MPLS Protection and Restoration – Part 3 (Path Diversity in Secondary Paths)

MPLS Strict Path

Path Diversity in Secondary Paths

As we say in the following articles, while using Secondary LSP-Paths, sharing links between Primary and Secondary LSP-Paths must be avoided. We can say this term “Path Diversity”.

There are some methods to achieve Path Diversity. These methods are:

– Using Full Strict hop LSP-Paths
– Admin Groups
– Shared Risk Groups

Using Full Strict hop LSP-Paths

Primary and secondary LSP-Paths are configured with fully strict hops in this method. This is difficult to configure and cause a huge operational overhead in large scale networks. Troubleshooting is also difficult in this method. But this method can be a good choice for small scale networks, because there are limited number of redundancy options.

While using full strict hop methods, redundant paths can not be used. There is only one option to do this, using two secondary paths. But this is more configuration overhead. MPLS FRR (Fast Reroute) is also the other solution for using redundant paths in the topology. We will talk about MPLS FRR (Fast Reroute) in the following posts.

Let’s see how to configure strict hops in Alcatel-Lucent 7750 Service Router according to below topology.

Strict Path, primary path, secondary path,MPLS Recovery
 

Paths with Strict Hops
 

primary “primary_path”. hop 1 10.1.0.1 strict hop 2 10.3.0.1 strict hop 3 10.5.0.1 strict no shutdown exitprimary “secondary_path” hop 1 10.2.0.1 strict hop 2 10.4.0.1 strict hop 3 10.6.0.1 strict no shutdown exitlsp “toRouterB” to 2.2.2.2 primary “primary_path” exit secondary “secondary_path” exit no shutdown exit

Admin Groups

With this Admin Groups method, redundant links are assigned to different Admin Groups. Primary and Secondary LSP-Paths are configured loose hops that exclude either one of the groups. Admin groups can be asymetrics.

In the below example, the Primary LSP-Path can use any of the links in the upper plane. And the Secondary LSP-Path can use any of the links in the lower plane.

Admin Groups, primary path, secondary path,MPLS Recovery
 

Admin Groups
 

A:RouterX>config>router>mpls# —————————— admin-group “UP” 1 interface “toRouter1” admin-group “UP” exit interface “toRouter2” admin-group “UP” exit

You can check the other parts of these MPLS Protection and Restoration Article series below.

MPLS Protection and Restoration – Part 1
MPLS Protection and Restoration – Part 2 (End-to-End Protection, Secondary Paths)
MPLS Protection and Restoration – Part 3 (Path Diversity in Secondary Paths)
MPLS Protection and Restoration – Part 4 (Local Protection, Fast Reroute)
MPLS Protection and Restoration – Part 5 (Fast Reroute Protection Types)
MPLS Protection and Restoration – Part 6 (RSVP Objects Used for MPLS Fast Reroute)
MPLS Protection and Restoration – Part 7 (Verification Commands on Alcatel-Lucent Routers)
MPLS Protection and Restoration – Part 8 (Actions After the Failure)
MPLS Protection and Restoration – Part 9 (Convergence Factors)
MPLS Protection and Restoration – Part 10 (Juniper Configuration Samples)
MPLS Protection and Restoration – Part 11 (Juniper Configuration Samples)
MPLS Protection and Restoration – Part 12 (Juniper Configuration Samples)
MPLS Protection and Restoration – Part 13 (Juniper Configuration Samples)


…YOU CAN REACH ALL THE “MPLS” ARTICLES AND CONFIGURATIONS BELOW…

MPLS Basics
What is MPLS?
Enabling MPLS on Cisco Router

MPLS Label Distribution Protocol, LDP
MPLS Label Distribution Protocol, LDP – Part 1
MPLS Label Distribution Protocol, LDP – Part 2
MPLS Label Distribution Protocol, LDP – Part 3 (Configuration on ALU)
MPLS Label Distribution Protocol, LDP – Part 4 (ECMP)
MPLS Label Distribution Protocol, LDP – Part 5 (Export and Import Policy, Prefix Aggregation)
MPLS Label Distribution Protocol, LDP – Part 6 (T-LDP)
MPLS Label Distribution Protocol, LDP – Part 7 (CR-LDP)

MPLS, RSVP-TE
MPLS, RSVP-TE – Part 1
MPLS, RSVP-TE – Part 2(Alcatel-Lucent Configuration)

MPLS Protection And Restoration
MPLS Protection and Restoration – Part 1
MPLS Protection and Restoration – Part 2 (End-to-End Protection, Secondary Paths)
MPLS Protection and Restoration – Part 3 (Path Diversity in Secondary Paths)
MPLS Protection and Restoration – Part 4 (Local Protection, Fast Reroute)
MPLS Protection and Restoration – Part 5 (Fast Reroute Protection Types)
MPLS Protection and Restoration – Part 6 (RSVP Objects Used for MPLS Fast Reroute)
MPLS Protection and Restoration – Part 7 (Verification Commands on Alcatel-Lucent Routers)
MPLS Protection and Restoration – Part 8 (Actions After the Failure)
MPLS Protection and Restoration – Part 9 (Convergence Factors)
MPLS Protection and Restoration – Part 10 (Juniper Configuration Samples)
MPLS Protection and Restoration – Part 11 (Juniper Configuration Samples)
MPLS Protection and Restoration – Part 12 (Juniper Configuration Samples)
MPLS Protection and Restoration – Part 13 (Juniper Configuration Samples)

 

 

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