Multihoming Suggestions w/o at Least a /24?

An anonymous reader asks: "I work for a small company who is looking to get a multihomed Internet connection for redundancy. The logical conclusion would be to get another internet connection to another provider. However, in the case of a primary connection failure, we need to be running BGP to have our internally-hosted sites still accessible to the Internet via the 2nd connection. The problem is that we only have a /28 (16 IPs), which is too small to make it past most route filters, and would then mean that we still couldn't be reached if the primary T1 is down. So, what's our options? (and no, lying and getting a /24 isn't a valid choice)"

Comments

It depends on the services...

[amorsen]

The obvious choice is to get a second set of 16 addresses on the other connection, and then make your DNS server send out addresses to whichever connection currently works. Not all services like switching addresses, and sessions break when doing failover, but it might work for you. If you only care about outgoing traffic, load-balancing and failover is fairly easy to do and there are lots of products to help. Again, outgoing sessions will get killed if they happen to use the link that breaks.

Fake it with DNS?

[zcat_NZ]

Set up your servers with a different IP for each route. Set up DNS inside your network so that the DNS server on one interface returns IP addresses that go through that interface, and vice-versa.. with a short expiry time.

If the main link goes down, so does the primary nameserver. The secondary nameserver (on the backup link) then returns IP's that are routed through the backup link.

This should work, but it probably goes against several RFC's..