[c-nsp] 7500 queue question

[Rodney Dunn]

if-con <slot>
sh controller

On Mon, Jun 20, 2005 at 11:41:31AM -0400, Rik Koenig wrote:
> I get no information on the e/fe interfaces using 'show contr'. I'm using 
> 12.2(21a).
> 
> Inter packet gap is 960ns. 
> 
> 
> -----Original Message-----
> From: Rodney Dunn [mailto:rodunn at cisco.com] 
> Sent: Monday, June 20, 2005 10:52 AM
> To: Rik Koenig
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] 7500 queue question
> 
> 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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