03-27-2019 08:21 AM
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
03-27-2019 09:50 AM
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
03-27-2019 01:40 PM
03-28-2019 01:24 AM
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
03-27-2019 11:00 PM
03-28-2019 09:49 AM
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
03-28-2019 02:38 PM
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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