[c-nsp] 7500 queue question

[Rodney Dunn]

What is the depth of the controller txring in 'sh contr'?

I can't remember if the output hold queue is inclusive of packets that
have already been placed on the txring of the interface to go out.
I would think it is conclusive.

You have to understand your traffig generator and how it generates
burst also. ie: what is the inter-packet gap.

Another thing that is complicated is the servicing
of rx and tx rings and how a few packets will sit on the rx rings until
the interrupt service routine gets a chance to do the lookup to move
it to the tx side.

 


On Mon, Jun 20, 2005 at 09:56:28AM -0400, Rik Koenig wrote:
> Hello all,
> 
>  
> 
> Last week we were playing around with output queue depths and packet loss.
> Running a 7507 with RSP4, and VIP2-50 (128/8), and PA-FE-TX and PA-4E. Using
> the 100Mb Ethernet as input and the 10Mb as output. CEF is running, but not
> dCEF. 
> 
>  
> 
> We would burst a given number of 224B frames into the 100Mb port, to exit
> the 10Mb port. Given the 40-deep FIFO exit queue, we needed to burst 170
> packets before any were dropped! When we dropped the queue down to 5 or 1,
> we needed 40 or so. 
> 
>  
> 
> Now, to my thinking, if a 100Mb link is receiving 41 packets, a 10Mb link
> that reports it can hold 40 packets should back up and tail-drop. But this
> didn't happen. What am I missing?
> 
>  
> 
> Thanks,
> 
> ~Rik
> 

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