Friday, November 1, 2013

Cisco Switch QoS: 12.2(40) IOS And 'auto qos' Thoughts

I have run into this a lot in the past, where I come across a switch/router that doesnt have QoS configured correctly.  Sometimes its not a big deal, but sometimes it is.  I came across a few switch configs that did not have the "priority-queue out" command where phones resided and on the uplinks.  Here is an example of what I saw:
interface FastEthernet0/2
 description Host/IP Phone
 switchport access vlan 2
 switchport mode access
 switchport voice vlan 3
 srr-queue bandwidth share 10 10 60 20
 srr-queue bandwidth shape  10  0  0  0 
 mls qos trust device cisco-phone
 mls qos trust cos
 macro description cisco-phone
 auto qos voip cisco-phone 
 spanning-tree portfast
 spanning-tree bpduguard enable

They had done the 'auto qos' command, probably thinking this would be enough.  However, the version of code was 12.2(35) on this 3560 switch.  What they probably didn't know was that in the code prior to version 12.2(40), the 'priority-queue out' command does not get implemented with auto qos.  You have to manually go and put that in.   And you need that command in there so that you have a true priority que.   Always check QoS when coming behind someone. 

1 comment:

  1. Thanks Shane!! Good catch. (Not that I would forget this, or, not me. Oops...)


Your comment will be reviewed for approval. Thank you for submitting your comments.