[j-nsp] RSVP signaled LSPs across LACP bundles

[Daniel Rohan]

Hi all,

Quick question for those who might have run across this.

I have a 4x10Gb backbone based on Juniper MX routers. The 10Gb interfaces
are LAG'd with LACP using the default layer4 hash. It works wonderfully
under normal conditions.

I'm using RSVP to signal dedicated LSPs for a bunch of
pseudowires/l2circuits across our network.  The bandwidth for a few of
these pseudowires is as high as 10Gbps.

When one of the 10Gb LSPs starts to get close to 9.4 or 9.5 Gbps of
utilization, we start to see other customer traffic drop, RTT latency
increase etc. The 10Gb flow starts to drop packets as well.

The cause appears to be obvious: the 10G flow is getting hashed onto one of
my four links in the LACP bundle, and there it stays (it's a single TCP
session). Any other customer traffic that is unlucky enough to be hashed
onto that link contends with that mammoth flow and everyone loses.

I'm trying to find a way to work around this and looking for ideas.
Per-packet spray hashing is not an option. Would adaptive load balancing
help? Something else? I'm trying to avoid the scenario where I have to
dedicate specific 10Gb links just for these bursty psuedowires in order to
protect other traffic. That seems regressive, although the remainder of
this customer traffic *would* handily fit on a 30Gb LACP bundle.

-Dan