Re: [squid-users] Failover to upstream when direct link down

On Wed, 17 Nov 2010 20:40:34 +0000, Paul <news_at_pointdee.co.uk> wrote:
> We currently have a direct connection to the internet and a connection
> to an upstream proxy via a separate connection. The majority of our
> users connect to a downstream proxy which connects to our squid 2.7 on
> openSUSE 11.3 which then forwards these requests to the upstream proxy.
> The rest of our users connect directly to squid and have their requests
> serviced by the direct connection.
>
> Direct Upstream
> \ /
> \ /
> Squid
> / \
> / \
> Users Downstream
> \
> \
> Users
>
> The direct connection occasionally drops out and so in this situation I
> would like ALL requests to be serviced by the upstream proxy until the
> problem is resolved and then switch back to the current running config
>
> A search of the archives suggest that this isn't available natively in
> squid but I thought I'd ask to see if anyone else has this situation or
> knows of a solution

It is supported.

You configure the upstream proxy as a parent and set the "prefer_direct"
directive to ON.
This will cause Squid to attempt the direct link first before the parent
proxy, the normal behaviour is to prefer parents over direct.

Squid 2.6 has problems with settings sent to peers on certain request
types. The recent releases of 3.x and 2.7 have these known issues resolved.
Any remaining are ones we want to hear about.

The hierarchy_stoplist and nonhierarchical_direct directives are worth
removing in this scenario, which will permit the dynamic and HTTPS requests
to continue working through the parent.

Amos
Received on Thu Nov 18 2010 - 03:33:57 MST