Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

CBWFQ, The priority command

Hi,

I am trying to get clear understanding of using the keyword priority in the voice class.  When the voice class has  "priority percent 30", does this mean that voice packets will be given 30% of the bandwidth only is link is congested, but if it needs more, it will never get it since the class will only get 30% max?

Also, if there is no voice packets, can other classes with the "bandwidth remaining percent xx" use the 30% that is available out of the voice class, or is 30% RESERVED and cannot be used by any other class?  I am ready conflicting info about the meaning of reserverd for the priority queue.

 

Here is the policy

policy-map PMap-WAN
 class CMap-Voice-WAN
  priority percent 20
 class CMap-Video-WAN
  priority percent 10
 class CMap-Signal-WAN
  bandwidth remaining percent 5
 class CMap-Critical-Mngt-WAN
  bandwidth remaining percent 25
  random-detect dscp-based
  service-policy Mark-BGP
 class CMap-Bulk-WAN
  bandwidth remaining percent 15
  random-detect dscp-based
  fair-queue
 class CMap-Default-WAN
  bandwidth remaining percent 25
  fair-queue
  queue-limit 128 packets
  random-detect

 

Thank you in advance!

1 REPLY
Super Bronze

DisclaimerThe Author of this

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

 

When the voice class has  "priority percent 30", does this mean that voice packets will be given 30% of the bandwidth only is link is congested, but if it needs more, it will never get it since the class will only get 30% max?

 

If there's congestion, such that packets queue in the LLQ class, a policer will engage, policing that LLQ to the specificed bandwidth usage.

 

If there's no queuing, the LLQ class can use more than the specified bandwidth limit.  (NB: Peter Paluch confirmed this for us, with lab testing, when a similar question arose in an earlier posting.)

 

Also, if there is no voice packets, can other classes with the "bandwidth remaining percent xx" use the 30% that is available out of the voice class, or is 30% RESERVED and cannot be used by any other class?

 

Other classes can use other classes unused bandwidth.  The "reservation" really is a minimum bandwidth guarantee when there's congestion.  It's not "reserved" in the sense that it's set aside for exlusive usage of a class.

36
Views
0
Helpful
1
Replies