Internet Engineering Task Force R. Martinotti Internet-Draft D. Caviglia Intended status: Informational Ericsson Expires: September 6, 2009 N. Sprecher Nokia Siemens Networks A. D'Alessandro A. Capello Telecom Italia March 5, 2009 Interworking between MPLS-TP and IP/MPLS draft-martinotti-mpls-tp-interworking-01 Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 6, 2009. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Martinotti, et al. Expires September 6, 2009 [Page 1] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 Abstract Purpose of this ID is to illustrate interworking scenarios between network(s) supporting MPLS-TP and network(s) supporting IP/MPLS. Main interworking issues and open points are highlighted. 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 . . . . . . . . . . . . . . . . . . . . . . . . . 5 5.1. Network Layering . . . . . . . . . . . . . . . . . . . . . 5 5.2. Network Partitioning . . . . . . . . . . . . . . . . . . . 6 6. Elements used in the figures . . . . . . . . . . . . . . . . . 7 7. Network Decomposition . . . . . . . . . . . . . . . . . . . . 7 7.1. Network Layering . . . . . . . . . . . . . . . . . . . . . 7 7.1.1. Ethernet encapsulation over MPLS-TP . . . . . . . . . 8 7.1.2. Transparent transport of IP/MPLS . . . . . . . . . . . 10 7.1.3. IP/MPLS / MPLS-TP hybrid edge node . . . . . . . . . . 13 7.1.3.1. IP/MPLS does not require PHP from MPLS-TP . . . . 13 7.1.3.2. IP/MPLS requires PHP from MPLS-TP . . . . . . . . 16 7.2. Network Partitioning . . . . . . . . . . . . . . . . . . . 18 7.2.1. Border Node . . . . . . . . . . . . . . . . . . . . . 19 7.2.1.1. Multisegment Pseudowire . . . . . . . . . . . . . 19 7.2.1.2. LSP stitching . . . . . . . . . . . . . . . . . . 22 7.2.2. Border Link . . . . . . . . . . . . . . . . . . . . . 24 7.2.2.1. Multisegment Pseudowire . . . . . . . . . . . . . 24 7.2.2.2. LSP stitching . . . . . . . . . . . . . . . . . . 27 8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 29 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 29 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 11. Security Considerations . . . . . . . . . . . . . . . . . . . 29 12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29 12.1. Normative References . . . . . . . . . . . . . . . . . . . 29 12.2. Informative References . . . . . . . . . . . . . . . . . . 30 Appendix A. Additional Stuff . . . . . . . . . . . . . . . . . . 30 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 30 Martinotti, et al. Expires September 6, 2009 [Page 2] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 1. Introduction 1.1. Background MPLS-TP is a joint ITU-IETF effort to include the 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 [draft jenkins] 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 scenarios 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 used. See [draft mpls-tp framework] for details. Note: due to the early level of definition of CP of MPLS-TP, any possible interaction between CP of IP/MPLS and CP of MPLS-TP is left for further study. 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 [RFC2119]. 3. Acronyms AC Attachment circuit CE Customer Edge CLI Client CP Control Plane DP Data Plane Martinotti, et al. Expires September 6, 2009 [Page 3] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 ETH Ethernet MAC Layer ETY Ethernet Physical Layer IWF Interworking Function 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 MP Management Plane MS-PW Multi Segment PW NE Network Element OAM Operations, Administration and Maintenance PE Provider Edge PHY Physical Layer PSN Packet Switched Network PW Pseudowire SRV Server SS-PW Single Segment PW S-PE Switching Provider Edge T-PE Terminating Provider Edge 4. Problem Statement This document addresses interworking issues between MPLS-TP network and IP/MPLS network. The network decomposition can envisage network layering and/or network partitioning. Martinotti, et al. Expires September 6, 2009 [Page 4] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 The presented scenarios are not intended to be comprehensive, for instance more complex scenarios can be created composing those described in this document. 5. Terminology As far as this document is concerned, the following terminology is used: o IP/MPLS NE: a NE that supports IP/MPLS functions o IP/MPLS Network: a network in which IP/MPLS NEs are deployed o MPLS-TP NE: a NE that supports MPLS-TP functions o MPLS-TP Network: a network in which MPLS-TP NEs are deployed o Node: either MPLS-TP NE, IP/MPLS NE or CE o Ingress direction: from client to network o Egress direction: from network to client For each of the scenarios described in this document, two paragraphs may appear, one related to possible issues already envisaged by the authors (Open Issues), the other related to aspects still left for further 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: Martinotti, et al. Expires September 6, 2009 [Page 5] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 ____ ___ ___ __ _/ \___/ \ _/ \___/ \_ / \__ / \__ /===================\===+ +====/==================\ | |___O------------------O___| | \ /\__/_ _ _ _ _ _ _ _ _ _\__/\ / \ ___ __ / \/ \/ \ ___ _ / \_/ \____/ \_/ | | \_/ \___/ \_/ Layer n | | Layer n | __ __ | | _/ \__/ \ | | / \__ | | / \ | ____ +-0| |0-+ \__/ Adaptation \ / \ __ _ / __ \_/ \_/ \__/ \/ Termination Layer n-1 Network Layering Figure 1 Layer n is carried over Layer n-1, via adaptation and termination functions. Some readers will also call this concept "Overlay model". 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 Martinotti, et al. Expires September 6, 2009 [Page 6] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 [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 readers 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 comprehension of the scenarios. Node: ----- 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 assumptions apply: o Customer network is carried over IP/MPLS (e.g. via PW encapsulation) o IP/MPLS network is client of MPLS-TP subnetwork Martinotti, et al. Expires September 6, 2009 [Page 7] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 7.1.1. Ethernet encapsulation over MPLS-TP IP/MPLS network is deployed over Ethernet (at least on interfaces interconnecting to the MPLS-TP subnetwork). The interworking is done via Ethernet frame encapsulation in PW over MPLS-TP (as per PWE3 Protocol Stack Reference Model). MPLS-TP LSPs are pre-configured with respect to IP/MPLS LSPs and may be seen as forwarding adjacencies by IGP instance of IP/MPLS networks. The following figure illustrates the functional interworking among the networks: Networks: Customer Network +---+ - - - - - - - - - - - - - - - - - - - - - - - - - +---+ | _________________________________________________ | |/ IP/MPLS Network \| +---------------+ - - - - - - - - - +---------------+ ^ \______________|___________________|______________/ PW emulation | _________________ | |/ MPLS-TP Network \| +-------------------+ ^ \_________________/ PW emulation (VPWS) Nodes: +++++ +++++ + 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, CP/MP of IP/MPLS is transparently transported by MPLS-TP network. Martinotti, et al. Expires September 6, 2009 [Page 8] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 The service provided by the MPLS-TP network could be an E-Line service realized via VPWS in case of port based service interface and p2p connectivity between LSR 3 and LSR 7 or multiple E-Line services in case of VLAN based service interface (e.g. LSR3 could be connected to more that one LSRs through the MPLS-TP network). In both of the above cases the LER4 and 6 do not need to know that above the Ethernet layer there is an MPLS LSP. The following figure illustrates the stacking relationship among the technology layers and OAM relationship among the networks: Layers: |--------+----------------------CLI----------------------+--------| |--SRV--| |---------------------PW----------------------| |--SRV--| |------+--------------LSP--------------+------| |-ETH-| |------+----ETH--------+------| |-ETH-| |-ETY-| |-ETY-| |------PW-----| |-ETY-| |-ETY-| |--LSP-+------| |-ETH-| |-ETH-| |-ETY-| |-ETY-| OAM: (6) >-------------------------------------------< PW (5) >------O-----------------------------O------< LSP (4) >----O-----------------O----< ETH (3) >-----------< PW (2) >-----O-----< LSP (1) >--< >...< >---< >...< >...< >---< >...< >--< PHY Nodes: +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ + 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) and any subset of them MAY be configured in a network. A brief description of the different levels is provided: Martinotti, et al. Expires September 6, 2009 [Page 9] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 (6) Edge-to-Edge MPLS OAM on IP/MPLS network (at PW level) (5) Edge-to-Edge MPLS OAM on IP/MPLS network (at LSP level) (4) Router-to-Router Eth OAM on IP/MPLS network (3) Edge-to-Edge MPLS-TP OAM on MPLS-TP network (at PW level) (2) Edge-to-Edge MPLS-TP OAM on MPLS-TP network (at LSP level) (1) Physical level OAM (MAY be of several kinds) 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 Points: o Interworking between LSP OAM (2), PW OAM (3) and ETH OAM (4) is still to be cleared/defined; it could imply fault indication, alarm suppression, etc. 7.1.2. Transparent transport of IP/MPLS In this scenario the physical interface between the IP/MPLS and the MPLS-TP network is generic and may be other that Ethernet (e.g. POS); the interworking is done via client LSP packet encapsulation in PW over MPLS-TP (as per PWE3 Protocol Stack Reference Model). MPLS-TP LSPs are pre-configured with respect to IP/MPLS LSPs and may be seen as forwarding adjacencies by IGP instance of IP/MPLS networks. The following figure illustrates the functional interworking among the networks: Martinotti, et al. Expires September 6, 2009 [Page 10] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 Networks: Customer Network +---+ - - - - - - - - - - - - - - - - - - - - - - - - - +---+ | _________________________________________________ | |/ IP/MPLS Network \| +---------------+ - - - - - - - - - +---------------+ ^ \______________|___________________|______________/ PW emulation | _________________ | |/ MPLS-TP Network \| +-------------------+ ^ \_________________/ PW emulation Nodes: +++++ +++++ + 1 +----+ - - - - - - - - - - - - - - - - - - - - - - - +----+ 9 + +++++ | | +++++ CE +++++ +++++ +++++ +++++ CE + 2 +...+ 3 +-----+- - - - - - - -+-----+ 7 +...+ 8 + +++++ +++++ | | +++++ +++++ LER LSR +++++ +++++ +++++ LSR LER PE CE + 4 +...+ 5 +...+ 6 + PE +++++ +++++ +++++ LER LSR LER PE PE Transparent transport of IP/MPLS - Networks view Figure 6 The LSR 3 and 7 are one hop away from the IP/MPLS layer point of view. The service provided by the MPLS-TP network is p2p; client traffic is separated on a per port basis, so that all traffic coming from interface toward LSR 3 is transparently transported to LSR 7 and viceversa. The client traffic to be encapsulated is both client MPLS packet (client DP) and IP packet (client CP and MP), encapsulation is performed via PWs, that is, one PW is needed for the DP (LSP) and one for the CP/MP (IP). An LSP for IP packets devoted for CP must be pre-configured in order to enable the interworking scenario. If CP interaction between IP/ MPLS and MPLS-TP is not enabled then the LSP for carrying out MPLS packets (client DP) must be pre-configured. The following figure illustrates the stacking relationship among the Martinotti, et al. Expires September 6, 2009 [Page 11] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 technology layers and OAM relationship among the networks: Layers: |--------+----------------------CLI----------------------+--------| |--SRV--| |---------------------PW----------------------| |--SRV--| |------+-------+------LSP------+-------+------| |-SRV-| |-SRV-| |---PW--------| |-SRV-| |-SRV-| |--LSP-+------| |-ETH-| |-ETH-| |-ETY-| |-ETY-| OAM: (5) >-------------------------------------------< PW (4) >------O-----------------------------O------< LSP (3) >-----------< PW (2) >-----O-----< LSP (1) >---< >...< >...< >---< PHY Nodes: +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ + 1 +--+ 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 +---+ 7 +...+ 8 +--+ 9 + +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ CE LER LSR LER LSR LER LSR LER CE Transparent transport of IP/MPLS - Layers and OAM view Figure 7 Several levels of OAM are possible, a subset of them is shown in the previous figure, however these are not comprehensive, any subset of them MAY be configured in a network. A brief description of the levels is provided: (5) Edge-to-Edge MPLS OAM on IP/MPLS network (at PW level) (4) Edge-to-Edge MPLS OAM on IP/MPLS network (at LSP level) (3) Edge-to-Edge MPLS-TP OAM on MPLS-TP network (at PW level) (2) Edge-to-Edge MPLS-TP OAM on MPLS-TP network (at LSP level) (1) Physical level OAM (MAY be of several kinds) Open Points: Martinotti, et al. Expires September 6, 2009 [Page 12] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 o This scenario needs the definition of MPLS packets and IP packets encapsulation in PW. o Interworking between MPLS-TP network OAM ((2), (3)) and IP/MPLS network OAM ((4), (5)) is still to be cleared/defined; it could imply fault indication, alarm suppression, etc. o Interaction between IP/MPLS and MPLS-TP CPs is still to be cleared/defined 7.1.3. IP/MPLS / MPLS-TP hybrid edge node The following main features SHOULD be taken into account: o Two or more client interfaces MAY be involved in the service o Peering of client DP (label swapping of client MPLS packets) o Possible tunneling of MP of client MPLS Layer o Possible peering/tunneling CP of client MPLS Layer o Possible handling of PHP of client MPLS Layer 7.1.3.1. 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 the client node of the IP/MPLS network. The following figure illustrates the functional interworking among the networks. Martinotti, et al. Expires September 6, 2009 [Page 13] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 IP/MPLS network does not require PHP from MPLS-TP Networks: Customer Network +---+ - - - - - - - - - - - - - - - - - - - - - - - - - +---+ | _________________________________________________ | |/ IP/MPLS Network \| +---------------+ - - - - - - - - - +---------------+ ^ \______________|___________________|______________/ PW emulation | _________________ | |/ MPLS-TP Network \| +-------------------+ ^ \_________________/ PW emulation Nodes: +++++ +++++ + 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 8 The Node 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 Note that this scenario needs the definition of MPLS packets and IP packets encapsulation in PW (to be discussed, see Open Points). The following figure illustrates the stacking relationship among the technology layers and OAM relationship among the networks: Martinotti, et al. Expires September 6, 2009 [Page 14] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 IP/MPLS network does not require PHP from MPLS-TP Layers: |--------+----------------------CLI----------------------+--------| |--SRV--| |---------------------PW----------------------| |--SRV--| |------+-------+------LSP------+-------+------| |-SRV-| |-SRV-| |------PW-----| |-SRV-| |-SRV-| |-LSP--+------| |-ETH-| |-ETH-| |-ETY-| |-ETY-| OAM: (5) >-------------------------------------------< PW (4) >--------------O-------------O--------------< LSP (3) >-----------< PW (2) >-----O-----< LSP (1) >---< >...< >...< >---< PHY Nodes: +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ + 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 9 Several levels of OAM are possible, a subset of them is shown in the previous figure, however these are not comprehensive, any subset of them MAY be configured in a network. A brief description of the levels is provided: (5) Edge-to-Edge MPLS OAM on IP/MPLS network (at PW level) (4) Edge-to-Edge MPLS OAM on IP/MPLS network (at LSP level) (3) Edge-to-Edge MPLS-TP OAM on MPLS-TP network (at PW level) (2) Edge-to-Edge MPLS-TP OAM on MPLS-TP network (at LSP level) (1) Physical level OAM (MAY be of several kinds) Open Points: o Interworking between MPLS-TP network OAM ((2), (3)) and IP/MPLS network OAM ((4), (5)) is still to be cleared/defined; it could imply fault indication, alarm suppression, etc. Martinotti, et al. Expires September 6, 2009 [Page 15] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 o Interaction between IP/MPLS and MPLS-TP CPs is still to be cleared/defined o MPLS-TP edge nodes provides Forwarding Adjacency to the IP/MPLS network; this handling is left for further study. 7.1.3.2. IP/MPLS requires PHP from MPLS-TP Note: the following scenario is NOT recommended. 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 \| +-------------------+ ^ \_________________/ PW emulation Nodes: +++++ +++++ + 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 10 Martinotti, et al. Expires September 6, 2009 [Page 16] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 The Node 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 As Node 8 of client IP/MPLS network requires PHP, Node 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 Node 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 (direction from 1 to 8 shown): |--------+----------------------CLI----------------+--------| |--SRV--| |---------------------PW------(PHP)->---| |--SRV--| |------+-------+------LSP-----| |--SRV--| |-SRV-| |-SRV-| |--PW---------| |-LSP--+------| |-ETH-| |-ETH-| |-ETY-| |-ETY-| OAM: (4) >-------------?---------------?-------< PW (3) >-----------< PW (2) >-----------< LSP (1) >---< >...< >...< >-----< PHY Nodes: +++++ +++++ +++++ +++++ +++++ +++++ +++++ +++++ + 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 11 Several levels of OAM are possible, a subset of them is shown in the previous figure, however these are not comprehensive, any subset of them MAY be configured in a network. A brief description of the different levels is provided: Martinotti, et al. Expires September 6, 2009 [Page 17] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 (4) Edge-to-Edge MPLS OAM on IP/MPLS network (at PW level) (3) Edge-to-Edge MPLS-TP OAM on MPLS-TP network (at PW level) (2) Edge-to-Edge MPLS-TP OAM on MPLS-TP network (at LSP level) (1) Physical level OAM (MAY be of several kinds) Open Issues: o As in the IP/MPLS network the LSP, which is tunneled over MPLS-TP network, is terminated on a Node requiring PHP (Node 8), IP/MPLS OAM cannot be used at LSP level, so monitoring can be performed at PW level. o Interworking on Node 6 between MPLS-TP OAM and IP/MPLS OAM (at PW level) MAY be performed in egress direction, but its details are out of scope of this document. o Interworking between MPLS-TP OAM and IP/MPLS OAM (at PW level) SHOULD NOT be performed in ingress direction, due to independence of layers. Open Points: o Interworking between MPLS-TP network OAM ((2), (3)) and IP/MPLS network OAM (4) is still to be cleared/defined o Interaction between IP/MPLS and MPLS-TP CPs is still to be cleared/defined o MPLS-TP edge nodes provides Forwarding Adjacency to the IP/MPLS network; this handling is left for further study. 7.2. Network Partitioning In the rest of this Section the following assumptions apply: o Customer network is carried partly over IP/MPLS subnetwork (e.g. via PW encapsulation) and partly over MPLS-TP subnetwork. o IP/MPLS network is deployed over Ethernet (at least on interfaces interconnecting to the MPLS-TP subnetwork) o MPLS-TP subnetwork is deployed over Ethernet, however other server layers are possible (not shown in this document) For the purposes of this Section, MPLS-TP subnetwork is deployed Martinotti, et al. Expires September 6, 2009 [Page 18] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 between a CE and an IP/MPLS subnetwork. Other kinds 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 Node Main features to be taken into account: o MultiSegment Pseudowire o LSP Stitching o Network Interworking o End-to-End OAM support o Interaction between DP of IP/MPLS and DP of MPLS-TP o Interaction between CP of IP/MPLS and CP of MPLS-TP o Interaction between MP of IP/MPLS and MP of MPLS-TP o No need of PHP handling by MPLS-TP node 7.2.1.1. Multisegment Pseudowire The following figure illustrates the functional interworking among the networks: Martinotti, et al. Expires September 6, 2009 [Page 19] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 Networks: Customer Network +---+ - - - - - - - - - - - - - - - - - +---+ | _______________ _______________ | |/ IP/MPLS Net. \ / MPLS-TP Net. \| +-----------------+-----------------+ ^ \_______________/ \_______________/ PW emulation PWs: |-------------MS-PW-------------| |---------------|---------------| ^ ^ PW segments Nodes: +++++ +++++ + 1 +----+- - - - - - - - - - - - - - - -+----+ 7 + +++++ | | +++++ CE +++++ +++++ +++++ +++++ +++++ CE + 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 + +++++ +++++ +++++ +++++ +++++ LER LSR LER LSR LER T-PE S-PE T-PE Border Node - Multisegment Pseudowire - Networks and PWs view Figure 12 The following figure illustrates the stacking relationship among the technology layers and OAM relationship among the networks: Martinotti, et al. Expires September 6, 2009 [Page 20] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 Layers: |--------+--------------CLI--------------+--------| |--SRV--| |---------PW---+--------------| |--SRV--| |-----LSP-----| |-----LSP-----| |-ETH-| |-ETH-| |-ETH-| |-ETH-| |-ETY-| |-ETY-| |-ETY-| |-ETY-| OAM: (3) >-------------O-------------< MS-PW (2) >-----------< >-----------< LSP (1) >--< >...< >---< >...< >...< >--< PHY Nodes: +++++ +++++ +++++ +++++ +++++ +++++ +++++ + 1 +--+ 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 +--+ 7 + +++++ +++++ +++++ +++++ +++++ +++++ +++++ CE LER LSR LER LSR LER CE Border Node - Multisegment Pseudowire - Layers and OAM view Figure 13 Several levels of OAM are possible, a subset of them is shown in the previous figure, however these are not comprehensive, any subset of them MAY be configured in a network. A brief description of the different levels is provided: (3) Edge-to-Edge MPLS/MPLS-TP OAM on partitioned network (at PW level) (2) Edge-to-Edge MPLS/MPLS-TP OAM on partitioned network (at LSP level) (1) Physical level OAM (MAY be of several kind) Open Points: o Interworking between LSP OAM (2) and MS-PW OAM (3) is still to be cleared/defined o Edge-to-Edge MS-PW OAM (3) must be configured on different subnetworks Martinotti, et al. Expires September 6, 2009 [Page 21] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 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-------------| Nodes: +++++ +++++ + 1 +----+- - - - - - - - - - - - - - - -+----+ 9 + +++++ | | +++++ CE +++++ +++++ +++++ +++++ +++++ CE + 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 + +++++ +++++ +++++ +++++ +++++ LER LSR LER LSR LER PE PE Border Node - LSP stitching - Networks and PWs view Figure 14 The following figure illustrates the stacking relationship among the technology layers and OAM relationship among the networks: Martinotti, et al. Expires September 6, 2009 [Page 22] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 Layers: |--------+--------------CLI--------------+--------| |--SRV--| |--------------PW-------------| |--SRV--| |-------------<->-LSP---------| |-ETH-| |-ETH-| |-ETH-| |-ETH-| |-ETY-| |-ETY-| |-ETY-| |-ETY-| OAM: (4) >---------------------------< PW (3) >-------------O-------------< LSP (2) >-----------< >-----------< TCM (1) >--< >...< >---< >...< >...< >--< PHY Nodes: +++++ +++++ +++++ +++++ +++++ +++++ +++++ + 1 +--+ 2 +...+ 3 +---+ 4 +...+ 5 +...+ 6 +--+ 7 + +++++ +++++ +++++ +++++ +++++ +++++ +++++ CE LER LSR LER LSR LER CE Border Node - LSP stitching - Layers and OAM view Figure 15 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. Several levels of OAM are possible, a subset of them is shown in the previous figure, however these are not comprehensive, any subset of them MAY be configured in a network. A brief description of the different levels is provided: (4) Edge-to-Edge MPLS/MPLS-TP OAM on partitioned network (at PW level) (3) Edge-to-Edge MPLS/MPLS-TP OAM on partitioned network (at LSP level) (2) Edge-to-Edge MPLS/MPLS-TP OAM on partitioned network (at TCM level) (1) Physical level OAM (MAY be of several kind) Open Points: o Edge-to-Edge LSP OAM (3) must be configured on different subnetworks Martinotti, et al. Expires September 6, 2009 [Page 23] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 o Edge-to-Edge PW OAM (4) must be configured on different subnetworks o Interworking between TCM OAM (2) and LSP OAM (3) is still to be cleared/defined o Interaction between IP/MPLS and MPLS-TP CPs 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 between DP of IP/MPLS and DP of MPLS-TP o Interaction between CP of IP/MPLS and CP of MPLS-TP o No interaction between MP of IP/MPLS and MP of MPLS-TP o Possible PHP handling of client MPLS Layer 7.2.2.1. Multisegment Pseudowire The following figure illustrates the functional interworking among the networks: Martinotti, et al. Expires September 6, 2009 [Page 24] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 Networks: Customer Network +---+ - - - - - - - - - - - - - - - - - -+---+ | ___________ ______________ | |/IP/MPLS N. \ / MPLS-TP N. \| +-------------+-----+----------------+ ^ \___________/ \______________/ PW emulation PWs: |------------MS-PW--------------| |-----------|-----|-------------| ^ ^ ^ PW segments Nodes: +++++ +++++ + 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 16 The following figure illustrates the stacking relationship among the technology layers and OAM relationship among the networks: Martinotti, et al. Expires September 6, 2009 [Page 25] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 Layers: |--------+-------------CLI---------------+--------| |--SRV--| |--------+----PW---+----------| |--SRV--| |--LSP--| |--LSP--| |---LSP---| |- ETH -| |--ETH--| |- -ETH- -| |- ETY -| |--ETY--| |- -ETY- -| OAM: (3) >-------O---------O---------< MS-PW (2) >-----< >-----< >-------< LSP (1) >--< >.....< >-----< >.......< >--< PHY Nodes: +++++ +++++ +++++ +++++ +++++ +++++ + 1 +--+ 2 +.....+ 3 +-----+ 4 +.......+ 5 +--+ 6 + +++++ +++++ +++++ +++++ +++++ +++++ CE LER LER LER LER CE Border Link - Multisegment Pseudowire - Layers and OAM view Figure 17 Several levels of OAM are possible, a subset of them is shown in the previous figure, however these are not comprehensive, any subset of them MAY be configured in a network. A brief description of the different levels is provided: (3) Edge-to-Edge MPLS/MPLS-TP OAM on partitioned network (at PW level) (2) Edge-to-Edge MPLS/MPLS-TP OAM on partitioned network (at LSP level) (1) Physical level OAM (MAY be of several kinds) Open Points: o Interworking between LSP OAM (2) and MS-PW OAM (3) is still to be cleared/defined o LSP between Node 3 and 4 could be avoided, however in this case PW over Ethernet should be specified. o Edge-to-Edge MS-PW OAM (3) must be configured on different subnetworks Martinotti, et al. Expires September 6, 2009 [Page 26] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 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--------------| Nodes: +++++ +++++ + 1 +----+- - - - - - - - - - - - - - - -+----+ 6 + +++++ | | +++++ CE +++++ +++++ +++++ +++++ CE + 2 +.....+ 3 +-----+ 4 +.......+ 5 + +++++ +++++ +++++ +++++ LER LER LER LER PE PE Border Link - LSP stitching - Networks view Figure 18 The following figure illustrates the stacking relationship among the technology layers and OAM relationship among the networks: Martinotti, et al. Expires September 6, 2009 [Page 27] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 Layers: |--------+-------------CLI---------------+--------| |--SRV--| |-------------PW--------------| |--SRV--| |-------<->--LSP--<->---------| |- ETH -| |--ETH--| |- -ETH- -| |- ETY -| |--ETY--| |- -ETY- -| OAM: (4) >---------------------------< SS-PW (3) >-------O---------O---------< LSP (2) >-----< >-----< >-------< TCM (1) >--< >.....< >-----< >.......< >--< PHY Nodes: +++++ +++++ +++++ +++++ +++++ +++++ + 1 +--+ 2 +.....+ 3 +-----+ 4 +.......+ 5 +--+ 6 + +++++ +++++ +++++ +++++ +++++ +++++ CE LER LER LER LER CE Border Link - LSP stitching - Layers and OAM view Figure 19 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. Several levels of OAM are possible, a subset of them is shown in the previous figure, however these are not comprehensive, any subset of them MAY be configured in a network. A brief description of the different levels is provided: (4) Edge-to-Edge MPLS/MPLS-TP OAM on partitioned network (at PW level) (3) Edge-to-Edge MPLS/MPLS-TP OAM on partitioned network (at LSP level) (2) Edge-to-Edge MPLS/MPLS-TP OAM on partitioned network (at TCM level) (1) Physical level OAM (MAY be of several kinds) Open Points: o Edge-to-Edge LSP OAM (3) must be configured on different subnetworks o Edge-to-Edge PW OAM (4) must be configured on different subnetworks Martinotti, et al. Expires September 6, 2009 [Page 28] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 o Interworking between TCM OAM (2) and LSP OAM (3) is still to be cleared/defined o Interaction between IP/MPLS and MPLS-TP CPs 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 still appear, the reader is invited to contribute to their resolution. The following scenarios are recommended: Network Layering Ethernet encapsulation over MPLS-TP Transparent transport of IP/MPLS Network Partitioning Border Link, using Multisegment Pseudowire 9. Acknowledgements The authors gratefully acknowledge the input of Attila Takacs. 10. IANA Considerations This memo includes no request to IANA. 11. Security Considerations This document does not introduce any additional security aspects beyond those applicable to PWE3 and MPLS. 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. Martinotti, et al. Expires September 6, 2009 [Page 29] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 12.2. Informative References [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol Label Switching Architecture", RFC 3031, January 2001. [draft jenkins] Niven-Jenkins, B., Brungard, D., and M. Betts, "MPLS-TP Requirements", ID draft-jenkins-mpls-mpls-tp-requirements-00, July 2008. [draft mpls-tp framework] Bocci, M., Bryant, S., and L. Levrau, "A Framework for MPLS in Transport Networks", ID draft-ietf-mpls-tp-framework-00, November 2008. [draft vigoureux] Vigoureux, M., "Requirements for OAM in MPLS Transport Networks", ID draft-vigoureux-mpls-tp-oam-requirements-00, June 2008. [ITU-T G.805] "Generic functional architecture of transport networks", ID ITU-T G.805, March 2000. 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 Martinotti, et al. Expires September 6, 2009 [Page 30] Internet-Draft draft-martinotti-mpls-tp-interworking-01 March 2009 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 Alessandro D'Alessandro Telecom Italia Via Reiss Romoli, 274 Torino 10148 Italy Email: alessandro.dalessandro@telecomitalia.it Alessandro Capello Telecom Italia Via Reiss Romoli, 274 Torino 10148 Italy Email: alessandro.capello@telecomitalia.it Martinotti, et al. Expires September 6, 2009 [Page 31]