Saturday, December 21, 2013

QOS Troubleshooting on 6500/3750/2900/4500


DSCP TOS CoS Precedence conversion


Need to be updated.


QOS on 4500


Show platform hardware qos interface<> tx-queue

show policy-map interface <>



QOS on SUP720


show mls qos int gig <> statistics    -------->  Does not work on SUP720 .

ip access-group on layer 2    ------->    Does not work on SUP720 trunk interface as well.



QOS on SUP2T


By default ,its trust DSCP , Checked and verified in the lab with SUP2T.

Port QOS is disabled on interface if "auto qos default " disabled.

Show queueing interface teng1//1  or gig interface on SUP2T




QOS on 2960/3750

 Show mls qos int gig1/0 statistics--------> To check the incoming/outgoing dscp marking and drops and enqued

Show mls qos queuse-set 1 or 2

clear mls qos interface gig1/0 statiscts-----> To clear the mls qos statistics used this command.


mls qos queueu-set output 1 buffer  5 10 80 5

mls qos queueuset- threshold 100 100 100 400 ……….>   Two ways to give more buffer 1) assign buffers from others queue or move the  the threshold  to correct level or increase reserved threshold value  or increase the maximum percentage and then adjust the threshold value

make sure to check cos and dscp queue for correct  threshold mapping .

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