ISP inbound failover without BGP

Tue Mar 4 01:50:26 UTC 2014

Depends on the application,  

SIP, VPN, SMTP, etc just setup both IPs and let the end-user application figure it out (SIP-UA register to both IPs for example)

HTTP/HTTPS setup a proxy server in a colo that is multi-homed to frontend the requests. Then it can load balance traffic over both IPs.

DNS TTL ‘tricks’ are just that, they work ‘kinda’

Fatpipe?   Crazy expensive IMHO but I hear they work ok.

-Matt

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Matthew S. Crocker
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On Mar 3, 2014, at 8:11 PM, Eric A Louie <elouie at yahoo.com> wrote:

> 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.
> 