Warning message

  • Cisco Support Forums is in Read Only mode while the site is being migrated.
  • Cisco Support Forums is in Read Only mode while the site is being migrated.

TCP Optimization on a fast link

Unanswered Question
Aug 18th, 2003
User Badges:


we're experiencing poor TCP performance on a Oc3 link because of high delay.(20ms)

The delay is because of length of the line.

I know that I can change the TCP window size to optimize the performance but I would have to do this on several hundreds PCs.

Does anybody know a better way to improve the performance? (e.g. some kind of magic blackbox which adapts the TCP window size)



  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
deilert Mon, 08/18/2003 - 05:13
User Badges:
  • Silver, 250 points or more

If you are experiencing poor performance with 20 ms response time , I would not start playing with the TCP window size, 20 ms response is excellent response time , I would have the application and server support start looking a little harder at there piece os the pie, this sounds like a classic exapmle of the application /server guys not knowing how to fix there problem and blaming the network .

To further support your case you can sniff the wire to determine what is causing the poor performance .

Good Luck

t.baranski Mon, 08/18/2003 - 17:25
User Badges:
  • Bronze, 100 points or more

20ms isn't bad for a WAN but with a default maximum TCP window size of 64KB, you're limited to ~24mbits/sec per flow if my calculations are correct. I'm not aware of a device that can adjust TCP window values in existing TCP sessions -- offhand, the practicality of such a device seems questionable at best.


This Discussion