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Can you see anything wrong with my output drops?

Chris Golden
Level 1
Level 1

Hi there, could someone with an expert eye tell me if you see something wrong on this interface summary.  I notice a lot of output drops?

 

GigabitEthernet1/0/40 is up, line protocol is up (connected) 
  Hardware is Gigabit Ethernet, address is 2834.a2fc.f5a8 (bia 2834.a2fc.f5a8)
  Description: UPLINK-FROM-SW1AN
  MTU 9014 bytes, BW 1000000 Kbit/sec, DLY 10 usec, 
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, media type is 10/100/1000BaseTX
  input flow-control is off, output flow-control is unsupported 
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:03, output never, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 64577934
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 1311000 bits/sec, 212 packets/sec
  5 minute output rate 1861000 bits/sec, 296 packets/sec
     1690456673 packets input, 1243471503312 bytes, 0 no buffer
     Received 37922813 broadcasts (6164559 multicasts)
     0 runts, 0 giants, 0 throttles 
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 6164559 multicast, 0 pause input
     0 input packets with dribble condition detected
     1747198376 packets output, 1436286894560 bytes, 0 underruns
     64577934 output errors, 0 collisions, 1 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
8 Replies 8

Julio E. Moisa
VIP Alumni
VIP Alumni

Hi

Try clearing the counters and verify if the output errors are increasing again. You could change the cable or move it to other port and see the behavior.




>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<

 

Current configuration : 143 bytes
!
interface GigabitEthernet1/0/6
 description WINNODE1-iSCSI
 switchport access vlan 1035
 switchport mode access
 spanning-tree portfast
end

SWRTSR(config)#do sh run int gi2/0/6
Building configuration...

Current configuration : 143 bytes
!
interface GigabitEthernet2/0/6
 description WINNODE1-iSCSI
 switchport access vlan 1038
 switchport mode access
 spanning-tree portfast
end

SWRTSR(config)#do sh int gig1/0/6 | inc output drop              
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 42826285
SWRTSR(config)#do sh int gig2/0/6 | inc output drop
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 44942947

IBMeR
Level 1
Level 1

Hello,

Output errors in most cases you may see if you have drops output traffic - for example, in time interface overflow or qos policy drops.

I can't say more exactly - it's platform-dependent. What equipment model is it?

P.S. You may compare drops count with this string your output:

Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 64577934

Hi its a WS-C3850-48T

This document explains this problem for this platform. You can find case study around end of document:

https://www.cisco.com/c/en/us/support/docs/switches/catalyst-3850-series-switches/200594-Catalyst-3850-Troubleshooting-Output-dr.html

So I reset the counters and the problem is still there:

 

5 minute output rate 107724000 bits/sec, 11341 packets/sec
     732038946 packets input, 1039418203867 bytes, 0 no buffer
     Received 979480 broadcasts (877032 multicasts)
     0 runts, 0 giants, 0 throttles 
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 877032 multicast, 0 pause input
     0 input packets with dribble condition detected
     248494333 packets output, 207704499465 bytes, 0 underruns
     6217516 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

I increased the qos queue-softmax-multiplier to 200 and now presently I do not see any drops other than these two interfaces:

 

Current configuration : 143 bytes
!
interface GigabitEthernet1/0/6
 description WINNODE1-iSCSI
 switchport access vlan 1035
 switchport mode access
 spanning-tree portfast
end

SWRTSR(config)#do sh run int gi2/0/6
Building configuration...

Current configuration : 143 bytes
!
interface GigabitEthernet2/0/6
 description WINNODE1-iSCSI
 switchport access vlan 1038
 switchport mode access
 spanning-tree portfast
end

SWRTSR(config)#do sh int gig1/0/6 | inc output drop              
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 42826285
SWRTSR(config)#do sh int gig2/0/6 | inc output drop
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 44942947

I increased the qos queue-softmax-multiplier to 200 and now presently I do not see any drops other than these two interfaces:

 

Current configuration : 143 bytes
!
interface GigabitEthernet1/0/6
 description WINNODE1-iSCSI
 switchport access vlan 1035
 switchport mode access
 spanning-tree portfast
end

SWRTSR(config)#do sh run int gi2/0/6
Building configuration...

Current configuration : 143 bytes
!
interface GigabitEthernet2/0/6
 description WINNODE1-iSCSI
 switchport access vlan 1038
 switchport mode access
 spanning-tree portfast
end

SWRTSR(config)#do sh int gig1/0/6 | inc output drop              
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 42826285
SWRTSR(config)#do sh int gig2/0/6 | inc output drop
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 44942947