[cisco-bba] High TCP packet loss over ATM

James Wakefield jamesw at deakin.edu.au
Mon Nov 6 17:02:02 EST 2006

Mark wrote:
> After a bit of research i found that rx_cell_loss are increasing quickly.
> What this means?
> rgds
> mark

It could mean a few things...can you paste the full output of a show atm 
  vc and a show atm controller for the VC in question?

My instinct is to suspect a mismatch in ATM QoS parameters between your 
end and the ATM provider, probably because I've experienced that before. 
  If you're getting cell loss on the rx side, your VC's QoS may be 
configured for rates lower than your ATM provider has configured, 
meaning they're bursting faster and/or for longer than your interface 
will accept, and your interface is marking them for discard by setting 
CLP.  Physical problems such as cable damage or dirty connectors etc. 
are probably not going to be it as your OAM pings are working.  It's 
possible you're running out of buffers/queue slots, you could try 
increasing your rx queue in that case.  Other than that, it could be a 
buggy controller or IOS, which you should be able to search cisco.com for.

James Wakefield,
Unix Administrator, Information Technology Services Division
Deakin University, Geelong, Victoria 3217 Australia.

Phone: 03 5227 8690 International: +61 3 5227 8690
Fax:   03 5227 8866 International: +61 3 5227 8866
E-mail:   james.wakefield at deakin.edu.au
Website:  http://www.deakin.edu.au

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