Transparent cache problem: clients cannot refresh pages!

Hello,

Is there a solution known for the following problem:

We are using Squid-2.3STABLE2 as a transparent cache (with Cisco router).
Everything works just fine, BUT clients with MSIE 5 browser are unable to
Refresh page when they need it - until that page expires in cache!

This problem doesn't exist if client was configured with explicit proxy
server, because in such case MSIE adds appropriate header in HTTP request.
If user pressed the Refresh button, this request is logged in Squid
access.log like
TCP_CLIENT_REFRESH_MISS
and user always gets new content (even if the object was cached and not
expired yet).

But when MSIE is not aware of proxy, it sends just a normal HTTP request
upon pressing Refresh button! So it looks like
TCP_IMS_HIT
and user gets the old content from cache.

Fine-tuning expiration parameters in Squid doesn't help. For example,
somebody may call users at 10:00am and tell them "hey guys, we've updated
price.htm on our site 5 minutes ago so you can take a look" - and users
_wouldn't_ wait even an hour until price.htm expires. They want it
immediately (and they are right).

Disabling caching for particular sites doesn't help also. There are 10s of
such sites, and list of sites is changing quickliy.

So I'd appreciate any feedback on this topic; it is unclear for me:
1) Can this problem be resolved _without_ reconfiguring user browsers ?
User browser tuning is simply impossible in our case (running ISP,
actually).
2) Evidently some component is violating HTTP standard. So is MSIE
violating the standard, or transparent caching is actually prohibited in
the standard ?
3) Does this problem exist on commercial transparent caches (like Cisco CE
Cache Engines, etc) ?

Thanx in advance for your feedback.

With best regards,
Alex
Received on Fri Jun 02 2000 - 05:35:33 MDT