Re: foreign host name with NAT L4 switch

From: Alex Rousskov (rousskov@measurement-factory.com)
Date: Thu May 10 2001 - 08:15:41 MDT


On Thu, 10 May 2001, Joseph Mack wrote:

> I can connect client-host (it looks like you call this robot-host)
> with simple.pg. If I connect via an L4 switch using NAT, the
> servers initially reply, but give out "foreign host name" errors
> and then stop delivering packets. I assume because of NAT, the
> dest IP's have changed.

If I understand your setup correctly, you tell robots to contact the
server at address VIP, and you tell the server to bind to address S.
That will not work "as is" with Polygraph 2.5. In the next release,
you will be able to tell Polygraph that VIP actually maps to S.

Meanwhile, you can trick Polygraph by configuring a fake server agent.
That fake agent should be identical to the server agent you are using
now, but it should bind to the VIP address. That agent will never be
created (because you do not have polysrv running on the switch), but
it will trick Polygraph into thinking that VIP is a valid server
address:

        Server srvReal = { ... }; // your current server configuration
        srvReal.hosts = [ S ]; // real server address

        Server srvFake = srvReal; // copy configuration
        srvFake.hosts = [ VIP ]; // use VIP address

        use(srvReal, srvFake);

This is a hack, and you may get some warnings/errors, but the test
should run OK. You should not use simple.pg for production tests, but
the same "fake server" approach applies to other workloads.

> PS: is there a search engine for the mailing list archives?
> I didn't find anything for "foreign" in the subject lines.
> If there was anything in the body of the messages I wouldn't
> have seen it.

There will be a search engine when we move the Web site to
www.web-polygraph.org. The new Web site is ready and will go live with
the 2.6 release, any time now.

Alex.



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