I was going through a deployment scenario which i had deployed earlier and looking at Junipers vs cisco implementation of FRR, i was sort of confused. Juniper are fairly easy to implement, you mention FRR knob at the head-end Router and that is going to be it for your FRR.

The only think which you may need to make sure is all the down stream routers should be capable of understanding this knob.

Lets look at the topology.


Now, Without enabling any Fast-Reroute Knobs, lets see how Path / Resv Message looks like.

Below is the configuration


The path and Resv Messages are exchanged and here is how it looks like – Remember FRR is yet to be enabled

path-message-without-frr-on-headendR1 resv-message-witout-frr-onhead-end

Now, Lets enable FRR and see what changes would occur


Change in the Path-Message sent by R1

Fr-knob-enabled for communication in path-messagee

Now follows a series of computation

2 label comparision Final-Label  last-label

When disabled we can see the utilization of Detour-Label/Path

detour label in R2

detour label in R2

This is how Juniper is implementing things,

References –

https://tools.ietf.org/html/rfc3209#section-4.1 – RSVP-TE: Extensions to RSVP for LSP Tunnels (object-id 16)

https://tools.ietf.org/html/rfc4090#section-3.1 – Fast Reroute Extensions to RSVP-TE for LSP Tunnels