[SGVLUG] Hosting a Site over multiple locations and public IPs

[matti]

Hi,

round robin works well to balance,

the problem comes when one ( or 1+ ) machine dies
and you need to drop it from the list

cisco and others had a number of solutions to
this...

a basic setup one would have a list of IPs in the
DNS tables, and the systems would also have their
own IPs. Each online system then would also answer
to one or more of the IPs on the DNS table...

i.e.

DNS IPs 1.1.1.1, 1.1.1.2

System IPs 2.2.2.21, 2.2.2.22

system 2.2.2.21 answers the requests to 1.1.1.1
and 2.2.2.22 answers the requests to 1.1.1.2

when one system dies the other takes over the
requests to the other DNS IP
( i.e. 2.2.2.21 dies, 2.2.2.22 then picks up
IP 1.1.1.1 as well as the one it already is
answering 1.1.1.2 )

this way round robin keeps on going around,
and something will answer...
( well you will lose some connection requests
during the switch.. but not bad solution )

best
matti