[c-nsp] Small Catalysts with odd "no buffer" errors

[Jeff Kell]

I have a 2950 switch we just provisioned to deploy, and in checking it
out beforehand, have run into an unusual "no buffers" condition.  I've
seen this before but never been able to resolve what is causing it.  See
if this rings any bells...

Doctors-Temp#sho int f0/1
FastEthernet0/1 is up, line protocol is up (connected)
  Hardware is Fast Ethernet, address is 0007.8436.5041 (bia 0007.8436.5041)
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s, media type is 100BaseTX
  input flow-control is unsupported output flow-control is unsupported
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:00, output 00:00:08, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 10000 bits/sec, 13 packets/sec
  5 minute output rate 0 bits/sec, 0 packets/sec
     36881 packets input, 3921937 bytes, *2443 no buffer*
     Received 33638 broadcasts (10590 multicast)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, *2443 ignored*
     0 watchdog, 10585 multicast, 0 pause input
     0 input packets with dribble condition detected
     15496 packets output, 1222739 bytes, 0 underruns
     0 output errors, 0 collisions, 2 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

There are no traditional buffer exceptions:

Doctors-Temp#show buffers
Buffer elements:
     499 in free list (500 max allowed)
     43707 hits, 0 misses, 0 created

Public buffer pools:
Small buffers, 104 bytes (total 60, permanent 25, peak 103 @ 01:33:34):
     60 in free list (20 min, 60 max allowed)
     19032 hits, 26 misses, 43 trims, 78 created
     0 failures (0 no memory)
Middle buffers, 600 bytes (total 30, permanent 15, peak 36 @ 01:33:35):
     28 in free list (10 min, 30 max allowed)
     8082 hits, 7 misses, 6 trims, 21 created
     0 failures (0 no memory)
Big buffers, 1524 bytes (total 7, permanent 5, peak 7 @ 01:33:19):
     7 in free list (5 min, 10 max allowed)
     182 hits, 1 misses, 0 trims, 2 created
     0 failures (0 no memory)
VeryBig buffers, 4520 bytes (total 2, permanent 0, peak 2 @ 00:44:36):
     2 in free list (0 min, 10 max allowed)
     143 hits, 1 misses, 0 trims, 2 created
     0 failures (0 no memory)
Large buffers, 5024 bytes (total 0, permanent 0):
     0 in free list (0 min, 5 max allowed)
     0 hits, 0 misses, 0 trims, 0 created
     0 failures (0 no memory)
Huge buffers, 18024 bytes (total 0, permanent 0):
     0 in free list (0 min, 2 max allowed)
     0 hits, 0 misses, 0 trims, 0 created
     0 failures (0 no memory)

Interface buffer pools:
Calhoun Packet Receive Pool buffers, 1560 bytes (total 256, permanent 256):
     222 in free list (0 min, 256 max allowed)
     14323 hits, 0 misses

Controller reports no significant errors other than discards:

Doctors-Temp#show controller ethernet f0/1

  Transmit                                Receive
   1333345 Bytes                          4501690 Bytes
     17091 Frames                           42219 Frames
     10227 Multicast frames                     0 FCS errors
      1019 Broadcast frames                 12253 Multicast frames
         0 Pause frames                     25775 Broadcast frames
         0 Single defer frames                  0 Control frames
         0 Multiple defer frames                0 Pause frames
         0 1 collision frames                   0 Unknown opcode frames
         0 2-15 collisions                      0 Alignment errors
         0 Late collisions                      0 Length out of range
         0 Excessive collisions                 1 Symbol error frames
         0 Total collisions                     2 False carrier errors
         0 Control frames                       0 Valid frames, too small
         0 VLAN discard frames                  0 Valid frames, too large
         0 Too old frames                       1 Invalid frames, too small
      8961 Tagged frames                        0 Invalid frames, too large
         0 Aborted Tx frames                 2871 Discarded frames

  Transmit and Receive
     11113 Minimum size frames
     41525 65 to 127 byte frames
      3359 128 to 255 byte frames
      2951 256 to 511 byte frames
       269 512 to 1023 byte frames
        91 1024 to 1518 byte frames
         1 1519 to 1522 byte frames

If you do the commands quickly in succession, the "no buffer" ,
"ignored" , and "discarded frames" are about equal.

It's running latest IOS for that platform (12.1(22)EA13) as are most of
our other 2950s.

I've also seen this on older 2924XLs (complaints of buffers / input
discards), almost always on the uplink port.

Is this just a case of the "discard tagged traffic for which I have no
destination" being reported as buffer errors, or something else entirely?

Jeff