Re: [squid-users] Squid - Dual WAN Links

From: Amos Jeffries <squid3_at_treenet.co.nz>
Date: Tue, 10 May 2011 13:05:58 +1200

 On Mon, 9 May 2011 13:48:38 +0100, John Sayce wrote:
> I have two squid proxy servers. I use a PAC script to assign the
> proxy servers with one being a primary and one being a failover.
> This
> works great but I would like to achieve a similar configuration with
> the access to the WAN links from proxy servers. I have two Wan DSL
> Links and two dsl routers. I'm open to changing this configuration
> but I'd like to avoid a dual wan router as this would mean no
> redundancy if the router fails.

 Wire-level operations are *way* beyond Squid. May as well ask atoms
 whether they are all spinning left or right on the third row of your
 nose. The OS can do absolutely *anything* to the packets underneath
 Squid. Including sending each *individual* packet out a different NIC
 with a NAT'ed address Squid knows nothing about.

 If you have remote upstream parent Server at the other end of each of
 those WAN links then configuring them as cache_peer already does this
 peer monitoring and failover at the HTTP level. Nothing special needed
 beyond ICP/HTCP and ICMP. That is as close as Squid gets to link control
 and if the OS decided to route to both peers via Vancouver there is
 nothing Squid can do about it (my pet peeve today).

>
> At current I have no requirement for load balancing although in
> future I may assign bandwidth sensitive applications to the failover.

 When you do get to this need look at QoS first. Squid can mark
 connection scope to label various flows for QoS handling at the OS
 level.

> I could probably write a script to check the wan links and the
> routers which could then change the network settings and restart if
> required but this seems a rather inelegant solution. Is there a way
> of doing this with squid or has anyone got any better ideas?

 This is precisely how you will have to do up/down monitoring. The OS
 network manager provides up/down hooks for each interface, add a script
 there to reconfigure Squid when the NIC state changes.

 Amos
Received on Tue May 10 2011 - 01:06:04 MDT

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