[j-nsp] MPLS VPN Load-balancing

[Christian Martin]

NSP-ers,

I have a Cisco---Juniper pair connected over a pair of T3 links.  The  
Juniper acts as a PE and is pushing two labels for a specific route  
learned on the PE destined to a single remote PE well beyond the Cisco  
P.  The traffic is destined to several IP addresses clustered in this  
subnet (sort of like 10, 11, 12, 13) and the forwarding table shows  
that there are two correctly installed next-hops - same VPN label,  
different LDP label (we have applied several different types of  
hashings and of course have our forwarding table export policy in  
place).  Nevertheless, the Juniper is doing a very poor job load- 
balancing the traffic, and the Cisco is splitting it almost evenly.   
There is in fact a larger number of routes being shared across this  
link (about 20 or so VPN routes in different VRFs and thus different  
VPN labels – all sharing the same 2 LDP labels, but one particular  
subnet pair is exchanging quite a bit of traffic).  All of the  
addresses are unique within our domain.

Has anyone had issues with load-balancing a single subnet across an  
MPLS VPN link pair?  Note again that this is a PE-P (J--C) problem and  
that the IP addresses are all arranged locally.  I know Juniper are  
secretive about their hashing algorithm (can't lose any hero tests,  
can we?), but we are getting like 5:1 load share if we are lucky and  
are bumping up against the T3's capacity.  The box is an M10i.

As always, any help would be appreciated.

Cheers,
C

show route forwarding-table destination 10.160.2.0/24

Routing table: foo.inet
Internet:
Destination        Type RtRef Next hop           Type Index NhRef Netif
10.160.2.0/24      user     0                    indr 262175     2
                                                  ulst 262196     2
                                                 Push 74   600     1  
t3-0/0/0.1000
                                                 Push 74   632     1  
t3-0/0/1.1000


PE-P next-hop count (all showing load-balancing in effect)

show route next-hop 172.16.255.11 terse | match > | count
Count: 106 lines


monitor interface traffic

Interface    Link     Input bytes        (bps)      Output  
bytes        (bps)
  t3-0/0/0      Up    541252651233   (25667208)      691166913860    
(35611752)
  t3-0/0/1      Up    279149587856    (8737568)       24893605598       
(20112)


Note that the Cisco is doing 25/9 Mbps and the Juniper 35/.02.