MS-PWs: A Small Step for Pseudowires, A Giant Leap for Metro Convergence? Jeff Sugimoto - Nortel [e-mail]

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MS-PWs A Small Step for Pseudowires, A Giant
Leap for Metro Convergence? Jeff Sugimoto -
Nortel sugimoto_at_nortel.com
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Metro B
Metro A
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Network Evolution
Service Edge
MPLS WAN
MSE

• Network simplification streamlining
• Consistent Network for New and Legacy Services
• Collapse Operational Groups
• Standardize on Ethernet Interfaces, including the
  MSE
• Dynamically Provision Resize Transport Tunnels,
  Services
• Transport Efficiency Gains
• Peel out data services from fixed size TDM
  circuits

Driving Packet Convergence in the Metro
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Why PWs for Packet Convergence?

• Enable Service, Network consolidation
• Multi-service
• Transport Agnostic
• Commonality with the WAN
• Feature Rich - Inherits the Properties of the
  MPLS Tunnel Layer
• Dynamically Provision Resize Transport Tunnels,
  Services
• OAM (LSP-PING, VCCV, Status TLV)
• Resiliency (FRR, Global Repair, IP)
• Traffic Engineering
• Service Rich VPWS, VPLS
• Safe technology direction
• Standards in Place
• Broad Industry Adoption

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Typical Deployment Models
ATM Frame Ethernet
MPLS Metro
L3 VPN
MSE
Inter/intra provider bound
ATM Frame Ethernet
MPLS WAN

• Local backhaul to an MSE service
• Psuedowire access to L2 VPN, L3 VPN, Internet
  access

• 2. Local L2 transport
• Pseudowires/VPLS originates and terminates in the
  MPLS access network

• 3. End to End Layer 2 transport
• Pseudowires provides transport end to end across
  the network

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Deployment models Network view
Metro-Access Interconnection Use Case
Metro A
Core
Metro B
Inter-Provider Use Case
Provider A
Provider B
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Why not just re-use existing PW/MPLS Technology?
Metro A
WAN
Metro B
MPLS Network 10,000s devices

• Challenges
• PWE3 Control Scaling
• PSN Scaling
• PSN Interoperability
• Authentication/Security
• Traffic Engineering QoS
• Discovery/Provisioning
• Increased OPEX, CAPEX?

Metro-Access Interconnection Use Case
?
Provider A
Provider B
Inter-Provider Use Case
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Motivations for Multi-Segment PWs
Metro-Access Interconnection Use Case
WAN Core
Metro A
Metro B
MS-PWs Enable

• Limit Mesh to Domain
• Fewer PSN Tunnels
• Manageable Control
• Different PSN Technologies
• Dry-Martini like MAN
• PSN Conversion at S-PEs
• Authentication at Boundary
• Low Cost U-PEs

Ultimate-PEs (U-PEs)
Switching PEs (S-PE)
U-PEs
Provider A
Provider B
Inter-Provider Use Case
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MS-PW Standardization ProgressWorking Group
Drafts - IETF PWE3

• MS-PW Requirements - draft-ietf-pwe3-ms-pw-require
  ments
• Contributions from a number of Service Providers
• Manual Configuration of MS-PWs draft-ietf-pwe3-seg
  mented-pw
• Manual stitching of PW Segments in the S-PEs
• Interworking different PW Segments e.g. static
  to dynamic, MPLS to L2TP
• Dynamic Placement of MS-PW - draft-ietf-pwe3-dynam
  ic-ms-pw-00.txt draft-balus-bocci-martini-dyn-ms-
  pwe3-00.txt just submitted as WG document
• No S-PE provisioning, automatic selection of the
  next PW Segment
• 11 Protection, Re-routing around the point of
  failure

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Why Extend Existing PW Procedures? Key
Principles draft-balus-bocci-martini-dyn-ms-pwe3

• Operational Consistency, Familiarity with SS-PWs
• Same Service Management, Provisioning Models
• OSS Touches at only U-PEs
• Generalized Solution (SS/MS) as a Super Set of
  Existing Procedures
• Existing PW Implementations, Deployments based on
  LDP Signaling
• Re-use Signaling Procedures, Addressing
• Minimal Changes (i.e. new addressing) to satisfy
  the MS-PW Requirements
• Address Customer Use Cases
• Easily applicable to existing LDP-VPLS
  Implementations

Small Addition to Existing PWs minimizes the
Implementation Effort. Enables Fast Track
Technology Expansion.
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Building Blocks from Single to Multi-Segment PWs
LDP

• PWs Setup and Maintenance
• Define Multi-service Transport over PSN
• Signaling L2 FEC using LDP
• draft-ietf-pwe3-control-protocol
• Scope is one network domain (WAN)

PE2
PE1
SS-PW
P
VF
VF
L2FEC
VF Virtual Forwarder
SP Switching Point
MS-PW
LDP
LDP

• Multi-Segment PWs
• Segmentation of Control and Data Plane
• Adds Service (to Tunnel) Label Switching
• Build a Virtual Circuit across Multiple Domains
• Enabler for different PSN technologies

S-PE
U-PE1
U-PE2
SP
VF
VF
L2FEC
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Segmented PW Model - draft-ietf-pwe3-segmented-pw

• Manual Configuration
• PW X maps to PW Y
• Service Label Switching

SS-PW
SS-PW
S-PE
T-PE 1
T-PE 2
SP
VFx
VFy
LDP
LDP
PW X
PW Y
Useful for Interworking between Static PW,
E-LDP-based (FEC 128, 129), different PSN types
e.g. MPLS, L2TP
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MS-PW Information Model - draft-ietf-pwe3-dynamic-
ms-pw-00.txt Unique Identification of PW Endpoint
SS-PW
SS-PW
S-PE
T-PE 1
T-PE 2
SP
VFx
VFy
LDP
LDP

• No Provisioning Required
• Automatic Selection of the next SS-PW
• Service Label Switching

Identical Service Management for both SS/MS-PWs
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Generalized Signaling Procedures (SS/MS-PWs)
draft-ietf-pwe3-dynamic-ms-pw-00.txt
TAII AS-IP2-200
2. Before sending LM check TAII against
routing table. No full match on local i/f.
Longest match gt NSH (next signaling hop)
6. On LM receipt check TAII against routing
table. Full match on local i/f implies T-PE.
S-PE
T-PE2
T-PE1
P
P
SP
VF
VF
LDP1
LDP2
Same Service Provisioning for SS/MS-PWs, in-line
w/ existing PW Technology
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MS-PWs Enable Technology Options for Individual
PSNs
S-PE
S-PE
U-PEs
PW over PBT
PW over MPLS (RSVP-TE/LDP)
PW over PBT
U-PEs

• MS-PWs enable convergence of the service layer
  across the network
• Architecture separates service layer from tunnel
  layer
• MS-PWs are transparent to tunnel layer
  functionality
• Trunks between x-PEs may be setup using LDP,
  RSVP-TE, GMPLS
• Provider Backbone Transport (PBT)
  Ethernet-based Trunks
• Ethernet instantiation of Dry-Martini - see
  draft-fedyk-gmpls-ethernet-ivl-00.txt

• Revenue Generating Service (PWs) decoupled from
  PSN Technology
• PSN choices should be driven by business model,
  cost target, use case

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MS-PW Application Inter-Provider
Multi-segment PWE3 End-to-end
U-PE

• Dominant Attribute
• Operational Simplicity
• End to End Provisioning

Provider A
MD-5 Authentication
S-PE
U-PE
S-PE
Inter-provider options
S-PE

• Dominant Attribute
• Control
• Mask addressing scheme

Provider B
S-PE
S-PE
U-PE
Multi-segment PWE3
SS-PW
Interworking, Static Provisioning
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MS-PW Application (H)VPLS
MTU-s
MTU-s
Metro
S-PE3
Provider B

• Enable Distributed VPLS
• Complements HVPLS technology
• VSI on S-PE only if 2 PWs are required
• MAC Learning only on T-PE
• Inter-Provider VPLS
• Transparent to existing VPLS Provisioning, A/D
  Procedures

S-PE1
PE-rs
Core Provider A
S-PE2
MTU-s
S-PE1
Metro
PE-rs
PE-rs
T-PE function
S-PE function
S-PE4
Virtual Switch Instance
MS-PWs between VSIs
MTU-s
SS-PWs between VSIs
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Summary

• The Move to Packet based Infrastructure underway
  in the Metro
• one network to handle new and legacy services
• Pseudowires provide an Ideal Framework
• but new end-to-end MPLS Paradigms provide New
  Challenges
• Multi-Segment Pseudowires address SS-PW
  Challenges
• Scalability, PSN Interoperability, Low Cost
  Edge (MTU/DSLAM)

MS-PW Provides enables Service Convergence while
allowing cost effective technology choices for
Individual PSN domains
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MPLS WAN
Metro B
Metro A