Strange network problem accessing Ebay and versiontracker websites

All, I know this probably isn't the best forum for this question but I'd
like to rule out a network problem before I tell a customer he has a PC
problem. I run a small CLEC network that is single homed to BTN for
transit. I have 3 sites all interconnected via DS3's and provide DSL
services from each site. From anywhere on my network we have problem
with Ebay and but only on certain browsers. IE on a
windows machine can access these sites without any problems, but Firefox
on the same machine cannot open the websites (Ebay can be opened with
addblocking software installed). On a Mac the only browser that works
for these sites is Opera. With this knowledge I would say it is
something with the coding on the website, but if I take the same machine
and connect it to another network other than mine (Verizon, SBC and
local municipal wifi have been tested) everything works fine.

Can anyone give me any suggestions as to what routes to take to
troubleshoot this? Logic tell me that is I have reach ability and one
browser work but another doesn't it's a software problem with either the
browser or the site, but being able to take the same machine to another
network and have it work points to a whole different problem.

Could this be a MTU issue?

Shane Owens
DNA Communications Inc
601 1st Ave
Rochelle, IL 61068
work (815)562-4290 ext 201
mobile (815)793-3822

It sounds like that is a possibility. Are the DSL users being served by PPPoE? Setting the IP MTU on your PPPoE access template, depending on whose gear you're using to provide the servide provider end of your DSL services, to 1492 may help.


For what's it's worth you could use ping and the "don't fragment" switch to test MTU sizes.


Justin M. Streiner wrote:

Sounds a whole bunch like you have a PMTUD (Path MTU Discovery) issue.

Change the MTU on a host to be smaller and see if this fixes the issue... If it does, there are a bunch of networking tricks you can play to fix it for all of the customers. MSS rewrite is one, clearing the DF BIt on all packets is another -- these are various version of icky...