BGP MULTIHOMING

rooland12 · ‎02-10-2012

Helo everyone,

I need help in setting up the routing policy for multihoming. The scenario is we have 1 router connected to ISPA and ISPB. For few destinations I have given higher weight attribute so that it exit through ISPA and few other destinations through ISPB(higher weight attribute) .

How can I make sure that the reverse route is same as the forward path. For example: For Destination1 packet is exiting through ISPA ,then how to make sure that return traffic comes through ISPA only but not through ISPB.

I hope you understand the scenario

Regards,

Rooland

rooland12 · ‎02-11-2012

Any input would be helpful....

jgraafmans · ‎02-11-2012

You can use AS path-prepending to advertise a longer AS path to one provider and/or BGP communities to influence the local preference on the provider site.

See http://blog.ioshints.info/2008/02/bgp-essentials-as-path-prepending.html for more information about both options and the configuration of the AS-path prepend option.

Regards

Jasper

rooland12 · ‎02-11-2012

Hi Jasper,

Thanks for the response...

But I think I can use AS path-prepaending/BGP comunities only in ACTIVE/STANDBY connection style.

In my scenario, both ISP's are active .

My requirement is that traffice going out of ISP A should return through ISP A, vice versa traffice going out throught ISP B should return through ISP B.

jgraafmans · ‎02-11-2012

Routing is uni-directional so this is not possible because you cannot influence the way the returning traffic flows based on the source addres of that returning traffic.