QoS question

[marcelnjkoks]

Hi, i have been reading up on QoS on Cat3750's, and there is something i do not understand from this section:

http://www.cisco.com/en/US/customer/products/hw/switches/ps5023/products_tech_note09186a0080883f9e.shtml#def-config

Where does the 4% absolute come from on queue1?  Does it have something to do with the fact that by default all egress queues have 25% of the bandwidth available, but queue 1 has a 25% shaped weight (others have 0)?

And what effect has the priority-queue output command on this?

Thanks!

[Lei Tian · Accepted solution]

Hi,

Once qos is enabled, queue 1 will be shaped to 4% by the default srr-queue bandwidth shape 25 0 0 0config on all interfaces. This 25 is not a percentage, it is 1/25. If priority-queue out is configured on the interface, all the shape or share weight applied to queue 1 will be ignored. Traffic in queue 1 will receive strict priority, and be served first over all other queues.

HTH,

Lei Tian

[marcelnjkoks]

Hi Lei Tian,

Thanx, this completely clears it up for me. The documentation is not to clear about this.

Very helpful!

[Lei Tian]

You are welcome! Thanks for the great rating!

Cheers,

Lei Tian