Re: ISP inbound failover without BGP

[Matthew Crocker <matthew () corp crocker com>]

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 () 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.