Is there some technical reason that BGP is not an option? You could allow them to announce their AT&T space via you as a secondary. -Randy ----- Original Message -----
This may sound like dumb question, but... I'm used to asking those.
Here's the scenario
Another ISP, say AT&T, is the primary ISP for a customer.
Customer has publicly accessible servers in their office, using the AT&T address space.
I am the customer's secondary ISP.
Now, if AT&T link fails, I can provide the customer outbound Internet access fairly easily. So they can surf and get to the Internet.
What about the publicly accessible servers that have AT&T addresses, though?
One thought I had was having them use Dynamic DNS service.
Are there any other solutions, short of using BGP multihoming and having them try to get their own ASN and IPv4 /24 block?
It looks like a few router manufacturers have devices that might work, but it looks like a short DNS TTL (or Dynamic DNS) needs to be set so when the primary ISP fails, the secondary ISP address is advertised.