Depending on their business, using dynamic DNS providers could be a really bad idea. If they deal only with home users who won't even know, it'll probably work. If their customers are security-aware businesses, they probably block all sites hosted with dynamic DNS systems. Ray
Subject: Re: ISP inbound failover without BGP From: matthew@corp.crocker.com Date: Mon, 3 Mar 2014 20:50:26 -0500 To: elouie@yahoo.com CC: nanog@nanog.org
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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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.