[c-nsp] Interface Queues

[Ahmed Maged (amaged)]

The answer below doesn't fit for all platforms/interfaces but I hope it
helps.

 

In the case of 7200 and low-end, years ago: tx-queue-limit referred to
the "Fifo memory between the intelligent scheduler and the wire" 

 

That memory was too large for VoIP and caused too much jitter even with
PQ and so on.

 

 

As for hold-queue:

 

when packets are switched in IOs, there is an interface hold-queue that
will receive the packtes received from the interface.

 

every received packet generates an interrupt indicating it requires
service.

 

the interface ISR (interrupt service routine) will determine if this
packet is to be forwarded via cef, or locally destined or cannot be fast
switched and has to be process switched by IP INPUT.

 

Cheers,

Ahmed

 

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Ibrahim Abo Zaid
Sent: Saturday, July 26, 2008 6:06 PM
To: cisco-nsp at puck.nether.net; cisco at groupstudy.com
Subject: [c-nsp] Interface Queues

 

Hi All

 

i am a bit confused between Interface queues that can be configured
using

tx-queue-limit and hold-queue  , what is the difference between these
queues

?

 

 

appreciate your replies .

 

best regards

--Ibrahim

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