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Beginner

sh int counters errors

Hi All, 

 

I am seeing this "Outdiscards" on all the interfaces of 2960-X Switch.. Could someone point me in the right direction so I know how to fix them? I run a simple router-on-a-stick topo with dot1x, QoS and rspvt+  enable on all the ports/vlans.  

OFF-SW01#sh int counters errors

Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize OutDiscards
Gi1/0/1 0 0 1 0 0 347443
Gi1/0/2 0 0 1 0 0 246623
Gi1/0/3 0 0 0 0 0 21592
Gi1/0/4 0 0 1 0 0 523678
Gi1/0/5 0 0 1 0 0 200460
Gi1/0/6 0 0 0 0 0 179933
Gi1/0/7 0 0 1 0 0 215674
Gi1/0/8 0 0 1 0 0 513777
Gi1/0/9 0 0 1 0 0 511430
Gi1/0/10 0 0 0 0 0 0

 

 

interface GigabitEthernet1/0/1
description End User Port
switchport access vlan 56

witchport mode access
switchport voice vlan 32
ip access-group ACL-DEFAULT in
logging event trunk-status
srr-queue bandwidth share 1 30 35 5
priority-queue out
authentication event fail action next-method
authentication event server alive action reinitialize
authentication host-mode multi-auth
authentication open
authentication order dot1x mab
authentication priority dot1x mab
authentication port-control auto
mab
snmp trap mac-notification change added
mls qos trust device cisco-phone
mls qos trust cos
dot1x pae authenticator
dot1x timeout tx-period 6
flowcontrol receive desired
spanning-tree portfast edge
end

 

6 REPLIES 6
Beginner

Re: sh int counters errors

Hello,

It is likely your QoS scheduler is dropping egress packets.

We need to determine which queue is dropping, what is the related setting and which cos/dscp packets are guilty. Please output the following commands:

sh mls qos int gi1/0/1 stat | beg drop

sh mls qos int gi1/0/1 queueing

sh mls qos queue-set

sh mls qos map | beg outputq-threshold

 

Remi Astruc

Beginner

Re: sh int counters errors

Remi. 

 

Thanks for this input, I have attached the file with the requested output 

Beginner

Re: sh int counters errors

Hello,

So you probably have bursts from default traffic with COS and/or DSCP 0.

Assuming the default traffic is well assigned to the expected queue/threshold as designed, you can try to raise the SRR bandwidth for the affected queue 3 (queue 4 is also slightly concerned):

srr-queue bandwidth share 1 30 60 9

And increase the related buffers to absorb the peaks:

mls qos queue-set output 1 buffers 5 20 50 25

Then clear all the counters and see if drops decrease.

 

Remi Astruc

 

Hall of Fame Community Legend

Re: sh int counters errors

Turn off QoS.
Beginner

Re: sh int counters errors

I added the srr-queue shared and srr-queue shaped weights on the interfaces but still seeing some discard. from my little understanding of QoS, I think the traffic with COS 0 / dscp 0  (which is the most part of the traffic) goes into the queue 3 threshold 3. Now I don't know the best way to configure the cos-map. Any input on that?

 

 

mls qos map cos-dscp 0 8 16 24 32 46 48 56
mls qos srr-queue output cos-map queue 1 threshold 3 4 5
mls qos srr-queue output cos-map queue 2 threshold 1 2
mls qos srr-queue output cos-map queue 2 threshold 2 3
mls qos srr-queue output cos-map queue 2 threshold 3 6 7
mls qos srr-queue output cos-map queue 3 threshold 3 0
mls qos srr-queue output cos-map queue 4 threshold 3 1
mls qos srr-queue output dscp-map queue 1 threshold 3 32 33 40 41 42 43 44 45
mls qos srr-queue output dscp-map queue 1 threshold 3 46 47
mls qos srr-queue output dscp-map queue 2 threshold 1 16 17 18 19 20 21 22 23
mls qos srr-queue output dscp-map queue 2 threshold 1 26 27 28 29 30 31 34 35
mls qos srr-queue output dscp-map queue 2 threshold 1 36 37 38 39
mls qos srr-queue output dscp-map queue 2 threshold 2 24
mls qos srr-queue output dscp-map queue 2 threshold 3 48 49 50 51 52 53 54 55
mls qos srr-queue output dscp-map queue 2 threshold 3 56 57 58 59 60 61 62 63
mls qos srr-queue output dscp-map queue 3 threshold 3 0 1 2 3 4 5 6 7
mls qos srr-queue output dscp-map queue 4 threshold 1 8 9 11 13 15
mls qos srr-queue output dscp-map queue 4 threshold 2 10 12 14
mls qos queue-set output 1 threshold 1 100 100 100 100
mls qos queue-set output 1 threshold 2 100 100 100 400
mls qos queue-set output 1 threshold 3 100 100 100 400
mls qos queue-set output 1 threshold 4 100 100 100 400
mls qos queue-set output 2 threshold 3 3100 3100 100 3100
mls qos queue-set output 1 buffers 5 20 40 35
mls qos queue-set output 2 buffers 5 15 50 30
mls qos

Beginner

Re: sh int counters errors

Hi,

 

No, setting the shape weights override the share configuration and behaves the opposite way. Please remove shape statement if just added.

Also you have not set the queue-set buffers like suggested above.

 

Ensure to have the following on int g1/0/1 for example (without any "shape" command):

srr-queue bandwidth share 1 30 60 9

And in global, increase the related buffers to absorb the peaks:

mls qos queue-set output 1 buffers 5 20 50 25

According to your previous output, you should also raise threshold 1 of queue 4:

mls qos queue-set output 1 threshold 4 100 100 100 400

Then clear counters and check the values.

clear counters

clear mls qos interface statistics

You will surely see improvements.

 

Remi Astruc

 

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