Difference between TX ring and hold queue out under an interface.

[sarahr202]

Hi everybody,

I am just trying to wrap my head around this.

What is the difference between hold queue out  and tx ring?

I could not find  good documentation about it.  TX ring is hard ware queue of an interface, easy but what is hold queue out ?

http://blog.ine.com/2008/08/17/insights-on-cbwfq/#more-231

The above links says:

All flows share the buffer pool that system allocates to CBWFQ, using the hold-queue N out interface-level command where N is the number of buffers.

But the command shows it is length of the queue. 

R1(config-if)#hold-queue ?
<0-4096> Queue length

 what is it? is "hold-queue out" the amount of buffer allocated as per above link or is it queue length ? If it is queue length how is it different from tx ring length?

Thanks,

[Reza Sharifi · Accepted solution]

Hi Sarah,

Hope you are doing well..

I found a couple of resources that maybe useful to you.

Output hold-queue is software queue allocated by system memory .The output hold-queue, which can be tuned by "hold-queue x out" is actually only used for traffic processed by CPU

link:

https://supportforums.cisco.com/document/106806/output-drops-input-queue-drops-hold-queues

And here is a link to another community post from a few years ago.

https://supportforums.cisco.com/discussion/10903871/what-rx-ringtx-ring-router

HTH