Data Transfer Rates from Internet, drops to 40kbs on Cisco 1760

charles-moore · ‎12-30-2009

Hi,

Need a liitle help ! (Neo stated)

I have a 10meg Broadband conection and a 4 port Linksys Router which I am very happy with the performance. i.e I get on average between 400kps - to 1000kbps from most sites. when my PC is directly connected to the linksys Port. However I also have a Cisco router 1760 with a CISCO WIC-4ESW Fast Switch Module. located in my office, with an ethernet connection to the Linksys. If I connect my PC to the 1760, which is preferable because I have several Pc's which connect to the switch ports. However, when down loading files or docs I get on average 40kbs. I'm not sure why this is the case.

I have a syslog running at all times and there are no duplex Mismatch or speed errors.

Any advice would be appreciated.

Thanks

Charles

Igor Tumkin · ‎01-21-2010

Hi Charles,

It is hard to say something certain without much more details.

One of most probable issues is MTU limitation somewhere on the path and PMTUD (path MTU discovery) does not work for some reason.

E.g. ICMP is blocked on 1760, so PMTUD cannot work.

See http://www.cisco.com/en/US/tech/tk827/tk369/technologies_tech_note09186a0080093f1f.shtml

This document describes a typical example with MTU problem (GRE tunnel on the path, which does not matter in your case) and ways to diagnose and solve it.

Be aware, that there could be other reasons of your problem besides MTU - anything, which leads to packet drop.

Thanks,

Igor

charles-moore · ‎01-21-2010

Thanks for your help I shall have a look at the document.

Regards

Charles Moore