controlling traffic path on host bases in EBGP

[abahl]

We have a requirement of routing few hosts from only one EBGP link, by this we want to achieve that both inbound and outbound traffic from selected hosts will be forwarded only from the desired link and not from the other, and if the desired link is down, the inbound and outbound traffic from the selected hosts should be dropped.

If this was required for larger no. of hosts, we could have done ip prefix list filtering for one complete Class C address space, but we need to do this selective filtering for 10 - 15 hosts only.

Is there any way to achieve this, please help.

[abahl]

Can anybody help in solving this problem.

Thanks,

Anuj

[ruwhite]

Probably the only way to do this is to advertise a very long length range covering just these hosts, or to advertise host routes for them. Are the eBGP connections to a service provider? If so, you're not going to be able to advertise anything shorter than a /24.

As for dropping the traffic if the primary link is down, that is going to depend on whether or not these hosts belong to a larger set of addresses which are also reachable via the other link. If they are, it's going to be difficult to impossible not to get this traffic when the primary link fails.

My general suggestion would be to number these hosts within their own address range, and set up the advertisement of that address range so it is only reachable through the one link.

Russ

[abahl]

Thanks for your reply.

we have four /22 supernets being advertised on to the Internet.

Our EBGP peering is with tier 2 ISPs. We wanted to route (both INBOUND AND OUTBOUND) 10 - 15 hosts on a single EBGP link with no fallback, these hosts are a part of one /22 supernet.

one possibility could have been using the latest feature of conditional advertisement with route maps, but as our router contains a default route, therefore this solution is not viable.

Please guide if something can be done in this regard.

Anuj