1 TM8106 Optical Networking Multi-Protocol Label Switching-Transport Profile (MPLS-TP) By Ameen Chilwan Syllabus: [1] MPLS Transport Profile (MPLS-TP):

1

TM8106Optical Networking

Multi-Protocol Label Switching-Transport Profile

(MPLS-TP)

By

Ameen Chilwan

Syllabus:

[1] MPLS Transport Profile (MPLS-TP): A Set of Enhancements to the Rich MPLS Toolkit, Juniper Networks, Whitepaper, 2011.

[2] Dieter Beller, Rolf Sperber, MPLS-TP – The New Technology for Packet Transport Networks, 2nd DFN Forum, 2009.

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Outline

• Transport Networks• MPLS-TP Basics• Standardization History• MPLS-TP Components

OAM Control Plane Resiliency

• Synchronization• Physical Infrastructure Support• Deployment Options• Misconceptions about MPLS-TP• Conclusion

27.09.2012TM8106 Optical Networking - MPLS-TP

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Transport Networks• Goal of transport network

• Requirements


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Packet-based Transport Network

• MPLS has been serving as one for almost a decade

Connection-oriented and Packet-based

Designed to carry L3 IP Traffic

Establishes IP traffic paths

Associates these paths with arbitrarily assigned labels

• GMPLS extends MPLS

Label switching for

• TDM (SONET/SDH)

• Wavelength (λ)

• Spatial switching (incoming ports to outgoing ports)27.09.2012TM8106 Optical Networking - MPLS-TP

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MPLS-TP Emergence

• Lacks some features of SDH-like networks

Operation, Admin and Management (OAM)

Resiliency

Scalable operations

High availability

Performance monitoring

Multi-domain support

• IETF and ITU-T joined forces to enhance MPLS

MPLS-TP


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MPLS-TP Background

• Drivers for MPLS-TP

Rise in demand for service sophistication

• Bandwidth-hungry services

Pressure to reduce operational cost (OPEX)

Maximize the value per bit

• Lead to a technology that is almost SDH-like

Carrier-grade

Packet-switched

With OAM features


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MPLS-TP Overview• Takes a subset of MPLS/GMPLS• Enhance with some functionalities

Network Management (e.g. FCAPS) Dynamic provisioning of transport paths via control plane Provide restoration functions E2E path provisioning across networks/domains

• Characteristics Connection oriented Client and physical layer agnostic OAM similar to SDH-like networks Protection schemes Network provisioning via centralized NMS GMPLS Control plane applicable


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Standardization History

• ITU-T will define requirements

• IETF will work on protocol extensions


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MPLS-TP Components


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Operation, Admin and Management• Dedicated OAM packet

interspersed into the associated user traffic flows Created and processed by maintenance end-points Intermediate points can also process them & collect data

• OAM Tools


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OAM Functions and Tools

• Functions

Fault Detection (e.g. connectivity check)

Fault Localization (e.g. loopback, lock)

Performance Monitoring (e.g. delay, loss)

• Tools (Existing MPLS tools extended)

Bidirectional Forwarding Detection (BFD)

LSP Ping

LSP Trace


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OAM Enhancements


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Associated Channel (ACh)• MPLS-TP shall work without IP functionality

MPLS uses Ach for framing, forwarding and encapsulation

Enhanced by GACh and GACh Label (GAL)

Support in-band control channels

• GACh

Ensure congruency between OAM packets and data path

Indicates tagged packet must be processed by special

function

Not suitable for static provisioning

• Because negotiated when pseudowire was setup

• Solved using GAL (reserved value of 13)

– Enables easy extraction at end- and mid-point nodes


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Control Plane (Static and Dynamic)• Responsible for setup of LSP• MPLS has mature and dynamic control plane

OSPF-TE, IS-IS-TE, RSVP-TE and BGP

• Current transport networks have static control plane using NMS

• MPLS-TP Can have both static or dynamic Dynamic has advantages like:

• Scaling• Advanced protection functions (e.g. LSP tail-end protection)• Restoration

Distributed control plane• Signaling, routing and TE

Decoupled from data plane27.09.2012TM8106 Optical Networking - MPLS-TP

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MPLS-TP Control Plane (contd…)


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Resiliency

• Mechanisms in MPLS

LSP fast reroute

Pseudowire redundancy

Path protection

• Enhancements in MPLS-TP

OAM-triggered protection

Optimizing protection in ring topologies

• Circuit networks are interconnected rings

• Fast reroute works but inefficient

• Wrapping and steering implemented in MPLS-TP27.09.2012TM8106 Optical Networking - MPLS-TP

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Synchronization

• Approaches

An overlay synchronization network

• Requires parallel network

Distributed reference clock

• Reference clock at least at the edges

Forwarding of clock information across packet domain

• Synchronization protocol


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Synchronization (contd..)• Packet based clock

recover solution Adaptive Timing

• Encapsulated and de-capsulated at packet edge nodes between TDM and packet domain

Differential Timing • Both edge nodes

performing inter-working have access to reference clock


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Physical Infrastructure Support• MPLS-TP over SDH/SONET, PDH and OTN

ITU-T defines Generic Framing Procedure (GFP)

• Encapsulate variable length payload of various client signal

• Contains User Payload Identifier (UPI)

• MPLS-TP uses same UPI point code as MPLS

• OTN includes WDM network layer for transport of a variety of

OTN client signals

• SONET/SDH uses virtual concatenation to form transmission

pipelines with larger capacities

• MPLS-TP over Gigabit Ethernet

• Two-octet long Ether Type field in Ethernet II Indicates which

protocol is encapsulated in payload27.09.2012TM8106 Optical Networking - MPLS-TP

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Deployment Options

• Access and aggregation network

Major migration from circuit to packet happening nowadays

• OAM enhancements will allow more visibility into Core


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Misconceptions about MPLS-TP

• MPLS-TP is a new technology, not part of MPLS It is a subset of MPLS with some enhancements

• Extensions in MPLS-TP are not applicable in MPLS Actually meant to apply in MPLS to make it broadly applicable

• MPLS-TP requires substantial changes in MPLS Design goal of MPLS-TP is to keep MPLS architecture

• MPLS-TP require static provisioning Supports both static and dynamic control planes

• Requires forklift hardware upgrades Might be true for some vendors, but not always, not in Juniper

at least


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Conclusion• MPLS-TP is

Subset of MPLS/GMPLS Enhancements esp. OAM

• Fault management• Performance monitoring

E2E integration with existing and next generation MPLS networks

• MPLS-TP intended to Tie together

• service routing • transport platforms

Advantages of tying together• Consistent operations and OAM functions across networks• Seamless interworking with IP/MPLS networks• Scalability due to multiplexing capability• Supports huge variety of services encapsulated into pseudowires


23 27.09.2012TM8106 Optical Networking - MPLS-TP

Documents

1 TM8106 Optical Networking Multi-Protocol Label Switching-Transport Profile (MPLS-TP) By Ameen Chilwan Syllabus: [1] MPLS Transport Profile (MPLS-TP):