MPLS Protection and Restoration – Part 2 (End-to-End Protection, Secondary Paths) - www.ipcisco.com : www.ipcisco.com
You can Reach Our "CCNA Lab Courses with Packet Tracer" on Udemy.!!!
cisco-packet-tracer-ccna-adventure-1- cisco-packet-tracer-ccna-adventure-2-
Content Protection by DMCA.com

Protection Types

There are some different types traffic protections. In general we can divide these types into two groups. End-to-end Protection and Local Protection.

End-to-end Protection is using Secundary LSP-Paths as a backup, beside Primary LSP-Path.
Local Protection is the mostly used MPLS recovery mechanism, MPLS FRR (Fast Reroute).

End-to-End Protection (Secondary Paths)

In this model two LSP-Paths are used. One of them is Primary LSP-Path and the other is Secondary LSP-Path. Multiple secondary paths xan be configured. At the Head-End up to 8 LSPs can be configured. And 7 of them can be Secondary Path.

Traffic goes on Primary LSP-Path normally.And there is no load balacancing with Secondary Paths.

Whenever a failure occurs on the Primary LSP-Path, RSVP error is send to the LSP-path’s start point, to the Head-End. And the Secondary LSP-Path, which is standby (ready), is take over the traffic.

There are two types Secondary LSP-Paths. These are:
– Hot Standby Secondary Paths
– Cold (OR Non) Standby Secondary Paths
(default)

The Standby Secondary Paths are signalled before the failure. So after failure, it is ready to use. There is no need for signalling.

The Non Standby Secondary Paths are default for Alcatel-Lucent Service Routers.
It is not operational before the failure. After the failure, Head-End receive the Path Error message, and start thesignalling of Non-Standby Secondary Path. This is bad for recovery time, it is late. But it is less resource intensive, less RSVP session end labels consume.

Let’s see how to configure Secondary LSP-Paths, on Alcatel Lucent Service Routers for both Stanby Secondary LSP-Paths and Non-Standby Secondasru LSP-Paths.

You can check the Standby Secondary Path configuration on Alcatel-Lucent Service Routers below:

A:RouterA>config>router>mpls# 
------------------------------
lsp "toRouterD"
	cspf
	to 4.4.4.4
	primary "prim_path"
	exit
	secondary "stdby_sec"
		standby
	exit

Now let’s check the Non-Standby Secondary Path configuration:
(As you can see, there is onlymissing stanby command)

A:RouterA>config>router>mpls# 
------------------------------
lsp "toRouterD"
	cspf
	to 4.4.4.4
	primary "prim_path"
	exit
	secondary "stdby_sec"
	exit

As we say above, there can be multiple Secondary LSPs. But one of them must be Active at the same time. To select this active one, there are some parameters. These are:

– If it is Standby Secondary LSP, the one with the highest uptime will be active
– If it is Non-Standby LSP, the first one will be active

Beside this values, there is a “path-preference” parameter. If this “path-preference” is configured, then it is more preferable. It can be between 1 and 255. The default value is 255.

Here, there is an important point. Without a path-preference, if another better Secondary Path come online, still the selected one is used. Because it is not primitive. But if you use, path-preference, it is primitive and the better Seocndary Path can be online after.

Let’s check how to configure “path-precedence” on Alcatel-Lucent 7750 Service Routers:

A:RouterA>config>router>mpls# 
------------------------------
lsp "toRouterD"
	cspf
	to 4.4.4.4
	primary "prim_path"
	exit
	secondary "secondary-1"
		standby
		path-preference 10
		exit
	secondary "secondary-2"
		standby
		path-preferecen 30
	exit

Above, the “secondary-1” path will be selected as Active Secondary Path.

Here, it is need to be checked that, both Primary and Secondary LSPs use different paths. Because, if there is a common point in two LSPs, it means that two LSPs can be affected from only one point of failure. This check process can be done with different mechanism.

mpls end-to-end protection primary path and secondary path,MPLS Recovery

Primary and Secondary Paths in End-to-End Protection

There are some disadvantages of end-to-end protection. These are, its double usage of resources, unnecessary protection of some points and non-deterministic switchover time. To avoid these disadvantages, local protection is used. Sometimes both protection types used together.

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)


…You Can Join Our “IPCisco” Groups Below!!!…

You can Reach Our "CCNA Lab Courses with Packet Tracer" on Udemy.!!!
cisco-packet-tracer-ccna-adventure-1- cisco-packet-tracer-ccna-adventure-2-



About the Author
Gokhan Kosem is a telecommunation and network engineer. His ambition to IP networks and end-to-end system installation made him to prepare this web-site. By sharing his experiences about various networking protocols beside different system installation experiences and Cisco, Juniper, Alcatel-Lucent devices configurations, he is aimed to be helpful for his collegues in all over the world. He is currently lives in Istanbul, Turkey.

Leave a Reply


Copy Protected by Chetan's WP-Copyprotect.