Publishing www etc services via multi wan
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What is the sense behind having services like www and ftp and vpn published to the internet via multiple wan's ? With (A) records being static, what is the use of having alternate routes if the IP address in question is down because the line is down. Does this not mean that the service will also be down? Is multi wan then only usable for (MX) records and traffic originating from LAN?
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MX records should also work, but that and outbound traffic aren't the only valid cases. You could have multiple A records that work in a round-robin manner, or you might have some users who know enough to try the second hostname if the first doesn't work.
There are plenty of services which have built-in failover in the clients such as OpenVPN, citrix, etc. but that does take some extra configuration on the client side.
It's useful to many people, and for many different reasons, but those reasons may not be relevant in your case. :)
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I've always seen true multi-wan as advertising your single IP address space through your backup WAN provider to the internet. This space should be public and as long as the two ISPs peer properly to allow it, this is by far ideal in every way.
Round robin DNS is your secondary cludge to make use of two sets of IP addresses, but it works and is probably what I'll set up in my home datacenter when I get to it.
That's just my $0.02
–James
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I've always seen true multi-wan as advertising your single IP address space through your backup WAN provider to the internet. This space should be public and as long as the two ISPs peer properly to allow it, this is by far ideal in every way.
Round robin DNS is your secondary cludge to make use of two sets of IP addresses, but it works and is probably what I'll set up in my home datacenter when I get to it.
For that to work you need to get your own set of IPs and do BGP routing on both ISP links. For many, that can be cost-prohibitive, but it is the ideal solution.
