Output Drops in Cisco 2960

[Sgj]

Hello,

I found Output Drops in some Interfaces in Cisco 2960 series and want to solve this.

But when trying to type the command 'qos queue-softmax-multiplier 1200' , it doesn't work.

I already try this command in other series, it works.

Does anybody know the correct command of 'qos queue-softmax-multiplier 1200' in the 2960 series?

Thanks in advanced

[balaji.bandi]

But when trying to type the command 'qos queue-softmax-multiplier 1200' , it doesn't work.

I already try this command in other series, it works.

when you mention other series what is the model and IOS, what is the IOS version of 2960 here ?

[Sgj]

In 9200 and 3650 series

[Georg Pauwen]

Hello,

an alternative to the softmax settings (since they are not available, and if they were, do not always eliminate output drops) would be to do some interface buffer tuning. For that, post the output of (provided you have 'mls qos' enabled globally}:

2960(config)#mls qos

!

2960#show mls qos maps dscp-output-q

2960#show mls qos queue-set

You could also try and disable 'mls qos' altogether, if you have it enabled, that sometimes reduces or eliminates the output drops.

And last but not least, you could try some generic queue tuning:

mls qos

!

mls qos queue-set output 1 threshold 1 3200 3200 25 3200
mls qos queue-set output 1 threshold 2 3200 3200 25 3200
mls qos queue-set output 1 threshold 3 3200 3200 25 3200
mls qos queue-set output 1 threshold 4 3200 3200 25 3200

[Sgj]

Thanks for the reply,

Here's the information :

 

[Georg Pauwen]

Hello,

sorry, my bad, I also need the output of:

show mls qos interface gix/x statistics

of the interface where the output drops are occuring. 

[Sgj]

Hello,

There are 2 interfaces where the output drops, Fa0/14 & Fa0/24.

There's already a command with 'mls qos queue-set output 1 threshold . . .',

Do I have to replace it with,

mls qos queue-set output 1 threshold 1 3200 3200 25 3200
mls qos queue-set output 1 threshold 2 3200 3200 25 3200
mls qos queue-set output 1 threshold 3 3200 3200 25 3200
mls qos queue-set output 1 threshold 4 3200 3200 25 3200

for options other than command 'qos queue-softmax-multiplier 1200'?

Thanks in advanced

[Georg Pauwen]

Hello,

post the output of:

show mls qos interface FastEthernet0/14 statistics

show mls qos interface FastEthernet0/24 statistics

The values:

mls qos queue-set output 1 threshold 1 3200 3200 25 3200
mls qos queue-set output 1 threshold 2 3200 3200 25 3200
mls qos queue-set output 1 threshold 3 3200 3200 25 3200
mls qos queue-set output 1 threshold 4 3200 3200 25 3200

are generic, you might try them and monitor if the output drops decrease.

[Sgj]

Here's the output from :

- Fa0/14

- Fa0/24

[Georg Pauwen]

Hello,

ok, my calculation has come up with the below. Configure this globally:

AS02-3(config)#mls qos queue-set output 2 threshold 3 3100 3100 100 3200

and this under your interfaces:

interface FastEthernet0/14
queue-set 2
!
interface FastEthernet0/24
queue-set 2

[Sgj]

Hello,

Okay, I've added the configuration as you said.

And I've also added a configuration like,

mls qos queue-set output 1 threshold 1 3200 3200 25 3200
mls qos queue-set output 1 threshold 2 3200 3200 25 3200
mls qos queue-set output 1 threshold 3 3200 3200 25 3200
mls qos queue-set output 1 threshold 4 3200 3200 25 3200

Thank you for your help.
I'll update again here after a few days of monitoring.

[Georg Pauwen]

Hello,

keep in mind that, if you apply the below:

mls qos queue-set output 1 threshold 1 3200 3200 25 3200
mls qos queue-set output 1 threshold 2 3200 3200 25 3200
mls qos queue-set output 1 threshold 3 3200 3200 25 3200
mls qos queue-set output 1 threshold 4 3200 3200 25 3200

it affects all ports on the entire switch (queue set 1). If you use what I proposed:

AS02-3(config)#mls qos queue-set output 2 threshold 3 3100 3100 100 3200

!

interface FastEthernet0/14
queue-set 2
!
interface FastEthernet0/24
queue-set 2

only the two ports are affected.

[Sgj]

Okay, I already set the 'mls qos queue-set output 1 threshold . . . . .' to default again.

Let see after for a few days.

Thank you for your information

[Georg Pauwen]

Curious to know the results. Keep us updated...

[Sgj]

Hello,

There's still a Drop packet,

AS02-3#sh int fa0/14
FastEthernet0/14 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is dc7b.94df.440e (bia dc7b.94df.440e)
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 4/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is 10/100BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:40, output 00:00:01, output hang never
Last clearing of "show interface" counters 3d15h
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 25981
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 349000 bits/sec, 344 packets/sec
5 minute output rate 1787000 bits/sec, 404 packets/sec
1734648 packets input, 249446073 bytes, 0 no buffer
Received 399255 broadcasts (296169 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 296169 multicast, 0 pause input
0 input packets with dribble condition detected
1787816 packets output, 553201068 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out

AS02-3#sh int fa0/24
FastEthernet0/24 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is dc7b.94df.4418 (bia dc7b.94df.4418)
MTU 1500 bytes, BW 100000 Kbit/sec, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is 10/100BaseTX
input flow-control is off, output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:32, output 00:00:00, output hang never
Last clearing of "show interface" counters 3d15h
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 4482
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 27000 bits/sec, 8 packets/sec
5 minute output rate 58000 bits/sec, 15 packets/sec
617103 packets input, 84796619 bytes, 0 no buffer
Received 93908 broadcasts (24643 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 24643 multicast, 0 pause input
0 input packets with dribble condition detected
1821075 packets output, 382143080 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 babbles, 0 late collision, 0 deferred
0 lost carrier, 0 no carrier, 0 pause output
0 output buffer failures, 0 output buffers swapped out