Question : Cisco:  output buffer failures

Hi gurus

I have something odd in my Cisco switch

(Cisco Internetwork Operating System Software
IOS (tm) C3500XL Software (C3500XL-C3H2S-M), Version 12.0(5)WC13, RELEASE SOFTWARE (fc1)
Copyright (c) 1986-2005 by cisco Systems, Inc.
Compiled Tue 20-Sep-05 10:05 by antonino
Image text-base: 0x00003000, data-base: 0x00351FFC

ROM: Bootstrap program is C3500XL boot loader

Uutiset uptime is 4 weeks, 5 days, 9 hours, 37 minutes
System returned to ROM by power-on
System restarted at 02:05:55 UTC Thu Oct 19 2006
System image file is "flash:c3500xl-c3h2s-mz.120-5.WC13.bin"
)


I have "output buffer failures" in several interfaces. Here is one:


FastEthernet0/45 is up, line protocol is up
  Hardware is Fast Ethernet, address is 0001.426f.562d (bia 0001.426f.562d)
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive not set
  Full-duplex, Auto Speed (100), 100BaseTX/FX
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input never, output 00:00:00, output hang never
  Last clearing of "show interface" counters 19:22:09
  Queueing strategy: fifo
  Output queue 0/40, 0 drops; input queue 0/75, 0 drops
  5 minute input rate 1000 bits/sec, 0 packets/sec
  5 minute output rate 4000 bits/sec, 6 packets/sec
     40331 packets input, 6677452 bytes
     Received 309 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast
     0 input packets with dribble condition detected
     256860 packets output, 47928385 bytes, 286 underruns                                        | 286 underruns !!!!!
     0 output errors, 0 collisions, 0 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier
     286 output buffer failures, 0 output buffers swapped out                                        | 286 output buffer failures !!!!              




Now I really would like to get hints that what causing these errors ? What I should check next ?

Thanks for any help.

-Jussi

Answer : Cisco:  output buffer failures

Hi,
I ran this through Cisco's "Output Interpretter" for you.




Interface FastEthernet0/45 (up/up)
  WARNING: Interface FastEthernet0/45 is up/up but keepalives are not set (set
  to 0 secs) so the interface could be spoofing. Spoofing means the interface appears
  up to higher layers so that packets can be routed to it, such as a DDR interface.
  TRY THIS: Set the keepalive timer to an integer value using the 'keepalive' interface
  configuration command. The default is 10 secs.
 
  INFO: The CRC erros found on the interface are less than 0.0001% of the total
  input packets and can be ignored.
 
  INFO: There have been 286 'output buffer failures' reported.
  If outgoing interface buffers are not available, an output buffer failure is reported.
  If an interface buffer is available but the Transmit Queue Limit is reached,
  the packet is dropped. However, if 'transmit-buffers backing-store' is enabled,
  the packet is placed in a System Buffer (which has to be obtained from an appropriate
  Free-List), and enqueued in the Output Hold queue for future transmission at
  the Process level, and an Output Buffer Swap is reported.
 
  WARNING: 286 underruns have been reported, which amounts to 0.11122% of the
  total input traffic. This is because, the far-end transmitter runs faster than
  the receiver of the near-end router can handle.
  TRY THIS: This problem can occur because the router is not powerful enough, and/or
  the interface is running at a slower speed. Analyze traffic patterns to determine
  the source of large amount of traffic received by the interface. However, this
  may not be possible because, these counters could have been incremented at some
  point in the past. Consider pasting the 'show buffer' command output into Output
  Interpreter to see if the buffers can be tuned.
  REFERENCE: For more information, see Performance Tuning Basics
 
  INFO: The last input for this interface is 'never' and the 'packets input' counter
  is greater than 0. The counters contradict each other. This is because the last
  input counter only gets timestamped when the CPU has to process an input packet.
  This does not get updated when network traffic is simply forwarded in hardware,
  without the CPU touching it. Most likely this output is from a switch interface
  or this interface supports some form of switching, such as fast, autonomous,
  silicon, netflow, etc.