[OpenAFS] Re: Redundant Internet links

Jaap Winius jwinius@umrk.nl
Sun, 19 Dec 2010 02:05:49 +0100

Quoting Derrick Brashear <shadow@gmail.com>:

>> ... Each database server should never consider that it has any other IP
>> address except one in particular. The single IP addresses that they
>> each use to reach their remote companions will never change either.  
>> Only the routing in between will occasionally change as needed when  
>> the
>> main links go down and up.
> Sure, but will any host's address for some other host be lower than
> its own address while
> at the same time that host itself *should be* the lowest host?
> (It's too early; Does that make sense?)

The addresses of the DB/file servers, as well as the addresses by  
which they are known each other, will always be the same.

Originally I wondered whether it would be possible to let the DB  
servers decide for themselves the routes by which they would contact  
each other, since each of the hosts on which they will reside will be  
multi-homed, but the answer to that is no: they can only know and  
contact each other via a single IP address (not two) because of the  
way the voting algorithm works.

So, now I'm just going to configure some lower-level routing to take  
advantage of the redundant links. I've set up a system with two  
default routes before, using Debian's iproute package, but this  
network will go one step further: when one site's main Internet link  
goes down, each of the other sites will still be able to reach it's  
usual IP address via an alternative static route.