[j-nsp] Junos MPLS question

Sorin CONSTANTINESCU consta at gmail.com
Sun Dec 11 11:39:56 EST 2005


I have a setup like this:

R1 -> R2 -> R3 ->R4

- R1,R2 and R3 are in an MPLS Domain. R4 is outside.
- between R3 and R4 are 4 links (load-balanced)
- R1 - Cisco
- R2, R3, R4 - Juniper

The goal of this setup is to have traffic from R1 (inside VRF) to go
to R4 ballanced on the 4 links between R3 and R4.

I have configured a VRF in R1 and R3. In R3 i have a static default
route to inet.0. Unfortunatelly, i cannot redistribute it via MBGP to
R1, so i use 4 fake routes with qualified-next-hop, which are
redistributed in BGP. In R1, i route 0/0 towards the 4 next-hops
received earlier via MBGP.

All is Ok, but sometimes i hit a bug on the cisco router, and traffic
is no-more ballanced, and all traffic from R1 to R4 goes only on one
link (instead of four).

I tried routing one prefix (, let's say) via 4
qualified-next-hops (assiociated with the 4 links). On R1, i have: 193.226.x.y nolabel/265056
                             193.226.x.y nolabel/265056

On the R3, i have:

=== cut here ===
adonay at R3> show route label 265056

mpls.0: 86 destinations, 86 routes (86 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both

265056             *[VPN/170] 3d 14:49:40
                      to x.x.x.x via so-0/1/0.0, Pop
                      to x.x.x.x via so-0/1/1.0, Pop
                    > to x.x.x.x via so-0/1/2.0, Pop
                      to x.x.x.x via so-0/1/3.0, Pop

adonay at R3>
=== and here ===

Although it looks very good, when tested, traffic is not load-balanced
across the 4 links, but goes out one of them only.

Any help is greatly appreciated.


PS: I have opened a case with JTAC a few days ago, bot no luck yet.
consta at gmail.com

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