08-08-2012 04:05 AM - edited 03-07-2019 08:13 AM
Hi All,
We have just enabled "mls qos" and executed default mls qos values.
Can you please explain me in simple words ,what it does ?
Thanks
Sri
Solved! Go to Solution.
08-08-2012 04:23 AM
COS stands for "class of service" and is l2 only. COS values are from 0 - 7 with 0 being low priority and 7 being high priority. Generally, phones will mark with cos 5 or a dscp value of 46 (EF). There is a cos-dscp mapping that happens outbound on the switch when it sends to the router for the router to see the dscp value that was converted from the internal map on the switch. Once your traffic is tagged at ingress (on switchport), the tag is carried to the output queue on the switch which leads to the router.
Here's something to read:
QoS is a very big topic...
08-08-2012 04:14 AM
It enables qos globally on the switch across all ports. By default, the switch will mark everything with cos 0.
HTH,
John
08-08-2012 04:17 AM
Thanks john for your quicky reply..
COS is L2 QOS, what is L2 QOS.. please explain me in a short ?
Thanks
Sri
08-08-2012 04:23 AM
COS stands for "class of service" and is l2 only. COS values are from 0 - 7 with 0 being low priority and 7 being high priority. Generally, phones will mark with cos 5 or a dscp value of 46 (EF). There is a cos-dscp mapping that happens outbound on the switch when it sends to the router for the router to see the dscp value that was converted from the internal map on the switch. Once your traffic is tagged at ingress (on switchport), the tag is carried to the output queue on the switch which leads to the router.
Here's something to read:
QoS is a very big topic...
08-08-2012 04:32 AM
Hi John,
Thanks for your info.. Got it what i am looking for :-)
08-08-2012 05:29 AM
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
Just want to mention . . .
L2 CoS requires VLAN tags to provide the CoS field between devices.
L3 ToS is part of every IP packet header. DSCP is the current recommendation for using the first 6 bits of the ToS byte.
Some "modern" L2 intelligent/smart switches support examination of L3 ToS.
The term CoS might also be use generically or for internal switch QoS treatment (on some Cisco switches).
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide