Slow network catalyst 6500

Unanswered Question
Aug 2nd, 2007


I have a problem on a network with slow FTP transfer and backup file share.

When I run a backup on a file share server directly connected to the 6500 the transfer bandwith do not exceed 40kb/s.

When I test a FTP transfer between two pc connected to the catalyst 6500 and in the same vlan, the bandwith is about 100kb/s. The same test with two pc in different vlan leads to the result.

No access-list is configure to the catalyst 6500, the process cpu is less than 2%.

The Catalyst 6500 is in native IOS 12.1-(8b)E19 SUP1A-2G MSFC2.

How can I troubleshoot the problem.

Have you any idea about this problem ?

We have checked about all error counters, all speed an duplex.

Thanks in advance


I have this problem too.
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Loading. Thu, 08/02/2007 - 01:00

Are you using the same FTP server in both your tests. Is it exactly 40kb/s or does it fluctuate? If its exactly, it sounds like the FTP server could be throttling the connection, or some LAN management software on the FTP server.

michal.grzelak Thu, 08/02/2007 - 01:40


Please try to do sniffer and look into packets for packets lenght, TCP window. Moreover what type of FTP mode are You using active or passive.

Please also look at results of show int gi x/x switching (hidden command) to see how packets are switched, either by RP or SP.



glen.grant Thu, 08/02/2007 - 03:46

It is possible you have an oversubscription issue if you have numerous servers on the same card , you might try moving the server port to a different card and see what happens . CPU has very little to do with transfer rates as most traffic is switched in hardware and never sees the CPU on the MSFC .


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