[j-nsp] Loop Free Alternates topology recommendations

[David Ball]

  I'm having to build RSVP-signalled LSPs to non-adjacent nodes in order to
improve LFA coverage for OSPF and LDP, and am using the 'backup' knob in the
label-switched-path definition to ensure OSPF can use it.  Still in the
design/test phase here, but an engineer at Juniper proof-of-concept lab in
Boston showed me the functionality once and it seemed to do the trick.  See
here, if you haven't already:

http://www.juniper.net/techpubs/en_US/junos10.1/topics/task/configuration/ospf-rvsp-lsp-backup-paths-configuring.html

  Adjusting metrics may help, but I wonder about scalability
(administratively speaking) if your network changes much (from a
number-of-devices perspective).

David


On 17 December 2010 13:16, Clarke Morledge <chmorl at wm.edu> wrote:

> I wanted to resurrect an older thread regarding the Loop Free Alternates
> feature now available in Junos for OSPF and IS-IS.
>
> http://www.mail-archive.com/juniper-nsp@puck.nether.net/msg09719.html
>
> I am wondering if anyone has any pointers regarding what type of topologies
> do not work so well and why.
>
> I am running LFA in an environment where I know that I have multiple paths
> existing to where I need it, but unfortunately, I am not getting the type of
> backup coverage that I would like.
>
> For example, certain types of square topologies do not work well for some
> reason, but I am wondering if making link cost changes could rectify this
> problem.
>
> Clarke Morledge
> College of William and Mary
> Information Technology - Network Engineering
> Jones Hall (Room 18)
> Williamsburg VA 23187
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