[c-nsp] Load Balancing via BGP outbound at Colo

[Loopback]

All


We would appreciate some ideas for the best method of implementing limited
traffic engineering via BGP for our current network.  We have two EBGP
routers in the same physical location with and IBGP connection between them,
each are dual homed to 3 Tier 1 ISP's and single homed to one other ISP.
There is very little transit traffic, almost all is outbound responses from
customer servers in our colo facility.


  Router A

A -----------10Mb/s-------------- ISP #1
A -----------10Mb/s---------------ISP #2
A -----------10Mb/s---------------ISP #3 
A -----------10Mb/s---------------ISP #10
|
|
|  Router B
|
B -----------10Mb/s-------------- ISP #1
B -----------10Mb/s---------------ISP #2
B -----------10Mb/s---------------ISP #3
B -----------10Mb/s---------------ISP #20 


We currently do not enforce any PBR, our outbound route selection algorithm
is default "shortest AS-PATH"  destination network with the addition of
"BGP Multi-Path" so that any return traffic to routes with equal AS-Path 
lengths will balance among all the connections with equal cost.


We are going to upgrade the bandwidth on the "ISP #1" connection to a GbE on
both routers and leave the others at the current bandwidth.  This will be 
much less expensive connection per Mb/s, for that reason we would like to
prefer it for the return path for all outbound traffic to any destination
that does NOT originate from with the AS of one of our other directly 
connected providers.  Our thoughts is that approach will combine both
routing efficiency and economy.

The question is the best method to accomplish this using BGP, and preferably
without having to coordinate MED's or Community values with our providers. 

Looking forward to hearing your opinions.


Jack