BGP per-flow load balancing between eBGP and iBGP learned prefix

Andy Litzinger andy.litzinger.lists at gmail.com
Tue Sep 16 15:33:38 UTC 2014


Hello,

I have a Load Balancer that uses a default route to a VRRP IP hosted
between two Juniper MX80 routers.  Each MX router has a single BGP feed
from the same provider and each session is currently receiving only a
default route.

I'd like to load balance my outbound traffic across the two links.  More
specifically I want to balance traffic to a particular prefix across the
two links so even if i was receiving full routes trying to manually split
prefixes to a second upstream VRRP instance wouldn't help.

I believe the typical way to do this would be to run an IGP between the LB
and the MX's so that each MX advertises a default route to the LB and let
ECMP take care of it.  I'm not averse to this long term, but I have a short
term need and the LB requires a license to participate in an IGP.  Is there
another way?  I should note that the LB will not let me enter multiple
default or identical static routes so I can't try spinning up a second VRRP
session and adding a second default route on the LB to it.

Is it possible to let BGP do the load balancing?  From what I can tell this
would be trivial if both of the provider links were terminated on the same
router via a few multipath config lines but because they are on different
routers I seem to be running into the "eBGP > iBGP" Path selection criteria
which prevents the routes from being equal.

I appreciate any ideas!

regards,
 -andy


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