building a highly adaptive resilient and scalable mpls1352

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2006 Verizon. All Rights Reserved. PT00000. 00/00/06

Building a Highly Adaptive, Resilient,

and Scalable MPLS Backbone

Building a Highly Adaptive, Resilient,

and Scalable MPLS Backbone

Ning So, Verizon Business

Hao-Hsin Huang, WANDL, Inc.

Feb. 9, 2007MPLS World Congress 2007Paris, France


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AgendaAgenda

About Verizon Business and WANDL

Verizon Business MPLS core network

MPLS TE Fast Reroute (FRR) design on VzB MPLS core

Design challenges and solutions

Solving LSP meshing scalability Q&A


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Verizon BusinessVerizon BusinessVerizon Business is the premier communications solutions

provider for global businesses, government agencies, andeducational institutions.

Data and IP services

Security

IT solutions

Managed networks

Premises equipment

Contact centers

ConferencingVoice


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WANDLWANDLWANDL is the leading supplier of software solutions for advanced

network planning, management, design, and optimization

20 years expertise in software development for network optimization,planning, design, OSS/automation

Work with Cisco, Juniper, Tellabs, Alcatel, Nortel, Lucent, Huawei, etc.

Manage technologies such as IP, MPLS, VoIP, transport(SONET/SDH), FR/ATM ,TDM

Customers include carriers, ISPs, telcos, PTTs, service providers,enterprise, and government organizations


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MPLS Core Network OverviewMPLS Core Network Overview

Verizon Business Private MPLS Core Network

U.S.-based

Backbone trunks are OC48 and OC192 packet-over-SONET

Provide Layer 2 (MPLS-TE) transport services for Verizon Businessprivate data networks including IP, Ethernet, and Frame Relay

networks


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Drawing of the MPLS Core NetworkDrawing of the MPLS Core Network


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Key Objectives of the NetworkKey Objectives of the Network

Network Capacity

Provide sufficient backbone capacity to carry traffic from all feedernetworks

Network Resiliency

100% traffic re-route during single hardware and/or transmission facility

failure

Network Performance

Provide the minimal latency routes available between any two network

elements Network Efficiency

Best practices in network architecture and traffic engineering techniques to

optimize network routing and resource usage


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Why Implement MPLS TE FRR?Why Implement MPLS TE FRR?

Underlying transmission facilities supporting the MPLS core network aregradually shifting from a 1+1 SONET ring-based infrastructure to 1+0linear-based infrastructure.

Transmission equipment moving from conventional DWDM to Ultra LongHaul (ULH). ULH favors linear over ring infrastructures.

ULH has fewer optical regions compared with conventional systems, resulting in

a less efficient ring design (larger rings) and no impact on linear designULH has a much higher availability rate, reducing the need for the ring system for

transmission facility maintenance and repair work

The core network with linear transmission facility relies more on the Layer

2 reroute for service restoration.

MPLS TE FRR is the only proven technology that provides servicerestoration at a speed comparable to ring-based restoration.


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FRR Implementation Design ChallengesFRR Implementation Design Challenges

FRR design can be highly complicated with implementation andmanagement presenting bigger challenges to service providers.

FRR design challenges

1. Bundled FRR design for ease of implementation and management

2. FRR bandwidth and pre-emption design

3. FRR design with built-in facility failures knowledge base

4. Do not re-route LSP on a FRR-enabled network environment


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FRR Design Challenge #1FRR Design Challenge #1

Description

When Juniper FRR is engineered and signaled on a per LSPbasis, service providers lose the control of FRR route selection

Design and management of individual FRR quickly becomes tootime consuming for service providers with a large MPLS core

network (such as the Verizon Business MPLS Core network).

Solution

Utilize the node/link protection scheme


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Challenge #1 Solution Illustration NLP Discovery and Design ParametersChallenge #1 Solution Illustration NLP Discovery and Design Parameters

NLP flag on LSP

Auto FRR designparameters

Primary tunnel path in yellowNLP bypass tunnel in green


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Challenge #1 Solution Bypass Tunnel andIts Protected Primary Tunnel PathsChallenge #1 Solution Bypass Tunnel andIts Protected Primary Tunnel Paths

Bypass tunnel path Protected path

All tunnels being protectedby this bypass tunnel


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Description

How to set up the bypass tunnel bandwidth and preemption?

Problems occur if bypass tunnel bandwidth is set up accordingto the primary LSP bandwidth Additional bandwidth on the backbone has to be reserved for FRR, causing

inefficient use of valuable network resources

FRR bandwidth and preemption design quickly becomes too complicatedwhen multiple FRR paths are set up to account for multiple network failures

Multiple network element failure can cause domino effect on FRR reroutedue to preemption which magnifies the problem and causes networkinstability

Service provider loses performance predictability due to the massiveamount of combinations and permutations of the re-route scenarios


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Solution

Set bypass tunnel bandwidth to zero, effectively turningoff the preemption

All traffic on the FRR route share the pain during theoutages

Rely on the LSP re-signal to restore the LSP primaryroute, based on the new network topology

Allow queuing at the physical interface level handle thetraffic discard during congestion


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Challenge #2 SolutionOption 1: Both Design and RSVP BW=0Challenge #2 SolutionOption 1: Both Design and RSVP BW=0

All bypass tunnels are routed based on 0 bw requirement forprotection.

Shortest path results. An efficient network resource usage results due to 0 rsvp bw. Queuing delay could occur during congestion.


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Challenge #2 SolutionOption 2: Full Design BW and 0 RSVP BWChallenge #2 SolutionOption 2: Full Design BW and 0 RSVP BW

All bypass tunnels are routed based on 100% primary tunnel bwrequirement for protection.

Best paths for full protection will result. An efficient network resource usage results due to 0 rsvp bw.

Propagation delay could be increased for some bypass tunnels.


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Alternative Solution

Create multiple bypass tunnels Set maximum bw and subscription ratio for bypass

tunnels.

Load balance among all available network resources Minimize congestion

Prevent losing all tunnels during multiple failure

scenarios


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Challenge #2 Alternative Solution Multiple Bypass TunnelsChallenge #2 Alternative Solution Multiple Bypass Tunnels

Full BW for bypasstunnel design

Low RSVP BW toconserve network

resource Set maximum protectionBW for bypass tunnels

Set maximum number ofbypass tunnels allowed

A possible scenario is to use multiple (4) OC48 trunks to protect asingle OC192 trunk

Load balancing is desired among 4 OC48 trunks

This scheme could preserve 75% of the traffic even when the OC192and one OC48 are down at the same time


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Description

Current MPLS network does not have any knowledge of thephysical layer topology, so the auto-configured FRR maybe put on the same physical transmission facilities as theprimary route of the LSP

Manual configuration of individual FRR, even using node/linkprotection scheme, can be error prone

Admin Group function is the ideal and logical choice formarking the facilities. However, existing RSVP TE extensiondoes not include Admin Group


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Solution

Use fate sharing function to group trunks based on

physical topology Fate sharing allows for manual categorization of trunks

When constructing bypass tunnels, router will avoid links

in the same group as the protected link Juniper fate-sharing and Cisco Share Risk Link Group

(SRLG) features are vendor-specific implementation

Create explicit bypass paths using WANDL tool to ensurefacility diversity


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Challenge #3 Solution Facility GroupingChallenge #3 Solution Facility Grouping

Automatically constructed facility groupingduring parsing of the configuration files

User may add new facility grouping to studyits impact on bypass tunnel design

Specify facility diversity for FRR auto design

Three OC48 ports on

the same PIC


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Challenge #3 Solution FRR Design with Facility DiversityChallenge #3 Solution FRR Design with Facility Diversity

Primary tunnel path in yellow

and NLP bypass tunnel in green With facility diversity Bypass tunnel avoids link

in the same facility due toadded constraint

W/o facility diversity

Bypass tunnel useslink in the same facilitydue to CSPF


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Description

How to design LSP that resists re-routing in a FRR-enabled

network environment Customers with ultra-delay sensitive applications who do not

want to be placed on sub-optimal route

Customers prefer to be notified of the failure and switch to

alternative network/provider

Solution

Dedicate a set of do not re-route LSPs Disable the FRR at the LSP head end while maintaining the

node/link protection scheme network wide


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Challenge #4 Solution LSP Tunnels Configlet GenerationChallenge #4 Solution LSP Tunnels Configlet Generation

Link-protection onrsvp interfaces

Mix of LSPs with NLPand without NLP

LSP with and

without NLP


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LSP Scalability ChallengeLSP Scalability Challenge

Designing a large MPLS core network that convergesmultiple feeder networks with thousands of trunkingLSPs for each feeder network

Designing and managing a network with tens ofthousands of LSPs is not practical for serviceproviders

Network performance and operator ability totroubleshoot are negatively impacted as the number ofLSPs increases


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A Practical Solution for LSP ConsolidationA Practical Solution for LSP Consolidation

Establish a full mesh of LSPs as the base LSP set inthe MPLS core network.

Set up feeder network logical trunking mesh aspseudowires within the base LSPs

Establish each set of PW with its own Class of Servicequeue for traffic management and policing

Build more than one set of base LSPs depending on

special requirements, e.g., do not re-route LSPs


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LSP Scalability illustrationLSP Scalability illustration

Tunnels routedthru a core link

Pseudowires riding on

a LSP tunnel

One fully meshed set of LSP tunnels Many PWs riding on a LSP tunnel All PWs passing thru a link are protected

by FRR NLP


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ConclusionsConclusions

FRR is a necessary and powerful tool in the MPLS TE-enabled network; however, it is also highly

complicated to implement MPLS TE is still a rapidly developing and evolvingtechnology with many gaps in the current standards

Although most major service providers have deployedMPLS TE-enabled networks, the learning curve is stillsteep, and there are many challenges ahead

A comprehensive FRR design and simulation tool likeMPLSView is needed to ensure proper BW protectionand efficient use of network resources


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Q&AQ&A

Ning So

Verizon Business

2400 N. Glenville

Richardson, Texas

[email protected]

Hao-Hsin Huang

WANDL, Inc

88 Centennial Ave.

Piscataway, NJ

[email protected]

Thank You!

building a highly adaptive resilient and scalable mpls1352

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