[j-nsp] Junos MPLS question

[Hannes Gredler]

if the link-layer b/w R2,R3 support vrf-table-label
then i'd configure vrf-table-lable on the egress
VRF to make the load-balancing hash-calculation
entirely dep. on IP header fields where you have
more bits available for the hash-calculation (read: randomness)
compared the MPLS/IP egress lookup that was recommended
in a previous posting.

/hannes

Sorin CONSTANTINESCU wrote:
> Hi,
> 
> 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 (10.255.255.69, let's say) via 4
> qualified-next-hops (assiociated with the 4 links). On R1, i have:
> 
>    10.255.255.69/32 193.226.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.
> 
> Thanks.
> 
> PS: I have opened a case with JTAC a few days ago, bot no luck yet.
> --
> Sorin CONSTANTINESCU
> JNCIS-M, CCNP
> consta at gmail.com
> 
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