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New Member

Output drops Cisco interface

Hello,

on my Cisco WS-C2960-48TC-S i have 82933027 output drops on the access interface.

this interface is connected to only one computer, does someone have an idea how this is posible ??

 

L2_HHP-21#sh int fa0/12
FastEthernet0/12 is up, line protocol is up (connected) 
  Hardware is Fast Ethernet, address is d4a0.2a6c.6236 (bia d4a0.2a6c.6236)
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, 
     reliability 255/255, txload 2/255, 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 never, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 82933027
  Queueing strategy: fifo
  Output queue: 0/0 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 997000 bits/sec, 202 packets/sec
     161016 packets input, 20059528 bytes, 0 no buffer
     Received 12237 broadcasts (8646 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 8646 multicast, 0 pause input
     0 input packets with dribble condition detected
     90278417 packets output, 25066682913 bytes, 0 underruns
     0 output errors, 0 collisions, 1 interface resets
     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

 

Switch#sh run int fa0/12
Building configuration...

Current configuration : 168 bytes
!
interface FastEthernet0/12
 switchport access vlan 30
 switchport mode access
 switchport voice vlan 244
 spanning-tree portfast
 spanning-tree bpduguard enable
end

 

L2_HHP-21#sh mac add int fa0/12
          Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
  30    0010.f32e.6236    DYNAMIC     Fa0/12
Total Mac Addresses for this criterion: 1

 

8 REPLIES
Super Bronze

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Posting


Generally it's caused by sending packets to the interface faster than they can egress the interface.

 

On some switches, I think the 2960 being one of them, QoS being enabled on the switch, in a default configuration, often results in premature packet dropping due to default buffer reservations for QoS egress queues.

New Member

Hello joseph thank you for

Hello joseph thank you for your answer.

I have checked the global configuration but no QOS settings are enabled.

The output drops are not really high but i still have them.

This morning i reset the counters and now i have again "output drops: 2956"

it is just an interface connected to a computer so it is strange that it has the output drops.

 

FastEthernet0/2 is up, line protocol is up (connected)
  Hardware is Fast Ethernet, address is a456.308c.3102 (bia a456.308c.3102)
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 12/255, 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 never, output 00:00:00, output hang never
  Last clearing of "show interface" counters 05:19:54
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 2956
  Queueing strategy: fifo
  Output queue: 0/0 (size/max)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 4829000 bits/sec, 861 packets/sec
     10314 packets input, 1015389 bytes, 0 no buffer
     Received 1674 broadcasts (1373 multicasts)

Fa0/2                        connected    30         a-full  a-100 10/100BaseTX

 

sh mac add int fa0/2
          Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
  30    0010.f325.e554    DYNAMIC     Fa0/2
Total Mac Addresses for this criterion: 1

 

 

 

Super Bronze

What's the output packet

What's the output packet count (that corresponds to your drop count)?

New Member

could you explain a little

could you explain a little bit more, where can i find the output count ?

Hall of Fame Super Gold

There are several bugs I've

There are several bugs I've read where the output drops are "cosmetic". Can you specify what IOS you are running?
New Member

Hello Leo thank you for your

Hello Leo thank you for your answer.

The iios version is: c2960-lanlitek9-mz.122-50.SE5.bin

Hall of Fame Super Gold

Michael,  Upgrade your IOS to

Michael, 

 

Upgrade your IOS to 12.2(55)SE8.

New Member

the thing is, the output

the thing is, the output drops just occur sometimes. 

like now it did not have any additional output drops for 1 hour, the count stays at 2956 so it is sometimes.

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