common service identifier which may be either defined by, or used providing a common service identifier which may be either defined by,
by, the client. or used by, the client.
Note that this usage is not intended to constrain protection schemes, Note that this usage is not intended to constrain protection schemes,
and may be used to identify any service (protected or un-protected) and may be used to identify any service (protected or unprotected)
that may appear to the client as a single service attachment point. that may appear to the client as a single service attachment point.
Keeping the Tunnel_ID consistent across working and protection LSPs
Keeping the tunnel number consistent across working and protection is a useful construct currently employed within GMPLS. The Tunnel_ID
LSPs is a useful construct currently employed within GMPLS. However for a protection LSP MAY differ from that used by its corresponding
there is no requirement that a protection LSP use the same tunnel working LSP.
number as the working LSP.
5.1. MPLS-TP Point to Point Tunnel Identifiers 5.1. MPLS-TP Point to Point Tunnel Identifiers
At each endpoint a tunnel is uniquely identified by the endpoint's At each endpoint a tunnel is uniquely identified by the endpoint's
Node_ID and a locally assigned tunnel number. Specifically a Node_ID and a locally assigned tunnel number. Specifically a
Tunnel_Num is a 16-bit unsigned integer unique within the context of Tunnel_Num is a 16-bit unsigned integer unique within the context of
the Node_ID. The motivation for each endpoint having its own tunnel the Node_ID. The motivation for each endpoint having its own tunnel
number is to allow a compact form for the MEP-ID. See section number is to allow a compact form for the MEP-ID. See
Section 7.1.2.1. Section 7.2.2.1.
Having two tunnel numbers also serves to simplify other signaling Having two tunnel numbers also serves to simplify other signaling
(e.g., setup of associated bi-directional tunnels as described in (e.g., setup of associated bidirectional tunnels as described in
section Section 5.3.) Section 5.3).
The concatenation of the two endpoint identifiers serves as the full The concatenation of the two endpoint identifiers serves as the full
identifier. In a configured environment the endpoints are often identifier. Using the A1 / Z9 convention the format of a Tunnel_ID
called East and West. Using this convention the format of the format is:
of a Tunnel_ID is:
East-Node_ID::East-Tunnel_Num::West-Node_ID::West-Tunnel_Num A1-{Node_ID::Tunnel_Num}::Z9-{Node_ID::Tunnel_Num}
Where the Tunnel_ID needs to be globally unique, this is accomplished Where the Tunnel_ID needs to be globally unique, this is accomplished
by using globally unique Node_IDs as defined above. Thus a globally by using globally unique Node_IDs as defined above. Thus a globally
unique Tunnel_ID becomes: unique Tunnel_ID becomes:
East-Global_Node_ID::East-Tunnel_Num::West-Global_Node_ID:: A1-{Global_ID::Node_ID::Tunnel_Num}::Z9-{Global_Id::Node_ID::
West-Tunnel_Num Tunnel_Num}
The corresponding ICC-based version of this identifier would be:
A1-{ICC::Node_ID::Tunnel_Num}::Z9-{ICC::Node_ID::Tunnel_Num}
When an MPLS-TP Tunnel is configured, it MUST be assigned a unique When an MPLS-TP Tunnel is configured, it MUST be assigned a unique
IF_ID at both the source and destination endpoints. As usual, the IF_ID at each endpoint. As usual, the IF_ID is composed of the local
IF_ID is composed of the local NODE_ID concatenated with a 32-bit Node_ID concatenated with a 32-bit IF_Num.
IF_Num.
5.2. MPLS-TP LSP Identifiers 5.2. MPLS-TP LSP Identifiers
5.2.1. MPLS-TP Co-Routed Bidirectional LSP Identifiers 5.2.1. MPLS-TP Co-Routed Bidirectional LSP Identifiers
For a co-routed bidirectional LSP can be uniquely identified by a A co-routed bidirectional LSP can be uniquely identified by a single
single LSP number within the scope of an MPLS-TP Tunnel_ID. LSP number within the scope of an MPLS-TP Tunnel_ID. Specifically an
Specifically an LSP_Num is a 16-bit unsigned integer unique within LSP_Num is a 16-bit unsigned integer unique within the Tunnel_ID.
the Tunnel_ID. Thus the format of a LSP_ID is: Thus the format of an MPLS-TP co-routed bidirectional LSP_ID is:
East-Node_ID::East-Tunnel_Num::West-Node_ID::West- A1-{Node_ID::Tunnel_Num}::Z9-{Node_ID::Tunnel_Num}::LSP_Num
Tunnel_Num::LSP_Num
Note that the uniqueness of identifiers does not depend on the A1 /
Z9 sort ordering. Thus the identifier,
Z9-{Node_ID::Tunnel_Num}::A1-{Node_ID::Tunnel_Num}::LSP_Num
is synonymous with the one above.
At the dataplane level, a co-routed bidirectional LSP is composed of
two unidirectional LSPs traversing the same links in opposite
directions. Since a co-routed bidirectional LSP is provisioned or
signaled as a single entity, a single LSP_Num is used for both
unidirectional LSPs. The unidirectional LSPs can be referenced by
the identifiers:
Z9-Node_ID::Z9-Tunnel_Num::LSP_Num::A1-Node_ID and
A1-Node_ID::A1-Tunnel_Num::LSP_Num::Z9-Node_ID respectively.
Where the LSP_ID needs to be globally unique, this is accomplished by Where the LSP_ID needs to be globally unique, this is accomplished by
using globally unique Node_IDs as defined above. Thus a globally using globally unique Node_IDs as defined above. Thus a globally
unique LSP_ID becomes: unique LSP_ID becomes:
East-Global_Node_ID::East-Tunnel_Num::West-Global_Node_ID:: A1-{Global_ID::Node_ID::Tunnel_Num}::Z9-{Global_Id::
West-Tunnel_Num::LSP_Num Node_ID::Tunnel_Num}::LSP_Num
The corresponding ICC-based version of this identifier would be: The corresponding ICC-based version of this identifier would be:
East-ICC::East-Node_ID::East-Tunnel_Num::West-ICC::West-Node_ID::
West-Tunnel_Num::LSP_Num A1-{ICC::Node_ID::Tunnel_Num}::Z9-{ICC::Node_ID::Tunnel_Num}::
LSP_Num
5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers 5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers
For an associated bidirectional LSP each of the unidirectional LSPs For an associated bidirectional LSP each of the unidirectional LSPs
from East to West and West to East require LSP IDs. The each LSP can from A1 to Z9 and Z9 to A1 require LSP_Nums. Each LSP is uniquely
be uniquely identified by a single LSP number within the scope of the identified by a single LSP number within the scope of the ingress's
senders Tunnel_Num. Specifically an LSP_Num is a 16-bit unsigned Tunnel_Num. Specifically an LSP_Num is a 16-bit unsigned integer
integer unique within the Tunnel_Num. Thus the format of a LSP_ID is: unique within the Tunnel_Num. Thus the format of an MPLS-TP
associated bidirectional LSP_ID is:
East-Node_ID::East-Tunnel_Num::East-LSP_Num:: A1-{Node_ID::Tunnel_Num::LSP_Num}::
Z9-{Node_ID::Tunnel_Num::LSP_Num}
West-Node_ID::West-Tunnel_Num::West-LSP_Num At the dataplane level, an associated bidirectional LSP is composed
of two unidirectional LSPs between two nodes in opposite directions.
The unidirectional LSPs may be referenced by the identifiers:
A1-Node_ID::A1-Tunnel_Num::A1-LSP_Num::Z9-Node_ID and
Z9-Node_ID::Z9-Tunnel_Num::Z9-LSP_Num::A1-Node_ID respectively.
Where the LSP_ID needs to be globally unique, this is accomplished by Where the LSP_ID needs to be globally unique, this is accomplished by
using globally unique Node_IDs as defined above. Thus a globally using globally unique Node_IDs as defined above. Thus a globally
unique LSP_ID becomes: unique LSP_ID becomes:
East-Global_Node_ID::East-Tunnel_Num::East-LSP_Num:: A1-{Global_ID::Node_ID::Tunnel_Num::LSP_Num}::
West-Global_Node_ID::West-Tunnel_Num::West-LSP_Num Z9-{Global_Id::Node_ID::Tunnel_Num::LSP_Num}
The corresponding ICC-based version of this identifier would be: The corresponding ICC-based version of this identifier would be:
East-ICC::East-Node_ID::East-Tunnel_Num::East-LSP_Num:: A1-{ICC::Node_ID::Tunnel_Num::LSP_Num}::
West-ICC::West-Node_ID::West-Tunnel_Num::West-LSP_Num Z9-{ICC::Node_ID::Tunnel_Num::LSP_Num}
5.3. Mapping to GMPLS and RSVP-TE Signalling 5.3. Mapping to RSVP Signaling
This section defines the mapping from an MPLS-TP LSP_ID to GMPLS. At This section is informative and exists to help understand the
this time, GMPLS has yet to be extended to accommodate Global_IDs. structure of the LSP IDs.
Thus a mapping is only made for the network unique form of the
LSP_ID.
GMPLS signaling [5] uses a 5-tuple to uniquely identify an LSP within Both GMPLS and RSVP-TE use RSVP signaling. This section defines the
mapping from an MPLS-TP LSP_ID to RSVP. At this time, RSVP has yet
to be extended to accommodate Global_IDs. Thus a mapping is only
made for the network unique form of the LSP_ID.
RSVP signaling [5] uses a 5-tuple to uniquely identify an LSP within
a operator's network. This tuple is composed of a Tunnel Endpoint a operator's network. This tuple is composed of a Tunnel Endpoint
Address, Tunnel_ID, Extended Tunnel ID, and Tunnel Sender Address and Address, Tunnel_ID, Extended Tunnel ID, and Tunnel Sender Address and
(GMPLS) LSP_ID. (RSVP) LSP_ID.
In situations where a mapping to the GMPLS 5-tuple is required, the For a co-routed bidirectional LSP signaled from A1 to Z9, the mapping
following mapping is used. to the GMPLS 5-tuple is as follows:
o Tunnel Endpoint Address = West-Node_ID * Tunnel Endpoint Address = Z9-Node_ID
o Tunnel_ID = East-Tunnel_Num * Tunnel_ID = A1-Tunnel_Num
o Extended Tunnel_ID = East-Node_ID * Extended Tunnel_ID = A1-Node_ID
o Tunnel Sender Address = East-Node_ID * Tunnel Sender Address = A1-Node_ID
o LSP_ID = East-LSP_Num * (RSVP) LSP_ID = LSP_Num
An associated bi-directional LSP between two nodes East and West An associated bidirectional LSP between two nodes A1 and Z9 consists
consists of two uni-directional LSPs, one from East to West and one of two unidirectional LSPs, one from A1 to Z9 and one from Z9 to A1.
from West to East. RSVP-TE is capable of signaling such LSPs.
In situations where a mapping to the RSVP 5-tuples is required, the In situations where a mapping to the RSVP 5-tuples is required, the
following mappings are used. For the East to West LSP the mapping following mappings are used. For the A1 to Z9 LSP the mapping would
would be: be:
o Tunnel Endpoint Address = West-Node_ID * Tunnel Endpoint Address = Z9-Node_ID
o Tunnel_ID = East-Tunnel_Num * Tunnel_ID = A1-Tunnel_Num
o Extended Tunnel_ID = East-Node_ID * Extended Tunnel_ID = A1-Node_ID
o Tunnel Sender Address = East-Node_ID * Tunnel Sender Address = A1-Node_ID
o LSP_ID = East-LSP_Num * (RSVP) LSP_ID = A1-LSP_Num
Likewise, the East to West LSP the mapping would be: Likewise, the Z9 to A1 LSP, the mapping would be:
o Tunnel Endpoint Address = East-Node_ID * Tunnel Endpoint Address = A1-Node_ID
o Tunnel_ID = West-Tunnel_Num * Tunnel_ID = Z9-Tunnel_Num
o Extended Tunnel_ID = West-Node_ID * Extended Tunnel_ID = Z9-Node_ID
o Tunnel Sender Address = West-Node_ID * Tunnel Sender Address = Z9-Node_ID
o LSP_ID = West-LSP_Num * (RSVP) LSP_ID = Z9-LSP_Num
6. Pseudowire Path Identifiers 6. Pseudowire Path Identifiers
Pseudowire signaling (RFC 4447 [6]) defines two FECs used to signal Pseudowire signaling (RFC 4447 [6]) defines two FECs used to signal
pseudowires. Of these, FEC Type 129 along with AII Type 2 as defined pseudowires. Of these, FEC Type 129 along with AII Type 2 as defined
in RFC 5003 [3] fits the identification requirements of MPLS-TP. in RFC 5003 [3] fits the identification requirements of MPLS-TP.
In an MPLS-TP environment, a PW is identified by a set of identifiers In an MPLS-TP environment, a PW is identified by a set of identifiers
which can be mapped directly to the elements required by FEC 129 and which can be mapped directly to the elements required by FEC 129 and
AII Type 2. To distinguish this identifier from other Pseudowire AII Type 2. To distinguish this identifier from other Pseudowire
Identifiers, we call this a Pseudowire Path Identifier or PW_Path_Id. Identifiers, we call this a Pseudowire Path Identifier (PW_Path_Id).
The AII Type 2 is composed of three fields. These are the Global_ID, The AII Type 2 is composed of three fields. These are the Global_ID,
the Prefix, and the AC_ID. The Global_ID used in this document is the Prefix, and the AC_ID. The Global_ID used in this document is
identical to the Global_ID defined in RFC 5003. The Node_ID is used identical to the Global_ID defined in RFC 5003. The Node_ID is used
as the Prefix. The AC_ID is as defined in RFC 5003. as the Prefix. The AC_ID is as defined in RFC 5003.
To complete the FEC 129, all that is required is a Attachment Group To complete the FEC 129, all that is required is a Attachment Group
Identifier (AGI). That field is exactly as specified in RFC 4447. Identifier (AGI). That field is exactly as specified in RFC 4447.
FEC 129 has a notion of Source AII (SAII) and Target AII (TAII). FEC 129 has a notion of Source AII (SAII) and Target AII (TAII).
These terms are used relative to the direction of the signaling. In These terms are used relative to the direction of the signaling. In
a purely configured environment when referring to the entire PW, this a purely configured environment when referring to the entire PW, this
distinction is not critical. That is a FEC 129 of AGIa::AIIb::AIIc distinction is not critical. That is a FEC 129 of AGIa::AIIb::AIIc
is equivalent to AGIa::AIIc::AIIb. We note that in a signaled is equivalent to AGIa::AIIc::AIIb. We note that in a signaled
environment, the required convention in RFC 4447 is that at a environment, the required convention in RFC 4447 is that at a
particular endpoint, the AII associated with that endpoint comes particular endpoint, the AII associated with that endpoint comes
first. The complete PW_Path_Id is: first. The complete PW_Path_Id is:
AGI::East-Global_Node_ID::East-AC_ID::West-Global_Node_ID:: AGI::A1-{Global_ID::Node_ID::AC_ID}::
West-AC_ID. Z9-{Global_Id::Node_ID::AC_ID}.
The corresponding ICC-based version for this identifier would be: The corresponding ICC-based version for this identifier would be:
AGI::East-ICC::East-Node_ID::East-AC_ID::West-ICC::West-Node_ID:: AGI::A1-{ICC::Node_ID::AC_ID}::Z9-{ICC::Node_ID::AC_ID}
West-AC_ID
7. Maintenance Identifiers 7. Maintenance Identifiers
In MPLS-TP a Maintenance Entity Group (MEG) represents an Entity that In MPLS-TP a Maintenance Entity Group (MEG) represents an Entity that
requires management and defines a relationship between a set of requires management and defines a relationship between a set of
maintenance points. A maintenance point is either Maintenance Entity maintenance points. A maintenance point is either a Maintenance
Group End-point (MEP) or a Maintenance Entity Group Intermediate Entity Group End-point (MEP) or a Maintenance Entity Group
Point (MIP). Maintenance points are uniquely associated with a MEG. Intermediate Point (MIP). Maintenance points are uniquely associated
Within the context of a MEG, MEPs and MIPs must be uniquely with a MEG. Within the context of a MEG, MEPs and MIPs must be
identified. This section defines a means of uniquely identifying uniquely identified. This section defines a means of uniquely
Maintenance Entity Groups, Maintenance Entities and uniquely defining identifying Maintenance Entity Groups, Maintenance Entities and
MEPs and MIPs within the context of a Maintenance Entity Group. uniquely defining MEPs and MIPs within the context of a Maintenance
Entity Group.
7.1. Maintenance Entity Group Identifiers 7.1. Maintenance Entity Group Identifiers
Maintenance Entity Group Identifiers (MEG_IDs) are required for Maintenance Entity Group Identifiers (MEG_IDs) are required for
MPLS-TP LSPs and Pseudowires. Two classes of MEG_IDs are defined, MPLS-TP sections, LSPs and Pseudowires. Two classes of MEG_IDs are
one that follows the IP compatible identifier defined above as well defined, one that follows the IP compatible identifier defined above
as the ICC-format. as well as the ICC-format.
7.1.1. ICC-based MEG Identifiers 7.1.1. ICC-based MEG Identifiers
MEG_ID for MPLS-TP LSPs and Pseudowires MAY use the globally unique MEG_ID for MPLS-TP LSPs and Pseudowires MAY use the globally unique
ICC-based format. ICC-based format.
In this case, the MEG_ID is a string of up to thirteen characters, In this case, the MEG_ID is a string of up to thirteen characters,
each character being either alphabetic (i.e. A-Z) or numeric (i.e. each character being either alphabetic (i.e. A-Z) or numeric (i.e.
0-9) characters. It consists of two subfields: the ICC (as defined 0-9) characters. It consists of two subfields: the ICC (as defined
in section 3) followed by a unique MEG code (UMC). The UMC MUST be in section 3) followed by a unique MEG code (UMC). The UMC MUST be
unique within the organization identified by the ICC. unique within the organization identified by the ICC.
The ICC MEG_ID may be applied equally to a single MPLS-TP LSP or The ICC MEG_ID may be applied equally to a single MPLS-TP LSP or
Pseudowires. Note that when encoded in a protocol such as in a TLV, Pseudowires. Note that when encoded in a protocol such as in a TLV,
a different type needs to be defined for LSP and PWs as the OAM a different type needs to be defined for LSP and PWs as the OAM
capabilities may be different. capabilities may be different.
7.1.2. IP Compatible MEG_IDs 7.1.2. IP Compatible MEG_IDs
7.1.2.1. MPLS-TP LSP MEG_IDs 7.1.2.1. MPLS-TP Section MEG_IDs
IP compatible MEG_IDs for MPLS-TP sections are formed by
concatenating the two IF_IDs of the corresponding section. For
example:
A1-IF_ID::Z9-IF_ID
Where the LSP_ID needs to be globally unique, this is accomplished by
using globally unique Node_IDs as defined above. Thus a globally
unique Section MEG_ID becomes:
A1-{Global_ID::IF_ID}::Z9-{Global_Id::IF_ID}
7.1.2.2. MPLS-TP LSP MEG_IDs
Since a MEG pertains to a single MPLS-TP LSP, IP compatible MEG_IDs Since a MEG pertains to a single MPLS-TP LSP, IP compatible MEG_IDs
for MPLS-TP LSPs are simply the corresponding LSP_IDs. We note that for MPLS-TP LSPs are simply the corresponding LSP_IDs. We note that
while the two identifiers are syntactically identical, they have while the two identifiers are syntactically identical, they have
different semantics. This semantic difference needs to be made different semantics. This semantic difference needs to be made
clear. For instance if both a MPLS-TP LSP_ID and MPLS-TP LSP MEG_IDs clear. For instance if both a MPLS-TP LSP_ID and MPLS-TP LSP MEG_IDs
are to be encoded in TLVs different types need to be assigned for are to be encoded in TLVs, different types need to be assigned for
these two identifiers. these two identifiers.
7.1.2.2. Pseudowire MEG_IDs 7.1.2.3. Pseudowire MEG_IDs
For Pseudowires a MEG pertains to a single PW. The IP compatible For Pseudowires a MEG pertains to a single PW. The IP compatible
MEG_ID for a PW is simply the corresponding PW_Path_ID. We note that MEG_ID for a PW is simply the corresponding PW_Path_ID. We note that
while the two identifiers are syntactically identical, they have while the two identifiers are syntactically identical, they have
different semantics. This semantic difference needs to be made different semantics. This semantic difference needs to be made
clear. For instance if both a PW_Path_ID and a PW_MEG_ID is to be clear. For instance if both a PW_Path_ID and a PW_MEG_ID are to be
encoded in TLVs different types need to be assigned for these two encoded in TLVs, different types need to be assigned for these two
identifiers. identifiers.
7.2. MEP_IDs 7.2. MEP_IDs
7.2.1. ICC-based MEP Identifiers 7.2.1. ICC-based MEP Identifiers
ICC-based MEP_IDs for MPLS-TP LSPs and Pseudowires are formed by ICC-based MEP_IDs for MPLS-TP LSPs and Pseudowires are formed by
appending a unique number to the MEG_ID defined in section appending a unique number to the MEG_ID defined in Section 7.1.1
Section 7.1.1 above. Within the context of a particular MEG, we call above. Within the context of a particular MEG, we call the
the identifier associated with a MEP the MEP Index (MEP_Index). The identifier associated with a MEP the MEP Index (MEP_Index). The
MEP_Index is administratively assigned. It is encoded as a 16-bit MEP_Index is administratively assigned. It is encoded as a 16-bit
unsigned integer and MUST be unique within the MEG. An ICC-based unsigned integer and MUST be unique within the MEG. An ICC-based
MEP_ID is: MEP_ID is:
MEG_ID::MEP_Index MEG_ID::MEP_Index
An ICC-based MEP ID is globally unique by construction given the ICC- An ICC-based MEP ID is globally unique by construction given the ICC-
based MEG_ID global uniqueness. based MEG_ID global uniqueness.
7.2.2. IP based MEP_IDs 7.2.2. IP based MEP_IDs
skipping to change at page 13, line 23 skipping to change at page 16, line 9
7.2.2.1. MPLS-TP LSP_MEP_ID 7.2.2.1. MPLS-TP LSP_MEP_ID
In order to automatically generate MEP_IDs for MPLS-TP LSPs, we use In order to automatically generate MEP_IDs for MPLS-TP LSPs, we use
the elements of identification that are unique to an endpoint. This the elements of identification that are unique to an endpoint. This
ensures that MEP_IDs are unique for all LSPs within a operator. When ensures that MEP_IDs are unique for all LSPs within a operator. When
Tunnels or LSPs cross operator boundaries, these are made unique by Tunnels or LSPs cross operator boundaries, these are made unique by
pre-pending them with the operator's Global_ID. pre-pending them with the operator's Global_ID.
The MPLS-TP LSP_MEP_ID is The MPLS-TP LSP_MEP_ID is
Node_ID::Tunnel_Num::LSP_Num, Node_ID::Tunnel_Num::LSP_Num
where the Node_ID is the node in which the MEP is located and where the Node_ID is the node in which the MEP is located and
Tunnel_Num is the tunnel number unique to that node. In the case of Tunnel_Num is the tunnel number unique to that node. In the case of
Associated Bi-directional LSPs, the LSP_Num unique to where the MEP co-routed bidirectional LSPs, the single LSP_Num is used at both
resides. ends. In the case of associated bidirectional LSPs, the LSP_Num is
the one unique to where the MEP resides.
In situations where global uniqueness is required this becomes: In situations where global uniqueness is required this becomes:
Global_ID::Node_ID::Tunnel_Num::LSP_Num Global_ID::Node_ID::Tunnel_Num::LSP_Num
7.2.2.2. MEP_IDs for Pseudowires 7.2.2.2. MEP_IDs for Pseudowires
Like MPLS-TP LSPs, Pseudowire endpoints (T-PEs) require MEP_IDs. In Like MPLS-TP LSPs, Pseudowire endpoints (T-PEs) require MEP_IDs. In
order to automatically generate MEP_IDs for PWs, we simply use the order to automatically generate MEP_IDs for PWs, we simply use the
AGI plus the AII associated with that end of the PW. Thus a MEP_ID AGI plus the AII associated with that end of the PW. Thus a MEP_ID
skipping to change at page 14, line 6 skipping to change at page 16, line 41
AC_ID is the AC_ID of the Pseudowire at that node. AC_ID is the AC_ID of the Pseudowire at that node.
7.2.2.3. Pseudowire Segments Endpoint IDs 7.2.2.3. Pseudowire Segments Endpoint IDs
In some OAM communications, messages are originated by the node at In some OAM communications, messages are originated by the node at
one end of a PW segment and relayed to the other end of that same one end of a PW segment and relayed to the other end of that same
segment by setting the TTL of the PW label to one (1). For a multi- segment by setting the TTL of the PW label to one (1). For a multi-
segment pseudowire, TTL could be set to any value that would cause segment pseudowire, TTL could be set to any value that would cause
OAM messages to reach the target segment end-point (up to and OAM messages to reach the target segment end-point (up to and
including 255). In such communications an identifier for the including 255). In such communications an identifier for the
pseudowire segment endpoint. We call this a Pseudowire Segments pseudowire segment endpoint is needed. We call this a Pseudowire
Endpoint ID or PW_SE_ID. Segments Endpoint ID or PW_SE_ID.
The PW_SE_ID is formed by a combination of a PW MEP_ID and the The PW_SE_ID is formed by a combination of a PW MEP_ID and the
identification of the local node. At an S-PE, there are two PW identification of the local node. At an S-PE, there are two PW
segments. We distinguish the segments by using the MEP_ID which is segments. We distinguish the segments by using the MEP_ID which is
upstream of the PW segment in question. To complete the upstream of the PW segment in question. To complete the
identification we suffix this with the identification of the local identification we suffix this with the identification of the local
node. node.
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+
| | | | | | | | | | | | | | | |
skipping to change at page 14, line 29 skipping to change at page 17, line 18
| | | | | | | | | | | | | | | |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+
(T)PE1 (S)PE2 (S)PE3 (T)PE4 (T)PE1 (S)PE2 (S)PE3 (T)PE4
Pseudowire Maintenance Points Pseudowire Maintenance Points
For example, suppose that in the above figure all of the nodes have For example, suppose that in the above figure all of the nodes have
Global_ID GID1; the node are represented as named in the figure; and Global_ID GID1; the node are represented as named in the figure; and
The identification for the Pseudowire is: The identification for the Pseudowire is:
AGI = AGI1 AGI = AGI1
East-Global_ID = GID1 A1-Global_ID = GID1
East-Node_ID = PE1 A1-Node_ID = PE1
East-AC_ID = AII1 A1-AC_ID = AII1
West-Global_ID = GID1 Z9-Global_ID = GID1
West-Node_ID = PE4 Z9-Node_ID = PE4
West-AC_ID = AII4 Z9-AC_ID = AII4
The MEP_ID at point A would be - The MEP_ID at point A would be -
AGI1::GID1::PE1::AII1 AGI1::GID1::PE1::AII1
The PW_SE_ID at point B would be -
AGI1::GID1::PE4::AII4::GID1::PE2
The PW_SE_ID at point C would be - The PW_SE_ID at point C would be -
AGI1::GID1::PE1::AII1::GID1::PE2 AGI1::GID1::PE1::AII1::GID1::PE2
7.3. MIP Identifiers 7.3. MIP Identifiers
At a cross-connect point, in order to automatically generate MIP_IDs At a cross-connect point, in order to automatically generate MIP_IDs
for MPLS-TP, we simply use the IF_IDs of the two interfaces which are for MPLS-TP, we simply use the IF_IDs of the two interfaces which are
cross-connected via the label bindings of the MPLS-TP LSP. This cross-connected via the label bindings of the MPLS-TP LSP or PW.
allows, two MIPs to be independently identified in one node where a This allows, two MIPs to be independently identified in one node
per-interface MIP model is used. If only a per node MIP model is where a per-interface MIP model is used. If only a per node MIP
used then one MIP is configured. In this case the MIP_ID is formed model is used then one MIP is configured. In this case the MIP_ID is
using the Node_ID and an IF_Num of 0. formed using the Node_ID and an IF_Num of 0.
8. IANA Considerations 8. IANA Considerations
There are no IANA actions resulting from this document. There are no IANA actions resulting from this document.
9. Security Considerations 9. Security Considerations
This document describes an information model and, as such, does not This document describes an information model and, as such, does not
introduce security concerns. Protocol specifications that describe introduce security concerns. Protocol specifications that describe
use of this information model - however - may introduce security use of this information model, however, may introduce security risks
risks and concerns about authentication of participants. For this and concerns about authentication of participants. For this reason,
reason, the writers of protocol specifications for the purpose of the writers of protocol specifications for the purpose of describing
describing implementation of this information model need to describe implementation of this information model need to describe security
security and authentication concerns that may be raised by the and authentication concerns that may be raised by the particular
particular mechanisms defined and how those concerns may be mechanisms defined and how those concerns may be addressed.
addressed.
10. References 10. References
10.1. Normative References 10.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. [2] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G.
Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels",
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