nanog mailing list archives
Re: Stumper
From: Marshall Eubanks <tme () multicasttech com>
Date: Tue, 21 Jan 2003 17:35:31 -0500
Could this be a packet size issue ? You might try ping -s and see if, say, 1500 byte and 4500 byte packets get through.m On Tuesday, January 21, 2003, at 05:25 PM, Mark J. Scheller wrote:
I have run into a problem that has me completely stumped, so I'm tossing itout to NANOG for some help. Before I lay out the specifics, I'm not trying to point fingers at anyparticular ISP or vendor here, but this problem only exhibits itself in very specific configurations. Unfortunately, the configuration is common enough asto get unwanted attention from the higher-ups. Here's the particulars:Users that have Verizon DSL and a Linksys cable/DSL router have difficulties accessing sites on my network -- whether they are trying with http, https, smtp, pop3, ssh, ftp, etc., etc. Oh, but pings seem to be fine. Low latency, no loss. This is true even for access to a server brought up in the DMZ, tokeep the firewalls out of the equation.Doing some packet sniffing on the ethernet side of my router, I could see specific http requests never showed up (and the user saw the broken image icon). This was for an mrtg graph page with +/- 30 images. I saw the request for almost all the image files, save for one and the user reported the brokenimage icon for the one. So this looks and smells like a packet loss issue..... but who/where/how?Taking the Linksys out of the pictures (connecting their PC directly to theVerizon DSL modem) makes the problem go away.These same users report no trouble whatsoever accessing many other commonsites across the internet. Here's another interesting data point: when one user runs Morpheus (onany machine in his home network) he then has absolutely no problems accessingservers/services on my network. Other users with Linksys routers and, say cable modem, do not have this problem!So I'm looking for some pointers. What could I have done to my edge router (a Cisco 3640 if that helps any) that would make it drop packets from Verizon DSLcustomers with Linksys routers so long as they aren't running Morpheus? Mark J. Scheller (scheller () u1 net)
Regards Marshall Eubanks T.M. Eubanks Multicast Technologies, Inc 10301 Democracy Lane, Suite 410 Fairfax, Virginia 22030 Phone : 703-293-9624 Fax : 703-293-9609 e-mail : tme () multicasttech com http://www.multicasttech.com Test your network for multicast : http://www.multicasttech.com/mt/ Status of Multicast on the Web : http://www.multicasttech.com/status/index.html
Current thread:
- Stumper Mark J. Scheller (Jan 21)
- Re: Stumper fkittred (Jan 21)
- Re: Stumper Stephen J. Wilcox (Jan 21)
- Re: Stumper Marshall Eubanks (Jan 21)
- RE: Stumper Deepak Jain (Jan 21)
- Re: Stumper Mark J. Scheller (Jan 21)
- Re: Stumper William Warren (Jan 21)
- Re: Stumper Stephen J. Wilcox (Jan 21)
- Re: Stumper Steve Gibbard (Jan 21)
- Re: Stumper jeffrey.arnold (Jan 21)
- Re: Stumper hc (Jan 21)
- Re: Stumper Wayne E. Bouchard (Jan 21)
- Re: Stumper Miguel Mata-Cardona (Jan 22)
- Re: Stumper Dennis Boylan (Jan 22)
(Thread continues...)