default routes on Ciscos

Sat Jul 19 20:14:39 UTC 1997

> Just curious if anyone out there knows of a way to configure default
> routes on a per interface basis on a Cisco.  So that different interfaces
> had different default routes statically defined.

Others here have pointed out that this can be done using policy based routing.
It's pretty hard to do per-interface default routes when you're not the sink
for the packets, though, since there's otherwise no protocol control block or
other state to hang the outbound default on.  I suppose you could just do round
robin for your outbound traffic.

If you're using a BSD/OS, NetBSD, or FreeBSD machine and you're doing multi-
homed web service (which _does_ give you protocol control blocks to use to
hold your default route binding for outbound packets), there's some free code
available to support per-interface default routes.  It's a small change to the
kernel and an even smaller one to the "route" and "netstat" commands.

See ftp://ftp.vix.com/pub/vixie/ifdefault/ for source code and SF NANOG slides.