04/18/23 draft-bocci-bryant-ms-pw-architecture-00.txt

An Architecture for Multi-Segment Pseudo Wire Emulation Edge-to-Edge

draft-bocci-bryant-pwe3-ms-pw-architecture-00.txt

Matthew Bocci (Alcatel)

Stewart Bryant (Cisco)

04/18/23 draft-bocci-bryant-ms-pw-architecture-00.txt

Objectives & Key Issues

• Objectives– Document the main network scenarios for MS-PW applicability– Define architectural framework:

• Specify which protocol functions that we need

• Key Issues– Applicability of MS-PWE3 vs. L2VPN– Protocol Layering Model– Network reference Models– PE Reference Model– Protocol Stack Reference Model

• Gaps

04/18/23 draft-bocci-bryant-ms-pw-architecture-00.txt

Applicability & Domain of MS PWE3• A MS-PW is a single PW that for technical or administrative reasons

is segmented into a number of concatenated hops.

• From perspective of U-PE, MS-PW is indistinguishable from SS-PW.

• MS-PW abstracts complex PWs from the construction of a L2VPN

• PWE3 does not do: PSN tunnel setup, PSN tunnel maintenance and routing, U-PE discovery

• PWE3 does do: S-PE selection to reach a U-PE

U-PE U-PE

U-PE U-PE

S-PE S-PE

MS-PW

04/18/23 draft-bocci-bryant-ms-pw-architecture-00.txt

Protocol Layering Model

• Same as RFC 3985 except:– Pseudo-wires may be considered to be a separate layer

to the PSN tunnel.

– Independent of the PSN tunnel routing, operations, signalling and maintenance.

– Design of PW domains should not imply the underlying PSN routing domains are the same.

• MS-PW will reuse protocols of the PSN

04/18/23 draft-bocci-bryant-ms-pw-architecture-00.txt

Network Reference Models

Native |<-----------Pseudo Wire----------->| Native Service | | Service (AC) | |<-PSN1-->| |<-PSN2-->| | (AC) | V V V V V V | | +----+ +-----+ +----+ +----+ | |UPE1|=========|SPE1 |=========|UPE2| | +----+ | |-------|....PW.Seg't1........PW Seg't3.....|----------| | | CE1| | | | | | | | | |CE2 | | |-------|....PW.Seg't2.......|PW Seg't4.....|----------| | +----+ | | |=========| |=========| | | +----+ ^ +----+ +-----+ +----+ ^ | Provider Edge 1 ^ Provider Edge 2 | | | | | | | | PW switching point | | | |<------------------- Emulated Service ------------------>|

• Intra-provider & inter-provider

04/18/23 draft-bocci-bryant-ms-pw-architecture-00.txt

PE Reference Model

• Pre-processing in U-PEs as RFC 3985• Processing in S-PEs:

– No native service processing

– Egress PW label mapping based on ingress label

– Static or dynamic config

– 1:1 mapping between ingress and egress PW +------------------------------------------+ | S-PE Device | +------------------------------------------+ Ingress | | | | Egress PW instance | Single | | Single | PW Instance <==========>X PW Instance + Forwarder + PW Instance X<==========> | | | | +------------------------------------------+

04/18/23 draft-bocci-bryant-ms-pw-architecture-00.txt

Protocol Stack Reference Model

+----------------+ +----------------+

|Emulated Service| |Emulated Service| |(e.g., TDM, ATM)|<======= Emulated Service =======>|(e.g., TDM, ATM)| +----------------+ +----------------+ | Payload | | Payload | | Encapsulation |<== Multi-segment Pseudo Wire ===>| Encapsulation | +----------------+ +--------+ +----------------+ |PW Demultiplexer|<PW Segment>|PW Demux|<PW Segment>|PW Demultiplexer| +----------------+ +--------+ +----------------+ | PSN Tunnel, |<PSN Tunnel>| PSN |<PSN Tunnel>| PSN Tunnel, | | PSN & Physical | |Physical| | PSN & Physical | | Layers | | Layers | | Layers | +-------+--------+ +--------+ +----------------+ | .......... | .......... | | / \ | / \ | +==========/ PSN \===/ PSN \==========+ \ domain 1 / \ domain 2 / \__________/ \__________/ `````````` ``````````

Remove PSN1 demuxAdd PSN2 demuxApply policies

04/18/23 draft-bocci-bryant-ms-pw-architecture-00.txt

Other Issues

• Control Plane:– Can be static or dynamic

• Gaps in current version of the draft:– Maintenance reference model– Security issues

04/18/23 draft-bocci-bryant-ms-pw-architecture-00.txt

Conclusions

• Architecture is fundamental to the solution– Would like to achieve consensus as early as

possible

• Please provide comments and text to improve the draft!