Re: SV: Hot Standby

Jordan Mendelson writes:
> Mattias Paulsson wrote:
> > The last couple of days I've been researching ways to solve a much
> > similar problem and I've come up with the following URLs that might
> > be of help:
> >
> > Linux HA Project: http://www.henge.com/~alanr/ha/
> > EddieWare http://www.eddieware.com
> > Fake: Redundant Server Switch http://linux.zipworld.com.au/fake/
> >
> > Within a couple of days I will have tested these methods but until
> > then they're just pointers that might be useful.
> >
> > There is probably expensive hardware that will do the trick but
> > let's try a simpler approach, right?
>
> Maybe my reply didn't get through.

It got through to me, anyway, it's just that people had already started
replying.

> Current developmental versions of Squid
> support Cisco WCCP 1.0. WCCP is a very simple protocol which provides high
> availability and autodetection of cache servers. This is how it works:

Yes... however, part of the original suggestion was that the Squid
server should run as the default gateway and router for the network.
IMHO, that's not a good idea, and WCCP wouldn't help with it anyway.

> On your Cisco, enable WCCP (11.1 or later):
>
> rtr# conf t
> rtr(config)# ip wccp enable
> rtr(config)# int e0
> rtr(config-if)# ip web-cache redirect
> rtr(config-if)# end
> rtr# copy running-config startup-config
>
> With Squid 2.3, add the following to your config file:
>
> wccp_router your.routers.ip.address

This is very cool. Thanks for implementing it, and thanks for the
useful info! I'm saving it for my own reference.

> Squid should automatically start sending keepalive messages to the
> cisco router. The Cisco router will proxy requests over to your Squid
> server as long as Squid keeps sending keep alives. If Squid dies or
> the machine crashes, the router will use another WCCP enabled cache
> or route out normally.

I note that you have an implicit assumption that the Cisco is a lot
less likely to crash or fail catastrophically than the Squid software
or hardware. I believe this to be quite correct!

That is exactly why you don't want the Squid IP address to be the
default gateway.

  -- Clifton

-- 
 Clifton Royston  --  LavaNet Systems Architect --  cliftonr@lava.net
        "An absolute monarch would be absolutely wise and good.  
           But no man is strong enough to have no interest.  
             Therefore the best king would be Pure Chance.  
              It is Pure Chance that rules the Universe; 
          therefore, and only therefore, life is good." - AC