Output Queue Drops on Cisco 7204VXR (NPE-G2)

mohammedn1 · ‎07-07-2015

Hello All,

We have a 7200 router in my network which links two major sites . The problem we face is, the wan interface keeps throwing Output errors.

This link is 300 MB link and only 15% usage is observed all the time.

Fastswitching is enabled.

interface GigabitEthernet0/1
description 300 Mb PPOE HR-R
bandwidth 300000
ip address 10.xx.xx.xx 255.255.255.252
ip flow ingress
ip pim sparse-dense-mode
duplex full
speed 1000
media-type gbic
no negotiation auto
service-policy output 300Mb-TRSH-MAP
end
!
BR2-WAN#sh int gi0/1 switching
GigabitEthernet0/1 300 Mb PPOE HR-R
Throttle count 18
Drops RP 15059993 SP 0
SPD Flushes Fast 1019 SSE 0
SPD Aggress Fast 0
SPD Priority Inputs 135410121 Drops 0

Protocol IP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 1292792339 1019182252 153009930 823178344
Cache misses 1 - - -
Fast 2239422050 1998293806 1840386780 2475637248
Auton/SSE 0 0 0 0

Protocol DEC MOP
Switching path Pkts In Chars In Pkts Out Chars Out
Process 0 0 99250 7642250
Cache misses 0 - - -
Fast 0 0 0 0
Auton/SSE 0 0 0 0

BR2-WAN#sh int gi0/1 summ

*: interface is up
IHQ: pkts in input hold queue IQD: pkts dropped from input queue
OHQ: pkts in output hold queue OQD: pkts dropped from output queue
RXBS: rx rate (bits/sec) RXPS: rx rate (pkts/sec)
TXBS: tx rate (bits/sec) TXPS: tx rate (pkts/sec)
TRTL: throttle count

Interface IHQ IQD OHQ OQD RXBS RXPS TXBS TXPS TRTL
------------------------------------------------------------------------
* GigabitEthernet0/1 0 352337 0 112553 59273000 14207 29426000 12343 5

Please let me know what is the problem with it. Thanks in advance.

Vinit Jain · ‎07-07-2015

Hello,

most of the time when there are output Q drops, its because of the service-policy. Could you please share the below commands:

- show int gi 0/1

- show policy-map int gi 0/1 output

- show int gi 0/1 switching

Capture the above output 2-3 times and share it in a file. i see a lot of packets getting process switched as well. It would be interesting to see why packets are getting process switched.

Once i have the logs will look into the issue.

Thanks,

Vinit

Thanks
--Vinit

mohammedn1 · ‎07-13-2015

Thanks for responding. Please find the ouputs attached.

The above link is 500 MB,not 300. Description was not updated

Joseph W. Doherty · ‎07-13-2015

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

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In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Your stats show the shaper has delayed packets and about 14% of your drops are no-buffer. Both would imply your 15% utilization might not always be true.

Joseph W. Doherty · ‎07-13-2015

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

Posting the policy would be helpful, as for 300 Mbps, a service policy's default buffers might be too small. Regarding the 15% utilization, you could still have microburst causing drops, while overall utilization is low and/or the low utilization might be because of a high drop rate.