Maximum length for a http url?

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Jun 24th, 2010
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I have a website that I cannot access via any of the Cisco 877 routers I have installed, 10 in total.  When I try to access this url

The page does not display after a period of about 3 minutes waiting for the browser to retry.  The question is, is there a maximum length on a url that Cisco implement in the Advanced Security IOS for this model?

I have tried the url on a Cisco 1841 and it works fine with a very similar config.

Im sorry if this isnt the right place for this post, please redirect me if there is a better forum for this!



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Diego Armando C... Thu, 06/24/2010 - 14:29
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This problem might be related with mtu maybe or mss. from the 800 routers... does the traffic pass a GRE tunnel?

kyle.heath Thu, 06/24/2010 - 14:31
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It doesnt no, but I do have an IPSEC tunnel to another 877 at a remote site.  I set the mss on the ATM0.1 interface to 1300 on a ADSL2 circuit, this has improved the IPSEC tunnel significantly in terms of fragmentation.

I will try upping the mss back to 1452 again and test.  Thanks

kyle.heath Thu, 06/24/2010 - 14:45
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I have just tested further and the issue seems to only fail from Windows XP, I have tested from a Windows 2008 Server and this is successful.  I have changed the command on the ATM0.1 interface to

no ip tcp adjust-mss 1300

and the issue still occurs.  Its really making me think this one as the site is a government website and worked for my customer for months until last thursday so I can only think that something changed at the website level or hosting otherwise it wouldnt have worked before.

Diego Armando C... Thu, 06/24/2010 - 14:52
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Go ahead and do a debug for ICMP .. If you see this messange

ICMP: dst (x.x.x.x) frag. needed and DF set 
unreachable sent to x.x.x.x  this is a fragmentation issue.
kyle.heath Thu, 06/24/2010 - 15:07
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Thanks, I will try that tomorrow.  I just can't work out why it works on Windows 2008 and not Windows XP behind the same router.


Kyle Heath


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