difference between Total output drop and Queue Output drop

Tomasz Tuzimek · ‎05-21-2010

Who know what is difference between both values and when counters are increment.

show interface gig0/1

...

Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/26/0 (size/max/drops/flushes); Total output drops: 151329
Queueing strategy: Class-based queueing
Output queue: 0/1000/0 (size/max total/drops)

...

I read most documentations and troubleshootings (for example "In/Out queue drop", "buffer tuning") but there is poorly description.

--

Tom

Ganesh Hariharan · ‎05-21-2010

Who know what is difference between both values and when counters are increment.

show interface gig0/1

...

Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/26/0 (size/max/drops/flushes); Total output drops: 151329
Queueing strategy: Class-based queueing
Output queue: 0/1000/0 (size/max total/drops)

...

I read most documentations and troubleshootings (for example "In/Out queue drop", "buffer tuning") but there is poorly description.

--

Tom

Hi Tom,

Output drops are the result of a congested interface (for example, the traffic rate on the outgoing interface can't accept all packets that should be sent out). The ultimate solution to resolve the problem is to increase the line speed.

Check out the below link for more information

http://www.frameip.com/dos-cisco/queue_drops.pdf

Hope to Help !!

Ganesh.H

Remember to rate the helpful post

jsmetz · ‎12-17-2010

Hi Tom,

Better later than never

Total ouput drops is the sum of qdrops from 'show hqf interface' for latest IOS releases which include HQF framework (QoS Code Rewrite) starting with 12.4(20)T.

qdrops increase for a class when we have more packets than the queue-limit (available buffer in show hqf int) for the given class.

Output queue drops is the sum of qdrops + drops due to other features such as WRED, etc .

Cheers,

Jean

Tomasz Tuzimek · ‎12-19-2010

########################for CBWFQ

sh int gi 0/1

GigabitEthernet0/1 is up, line protocol is up
...

...

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 (sum hard-limit and soft-limit and other features)

Queueing strategy: Class-based queueing
Output queue: 0/1000/64/0 (size/max total(#hard-limit)/threshold(soft limits are set per queue so I don't know what is this? )/drops(only hard-limit drops))
     Conversations 0/1/256 (active/max active/max total)
     Reserved Conversations 3/3 (allocated/max allocated)
     Available Bandwidth 34984 kilobits/sec

I think that "Output queue" drops in "sh int gi 0/1" is the hard limit (hold-queue - default 1000 packets per interface)

The soft limit(queue-limit - default 64 packets per queue) is in the "sh policy-map interface gi0/1":

...

Class-map: NC (match-any)
      986 packets, 126198 bytes
      5 minute offered rate 1000 bps, drop rate 0 bps
      Match: ip precedence 6
        986 packets, 126198 bytes
        5 minute rate 1000 bps
      Match: ip precedence 7
        0 packets, 0 bytes
        5 minute rate 0 bps
      Queueing
        Output Queue: Conversation 265
        Bandwidth 16 (kbps)Max Threshold 64 (packets)
        (pkts matched/bytes matched) 193/54748
        (depth/total drops/no-buffer drops) 0/0/0    #soft limit (queue-limit) queue NC

Hold-queue(default1000) is hard limit (sum of all packets in all queues on interface) if sum packets on all queues of interface exceed hold-queue the interface will drop packets above that limit.