Internet Engineering Task Force R. Martinotti
Internet-Draft D. Caviglia
Intended status: Informational Ericsson
Expires: May 21, 2009 N. Sprecher
Nokia Siemens Networks
November 17, 2008
Interworking between MPLS-TP and IP/MPLS
draft-martinotti-mpls-tp-interworking-00
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Abstract
Purpose of this ID is to illustrate interworking scenarios between
network(s) supporting MPLS-TP and network(s) supporting IP/MPLS.
Main inteworking issues and open points are highlighted.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Background . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Scope of this document . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 3
3. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4
5. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. Network Layering . . . . . . . . . . . . . . . . . . . . . 5
5.2. Network Partitioning . . . . . . . . . . . . . . . . . . . 6
6. Elements used in the figures . . . . . . . . . . . . . . . . . 6
7. Network Decomposition . . . . . . . . . . . . . . . . . . . . 7
7.1. Network Layering . . . . . . . . . . . . . . . . . . . . . 7
7.1.1. Ethernet encapsulation over MPLS-TP . . . . . . . . . 7
7.1.2. IP/MPLS encapsulation over MPLS-TP . . . . . . . . . . 10
7.1.2.1. IP/MPLS does not require PHP from MPLS-TP . . . . 10
7.1.2.2. IP/MPLS requires PHP from MPLS-TP . . . . . . . . 13
7.2. Network Partitioning . . . . . . . . . . . . . . . . . . . 15
7.2.1. Border Equipment . . . . . . . . . . . . . . . . . . . 15
7.2.1.1. Multisegment Pseudowire . . . . . . . . . . . . . 16
7.2.1.2. LSP stitching . . . . . . . . . . . . . . . . . . 18
7.2.2. Border Link . . . . . . . . . . . . . . . . . . . . . 20
7.2.2.1. Multisegment Pseudowire . . . . . . . . . . . . . 20
7.2.2.2. LSP stitching . . . . . . . . . . . . . . . . . . 23
8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 25
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 25
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
11. Security Considerations . . . . . . . . . . . . . . . . . . . 25
12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25
12.1. Normative References . . . . . . . . . . . . . . . . . . . 25
12.2. Informative References . . . . . . . . . . . . . . . . . . 25
Appendix A. Additional Stuff . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26
Intellectual Property and Copyright Statements . . . . . . . . . . 27
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1. Introduction
1.1. Background
MPLS-TP is a joint ITU-IETF effort to include a MPLS Transport
Profile within the IETF MPLS architecture to support the capabilities
and functionalities of a packet transport network as defined by
ITU-T. In the MPLS-TP requirements [draftjenkins] it is highlighted
that an MPLS-TP architecture must allow interworking with new and
already deployed IP/MPLS networks.
...
1.2. Scope of this document
This document illustrates the most likely interworking scenarios
between MPLS-TP and IP/MPLS. For each of the examined scenario
interworking limitations, issues and open points, with particular
focus on OAM capabilities, are provided.
The main architectural construct considered in this document foresees
PWE3 Protocol Stack Reference Model, however also MPLS Protocol Stack
Reference Model is presented. See [draftblb] for details.
2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC 2119].
3. Acronyms
AC Attachment circuit
CE Customer Edge
CLI Client
ETH Ethernet MAC Layer
ETY Ethernet Physical Layer
IWF Interworking Function
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LER Label Edge Router
LSP Label Switched Path
LSR Label Switch Router
MAC Media Access Control
MEP Maintenance Association End Point
MIP Maintenance Association Intermediate Point
MS-PW Multi Segment PW
NE Network Element
OAM Operations, Administration and Maintenance
PE Provider Edge
PSN Packet Switched Network
PW Pseudowire
SRV Server
SS-PW Single Segment PW
4. Problem Statement
The problem this document is addressing is the network scenarios in
which a MPLS-TP network can be interconnected with a IP/MPLS network
in different ways, such that the network decomposition can envisage
network layering and/or network partitioning.
The presented scenarios are not intended to be comprehensive, for
instance more complex scenarios can be created composing those
presented in this document.
5. Terminology
As far as this document is concerned, the following terminology is
used:
o MPLS-TP NE: a NE that supports MPLS-TP functions
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o MPLS-TP Network: a network in which MPLS-TP NEs are deployed
o IP/MPLS NE: a NE that supports IP/MPLS functions
o IP/MPLS Network: a network in which IP/MPLS NEs are deployed
For each of the scenarios described in this document, there are two
paragraphs, one related to possible issues already envisaged by the
authors (Open Issues), the other related to aspects still left for
furthr study and/or definition (open Points).
This Section provides some terminology about network layering and
partitioning. Primarily source of those definitions is [ITU-T
G.805]. Readers already familiar with these concepts can skip this
Section.
5.1. Network Layering
The following figure illustrates the Network Layering concept:
____ ___ ___ __
_/ \___/ \ _/ \___/ \_
/ \__ / \__
/===================\===+ +====/==================\
| |___O------------------O___| |
\ /\__/_ _ _ _ _ _ _ _ _ _\__/\ /
\ ___ __ / \/ \/ \ ___ _ /
\_/ \____/ \_/ | | \_/ \___/ \_/
Layer n | | Layer n
| __ __ |
| _/ \__/ \ |
| / \__ |
| / \ |
+-0| |0-+
\ /
\ __ _ /
\_/ \_/ \__/
Layer n-1
Network Layering
Figure 1
Layer n is carried over Layer n-1. Some reader will also call this
concept "Overlay model".
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5.2. Network Partitioning
The following figure illustrates the Network Partitioning concept:
___ ___ ____ ____ ___ ___
_/ \___/ \ _/ \__ _/ \___/ \ _/ \__
/ \__/ \ / \__/ \_
/ \ | / \
| Sub-Network Domain 1 |+++++| Sub-Network Domain 2 |
\ / | \ /
\ __ ___ __ _/ \ ___ ___ __ _/
\_/ \____/ \___/ \____/ \_/ \____/ \___/ \___/
Network Partitioning
Figure 2
The boundary between the two subnetworks can be a link (as defined by
[ITU-T G.805]), but also a node, which in this case SHALL be able to
handle the technologies of both subnetworks.
The two subnetworks are at the same level. Some reader will also
call this concept "Peer model".
6. Elements used in the figures
A legenda of the symbols, which are most used in the following
Sections, is provided, in order to facilitate compreension of the
scenarios.
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Equipment:
----- Direct connection
- - - Virtual connection
..... one or more direct connections
Layers:
| Termination
+ Connection
<-> Stitching
OAM:
> or < MEP
O MIP
Figure 3
7. Network Decomposition
This Section provides some interworking scenarios, using the concepts
described in Section 5.
7.1. Network Layering
In the rest of this Section the following roles applies:
o Customer network is carried over IP/MPLS (e.g. via PW
encapsulation)
o IP/MPLS network is client of MPLS-TP subnetwork
o MPLS-TP subnetwork is deployed over Ethernet, other server layers
are possible (not shown in this document)
7.1.1. Ethernet encapsulation over MPLS-TP
In this scenario the physical interface between the IP/MPLS and the
MPLS-TP network is Ethernet; the interworking is done via Ethernet
frame encapsulation in PW over MPLS-TP (as per PWE3 Protocol Stack
Reference Model).
The following figure illustrates the functional interworking among
the networks:
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Networks:
Customer Network
+---+ - - - - - - - - - - - - - - - - - - - - - - - - - +---+
| _________________________________________________ |
|/ IP/MPLS Network \|
+---------------+ - - - - - - - - - +---------------+
^ \______________|___________________|______________/
PW emulation | _________________ |
|/ MPLS-TP Network \|
+-------------------+
^ \_________________/
VPWS
Equipment:
+++++ +++++
+ 1 +----+ - - - - - - - - - - - - - - - - - - - - - - - +----+ 9 +
+++++ | | +++++
CE +++++ +++++ +++++ +++++ CE
+ 2 +...+ 3 +-----+- - - - - - - -+-----+ 7 +...+ 8 +
+++++ +++++ | | +++++ +++++
LER LSR +++++ +++++ +++++ LSR LER
PE CE + 4 +...+ 5 +...+ 6 + PE
+++++ +++++ +++++
LER LSR LER
PE PE
Ethernet encapsulation - Networks view
Figure 4
The LSR 3 and 7 are one hop away from the IP/MPLS layer point of
view, thus there is no interaction between the control plane of IP/
MPLS and MPLS-TP.
The service provided by the MPLS-TP network is an E-Line service
realized via VPWS, thus the LER4 and 6 are unaware that above the
Ethernet layer there is a MPLS LSP.
The following figure illustrates the stacking relationship among the
technology layers and OAM relationship among the networks:
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Layers:
|--------+----------------------CLI----------------------+--------|
|--SRV--| |---------------------PW----------------------| |--SRV--|
|------+--------------LSP--------------+------|
|-ETH-| |------+------ETH------+------| |-ETH-|
|-ETY-| |-ETY-| |-----PW------| |-ETY-| |-ETY-|
|-----LSP-----|
|-ETH-| |-ETH-|
|-ETY-| |-ETY-|
OAM:
(9) >----O-------------------------------------------------O----< CLI
(8) >-----------------------------------------------< CLI
(7) >-------------------------------------------< PW
(6) >------O-----------------------------O------< LSP
(5) >----O-----------------O----< ETH
(4) >O-------------O< ETH
(3) >-----------< PW
(2) >-----------< LSP
(1) > -< > - < >---< > - < > - < >---< > - < >- < PHY
Equipment:
+++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++
+ 1 +--+ 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 +---+ 7 +...+ 8 +--+ 9 +
+++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++
CE LER LSR LER LSR LER LSR LER CE
Ethernet encapsulation - Layers and OAM view
Figure 5
Several levels of OAM are shown in the previous figure, these are not
comprehensive (e.g. Ethernet OAM defines several levels for each
layer), any subset of them MAY be configured in a network. A brief
description of the different levels is provided:
(9) End-to-End Client level OAM on Client network
(8) Edge-to-Edge Client level OAM on IP/MPLS network
(7) Edge-to-Edge MPLS OAM on IP/MPLS network (at PW level)
(6) Edge-to-Edge MPLS OAM on IP/MPLS network (at LSP level)
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(5) Router-to-Router Eth OAM on IP/MPLS network
(4) Edge-to-Edge Eth OAM on MPLS-TP network
(3) Edge-to-Edge MPLS OAM on MPLS-TP network (at PW level)
(2) Edge-to-Edge MPLS OAM on MPLS-TP network (at LSP level)
(1) Physical level OAM (MAY be of several kind)
Note that the OAM layers not directly related to MPLS-TP network have
been reported just for completeness of the scenario, however their
behaviour and interworking are out of scope of this document.
Open Issues:
o None up to now
Open Points:
o Inteworking between LSP OAM (2) and ETH OAM (3) and/or (4) is
still to be cleared/defined
7.1.2. IP/MPLS encapsulation over MPLS-TP
In this scenario the physical interface between the IP/MPLS and the
MPLS-TP network MAY be Ethernet; the interworking is done via client
LSP encapsulation over MPLS-TP (as per MPLS Protocol Stack Reference
Model).
The following main features SHOULD be taken into account:
o Interaction at Data Plane
o Possible support of Management Plane of client MPLS Layer
o Possible support of Control Plane of client MPLS Layer
o Possible handling of PHP of client MPLS Layer
7.1.2.1. IP/MPLS does not require PHP from MPLS-TP
In this scenario the edge nodes of the MPLS-TP subnetwork are one hop
away from no client node (of the IP/MPLS network) requiring PHP.
The following figure illustrates the functional interworking among
the networks.
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IP/MPLS network does not require PHP from MPLS-TP
Networks:
Customer Network
+---+ - - - - - - - - - - - - - - - - - - - - - - - - - +---+
| _________________________________________________ |
|/ IP/MPLS Network \|
+---------------+ - - - - - - - - - +---------------+
^ \______________|___________________|______________/
PW emulation | _________________ |
|/ MPLS-TP Network \|
+-------------------+
^ \_________________/
MPLS VPN
Equipment:
+++++ +++++
+ 1 +----+ - - - - - - - - - - - - - - - - - - - - - - - +----+ 9 +
+++++ | | +++++
CE +++++ +++++ +++++ +++++ +++++ +++++ CE
+ 2 +...+ 3 +---+ +- - - - - -+ +---+ 7 +...+ 8 +
+++++ +++++ + + + + +++++ +++++
LER LSR +LSR+ +++++ +LSR+ LSR LER
PE + 4 +...+ 5 +...+ 6 + PE
+++++ +++++ +++++
LER LSR LER
IP/MPLS encapsulation over MPLS-TP - Networks view
Figure 6
The equipment 4 and 6 in the above figure act as dual function:
o LSR of client IP/MPLS network
o LER of server MPLS-TP subnetwork
The following figure illustrates the stacking relationship among the
technology layers and OAM relationship among the networks:
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IP/MPLS network does not require PHP from MPLS-TP
Layers:
|--------+----------------------CLI----------------------+--------|
|--SRV--| |---------------------PW----------------------| |--SRV--|
|------+-------+------LSP------+-------+------|
|-ETH-| |-ETH-| |-----LSP-----| |-ETH-| |-ETH-|
|-ETY-| |-ETY-| |-ETH-| |-ETH-| |-ETY-| |-ETY-|
|-ETY-| |-ETY-|
OAM:
(6) >----O-------------------------------------------------O----< CLI
(5) >-----------------------------------------------< CLI
(4) >-------------------------------------------< PW
(3) >--------------O-------------O--------------< LSP
(2) >-----------< LSP
(1) >--< > - < >---< > - < > - < >---< > - < >--< PHY
Equipment:
+++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++
+ 1 +--+ 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 +---+ 7 +...+ 8 +--+ 9 +
+++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++
CE LER LSR LER LSR LER LSR LER CE
IP/MPLS encapsulation over MPLS-TP - Layers and OAM view
Figure 7
A not comprehensive set of OAM is shown in the previous figure, the
same generic assumptions as in Section 7.1.1 are considered. A brief
description of the different levels is provided:
(6) End-to-End Client level OAM on Client network
(5) Edge-to-Edge Client level OAM on IP/MPLS network
(4) Edge-to-Edge MPLS OAM on IP/MPLS network (at PW level)
(3) Edge-to-Edge MPLS OAM on IP/MPLS network (at LSP level)
(2) Edge-to-Edge MPLS OAM on MPLS-TP network (at LSP level)
(1) Physical level OAM (MAY be of several kind)
Open Issues:
o None up to now
Open Points:
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o Inteworking between LSP OAM (2) and LSP OAM (3) is still to be
cleared/defined
7.1.2.2. IP/MPLS requires PHP from MPLS-TP
In this scenario the edge nodes of the MPLS-TP subnetwork are one hop
away from at least one client node (of the IP/MPLS network) requiring
PHP.
The following figure illustrates the functional interworking among
the networks:
IP/MPLS requires PHP from MPLS-TP
Networks:
Customer Network
+---+ - - - - - - - - - - - - - - - - - - - - - - +---+
| ___________________________________________ |
|/ IP/MPLS Network (PHP)-> \|
+---------------+ - - - - - - - - - +---------+
^ \______________|___________________|________/
PW emulation | _________________ |
|/ MPLS-TP Network \|
+-------------------+
^ \_________________/
MPLS VPN
Equipment:
+++++ +++++
+ 1 +----+ - - - - - - - - - - - - - - - - - - - - +----+ 8 +
+++++ | (PHP)-> | +++++
CE +++++ +++++ +++++ +++++ +++++ CE
+ 2 +...+ 3 +---+ +- - - - - -+ +-----+ 7 +
+++++ +++++ + + + + +++++
LER LSR +LSR+ +++++ +LSR+ LER
PE + 4 +...+ 5 +...+ 6 + PE
+++++ +++++ +++++
LER LSR LER
IP/MPLS encapsulation over MPLS-TP - Network view
Figure 8
The equipment 4 and 6 in the above figure act as dual function:
o LSR of client IP/MPLS network
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o LER of server MPLS-TP subnetwork
As equipment 8 of client IP/MPLS network requires PHP, equipment 6
which act as penultimate hop is required to drop LSP label of client
IP/MPLS tunnel (indicated in direction from center to right on
equipment number 6).
The following figure illustrates the stacking relationship among the
technology layers and OAM relationship among the networks:
IP/MPLS requires PHP from MPLS-TP
Layers:
|--------+----------------------CLI----------------+--------|
|--SRV--| |---------------------PW------(PHP)->---| |--SRV--|
|------+-------+------LSP-----| |--ETH--|
|-ETH-| |-ETH-| |-----LSP-----| |--ETY--|
|-ETY-| |-ETY-| |-ETH-| |-ETH-|
|-ETY-| |-ETY-|
OAM:
(5) >----O-------------------------------------------O----< CLI
(4) >-----------------------------------------< CLI
(3) >-------------O---------------?-------< PW
(2) >-----------< LSP
(1) >--< > - < >---< > - < > - < >-----< >--< PHY
Equipment:
+++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++
+ 1 +--+ 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 +-----+ 7 +--+ 8 +
+++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++
CE LER LSR LER LSR LER LER CE
IP/MPLS encapsulation over MPLS-TP - Layers and OAM view
Figure 9
A not comprehensive set of OAM is shown in the previous figure, the
same generic assumptions as in Section 7.1.1 are considered. A brief
description of the different levels is provided:
(5) End-to-End Client level OAM on Client network
(4) Edge-to-Edge Client level OAM on IP/MPLS network
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(3) Edge-to-Edge MPLS OAM on IP/MPLS network (at PW level)
(2) Edge-to-Edge MPLS OAM on MPLS-TP network (at LSP level)
(1) Physical level OAM (MAY be of several kind)
Open Issues:
o As in the IP/MPLS network the LSP, which is tunneled over MPLS-TP
network, is terminated on an equipment requiring PHP (Equipment n.
8), IP/MPLS OAM cannot be used at LSP level, so monitoring can be
performed at PW level. Interworking between MPLS-TP OAM and IP/
MPLS on node 6 MAY be performed, but its deteils are out of scope
of this document.
Open Points:
o Inteworking between LSP OAM (2) and PW OAM (3) is still to be
cleared/defined
7.2. Network Partitioning
In the rest of this Section the following roles applies:
o Customer network is carried partly over IP/MPLS subnetwork (e.g.
via PW encapsulation) and partly over MPLS-TP subnetwork.
For the purposes of this Section, MPLS-TP subnetwork is deployed
between a CE and an IP/MPLS subnetwork. Other kind of deployment are
possible (not shown in this document), for instance:
o More than two subnetworks are deployed between the CEs
o MPLS-TP can be deployed between two subnetworks
7.2.1. Border Equipment
Main features to be taken into account:
o MultiSegment Pseudowire
o LSP Stitching
o Network Interworking
o End-to-End OAM support
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o Interaction at Data Plane
o Interaction at Management Plane
o Possible interaction at Control Plane
o Non need of PHP handling of client MPLS Layer
7.2.1.1. Multisegment Pseudowire
The following figure illustrates the functional interworking among
the networks:
Networks:
Customer Network
+---+ - - - - - - - - - - - - - - - - - +---+
| _______________ _______________ |
|/ IP/MPLS Net. \ / MPLS-TP Net. \|
+-----------------+-----------------+
^ \_______________/ \_______________/
PW emulation
PWs:
|-------------MS-PW-------------|
|---------------|---------------|
^ ^
PW segments
Equipment:
+++++ +++++
+ 1 +----+- - - - - - - - - - - - - - - -+----+ 7 +
+++++ | | +++++
CE +++++ +++++ +++++ +++++ +++++ CE
+ 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 +
+++++ +++++ +++++ +++++ +++++
LER LSR LER LSR LER
T-PE S-PE T-PE
Border Equipment - Multisegment Pseudowire - Networks and PWs view
Figure 10
The following figure illustrates the stacking relationship among the
technology layers and OAM relationship among the networks:
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Layers:
|--------+--------------CLI--------------+--------|
|--SRV--| |---------PW---+--------------| |--SRV--|
|-----LSP-----| |-----LSP-----|
|-ETH-| |-ETH-| |-ETH-| |-ETH-|
|-ETY-| |-ETY-| |-ETY-| |-ETY-|
OAM:
(5) >----O---------------------------------O----< CLI
(4) >-------------------------------< CLI
(3) >-------------O-------------< MS-PW
(2) >-----------< >-----------< LSP
(1) >--< > - < >---< > - < > - < >--< PHY
Equipment:
+++++ +++++ +++++ +++++ +++++ +++++ +++++
+ 1 +--+ 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 +--+ 7 +
+++++ +++++ +++++ +++++ +++++ +++++ +++++
CE LER LSR LER LSR LER CE
Border Equipment - Multisegment Pseudowire - Layers and OAM view
Figure 11
A not comprehensive set of OAM is shown in the previous figure, the
same generic assumptions as in Section 7.1.1 are considered. A brief
description of the different levels is provided:
(5) End-to-End Client level OAM on Client network
(4) Edge-to-Edge Client level OAM on partitioned network
(3) Edge-to-Edge MPLS OAM on partitioned network (at PW level)
(2) Edge-to-Edge MPLS OAM on partitioned network (at LSP level)
(1) Physical level OAM (MAY be of several kind)
Open Issues:
o None up to now
Open Points:
o Inteworking between LSP OAM (2) and MS-PW OAM (3) is still to be
cleared/defined
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o Edge-to-Edge Client level OAM (4) must be configuerd on different
subnetworks
7.2.1.2. LSP stitching
The following figure illustrates the functional interworking among
the networks:
Networks:
Customer Network
+---+ - - - - - - - - - - - - - - - - - +---+
| _______________ _______________ |
|/ IP/MPLS Net. \ / MPLS-TP Net. \|
+-----------------+-----------------+
^ \_______________/ \_______________/
PW emulation
PWs:
|-------------SS-PW-------------|
Equipment:
+++++ +++++
+ 1 +----+- - - - - - - - - - - - - - - -+----+ 9 +
+++++ | | +++++
CE +++++ +++++ +++++ +++++ +++++ CE
+ 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 +
+++++ +++++ +++++ +++++ +++++
LER LSR LER LSR LER
PE PE
Border Equipment - LSP stitching - Networks and PWs view
Figure 12
The following figure illustrates the stacking relationship among the
technology layers and OAM relationship among the networks:
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Layers:
|--------+--------------CLI--------------+--------|
|--SRV--| |--------------PW-------------| |--SRV--|
|-------------<->-LSP---------|
|-ETH-| |-ETH-| |-ETH-| |-ETH-|
|-ETY-| |-ETY-| |-ETY-| |-ETY-|
OAM:
(6) >----O---------------------------------O----< CLI
(5) >-------------------------------< CLI
(4) >---------------------------< PW
(3) >-------------O-------------< LSP
(2) >-----------< >-----------< TCM
(1) >--< > - < >---< > - < > - < >--< PHY
Equipment:
+++++ +++++ +++++ +++++ +++++ +++++ +++++
+ 1 +--+ 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 +--+ 7 +
+++++ +++++ +++++ +++++ +++++ +++++ +++++
CE LER LSR LER LSR LER CE
Border Equipment - LSP stitching - Layers and OAM view
Figure 13
Note: in this case a SS-PW extends over the subnetworks as the
stitched LSP does. TCM can be used to monitor the LSP segments.
A not comprehensive set of OAM is shown in the previous figure, the
same generic assumptions as in Section 7.1.1 are considered. A brief
description of the different levels is provided:
(6) End-to-End Client level OAM on Client network
(5) Edge-to-Edge Client level OAM on partitioned network
(4) Edge-to-Edge MPLS OAM on partitioned network (at PW level)
(3) Edge-to-Edge MPLS OAM on partitioned network (at LSP level)
(2) Edge-to-Edge MPLS OAM on partitioned network (at TCM level)
(1) Physical level OAM (MAY be of several kind)
Open Issues:
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o None up to now
Open Points:
o Inteworking between TCM OAM (2) and LSP OAM (3) is still to be
cleared/defined
7.2.2. Border Link
Main features to be taken into account:
o MultiSegment Pseudowire
o LSP Stitching
o Interaction at Data Plane
o Interaction at Management Plane
o Possible interaction at Control Plane
o Possible PHP handling of client MPLS Layer
7.2.2.1. Multisegment Pseudowire
The following figure illustrates the functional interworking among
the networks:
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Networks:
Customer Network
+---+ - - - - - - - - - - - - - - - - - -+---+
| ___________ ______________ |
|/IP/MPLS N. \ / MPLS-TP N. \|
+-------------+-----+----------------+
^ \___________/ \______________/
PW emulation
PWs:
|------------MS-PW--------------|
|-----------|-----|-------------|
^ ^ ^
PW segments
Equipment:
+++++ +++++
+ 1 +----+- - - - - - - - - - - - - - - -+----+ 6 +
+++++ | | +++++
CE +++++ +++++ +++++ +++++ CE
+ 2 +.....+ 3 +-----+ 4 +.......+ 5 +
+++++ +++++ +++++ +++++
LER LER LER LER
T-PE S-PE S-PE T-PE
Border Link - Multisegment Pseudowire - Networks view
Figure 14
The following figure illustrates the stacking relationship among the
technology layers and OAM relationship among the networks:
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Layers:
|--------+-------------CLI---------------+--------|
|--SRV--| |--------+----PW---+----------| |--SRV--|
|--LSP--| |--LSP--| |---LSP---|
|- ETH -| |--ETH--| |- -ETH- -|
|- ETY -| |--ETY--| |- -ETY- -|
OAM:
(5) >----O---------------------------------O----< CLI
(4) >-------------------------------< CLI
(3) >-------O---------O---------< MS-PW
(2) >-----< >-----< >-------< LSP
(1) >--< > - - < >-----< > - - - < >--< PHY
Equipment:
+++++ +++++ +++++ +++++ +++++ +++++
+ 1 +--+ 2 +.....+ 3 +-----+ 4 +.......+ 5 +--+ 6 +
+++++ +++++ +++++ +++++ +++++ +++++
CE LER LER LER LER CE
Border Link - Multisegment Pseudowire - Layers and OAM view
Figure 15
A not comprehensive set of OAM is shown in the previous figure, the
same generic assumptions as in Section 7.1.1 are considered. A brief
description of the different levels is provided:
(5) End-to-End Client level OAM on Client network
(4) Edge-to-Edge Client level OAM on partitioned network
(3) Edge-to-Edge MPLS OAM on partitioned network (at PW level)
(2) Edge-to-Edge MPLS OAM on partitioned network (at LSP level)
(1) Physical level OAM (MAY be of several kind)
Open Issues:
o None up to now
Open Points:
o Inteworking between LSP OAM (2) and MS-PW OAM (3) is still to be
cleared/defined
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7.2.2.2. LSP stitching
The following figure illustrates the functional interworking among
the networks:
Networks:
Customer Network
+---+ - - - - - - - - - - - - - - - - - -+---+
| ___________ ______________ |
|/IP/MPLS N. \ / MPLS-TP N. \|
+-------------+-----+----------------+
^ \___________/ \______________/
PW emulation
PWs:
|------------SS-PW--------------|
Equipment:
+++++ +++++
+ 1 +----+- - - - - - - - - - - - - - - -+----+ 6 +
+++++ | | +++++
CE +++++ +++++ +++++ +++++ CE
+ 2 +.....+ 3 +-----+ 4 +.......+ 5 +
+++++ +++++ +++++ +++++
LER LER LER LER
PE PE
Border Link - LSP stitching - Networks view
Figure 16
The following figure illustrates the stacking relationship among the
technology layers and OAM relationship among the networks:
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Layers:
|--------+-------------CLI---------------+--------|
|--SRV--| |-------------PW--------------| |--SRV--|
|-------<->--LSP--<->---------|
|- ETH -| |--ETH--| |- -ETH- -|
|- ETY -| |--ETY--| |- -ETY- -|
OAM:
(6) >----O---------------------------------O----< CLI
(5) >-------------------------------< CLI
(4) >---------------------------< SS-PW
(3) >-------O---------O---------< LSP
(2) >-----< >-----< >-------< TCM
(1) >--< > - - < >-----< > - - - < >--< PHY
Equipment:
+++++ +++++ +++++ +++++ +++++ +++++
+ 1 +--+ 2 +.....+ 3 +-----+ 4 +.......+ 5 +--+ 6 +
+++++ +++++ +++++ +++++ +++++ +++++
CE LER LER LER LER CE
Border Link - LSP stitching - Layers and OAM view
Figure 17
Note: in this case a SS-PW extends over the subnetworks as the
stitched LSP does. TCM can be used to monitor the LSP segments.
A not comprehensive set of OAM is shown in the previous figure, the
same generic assumptions as in Section 7.1.1 are considered. A brief
description of the different levels is provided:
(6) End-to-End Client level OAM on Client network
(5) Edge-to-Edge Client level OAM on partitioned network
(4) Edge-to-Edge MPLS OAM on partitioned network (at PW level)
(3) Edge-to-Edge MPLS OAM on partitioned network (at LSP level)
(2) Edge-to-Edge MPLS OAM on partitioned network (at TCM level)
(1) Physical level OAM (MAY be of several kind)
Open Issues:
o None up to now
Open Points:
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o Inteworking between TCM OAM (2) and LSP OAM (3) is still to be
cleared/defined
8. Conclusions
This document has illustrated some interworking scenarios between
MPLS-TP and IP/MPLS. Where open points and open issues are still
present, the reader is invited to contribute to their resolution.
9. Acknowledgements
The authors gratefully acknowledge the input of Attila Takacs.
10. IANA Considerations
This memo includes no request to IANA.
11. Security Considerations
All drafts are required to have a security considerations section.
See bla bla bla...
12. References
12.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
12.2. Informative References
[RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
Label Switching Architecture", RFC 3031, January 2001.
[draftjenkins]
Niven-Jenkins, B., Brungard, D., and M. Betts, "MPLS-TP
Requirements",
ID draft-jenkins-mpls-mpls-tp-requirements-00, July 2008.
[draftblb]
Bocci, M., Lasserre, M., and S. Bryant, "A Framework for
MPLS in Transport Networks",
ID draft-blb-mpls-tp-framework-00, July 2008.
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[draftvigoureux]
Vigoureux, M., "Requirements for OAM in MPLS Transport
Networks", ID draft-vigoureux-mpls-tp-oam-requirements-00,
June 2008.
Appendix A. Additional Stuff
This becomes an Appendix.
Authors' Addresses
Riccardo Martinotti
Ericsson
Via A. Negrone 1/A
Genova - Sestri Ponente 16153
Italy
Email: riccardo.martinotti@ericsson.com
Diego Caviglia
Ericsson
Via A. Negrone 1/A
Genova - Sestri Ponente 16153
Italy
Email: diego.caviglia@ericsson.com
Nurit Sprecher
Nokia Siemens Networks
3 Hanagar St. Neve Ne'eman B
Hod Hasharon 45241
Israel
Email: nurit.sprecher@nsn.com
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