[c-nsp] Input errors on SVIs (c2950)

[David J. Hughes]

On many, many 2950 class switches we are seeing interface input errors 
on the management SVI.  However there are no corresponding errors on 
any physical interfaces.   The traffic rates to the SVI's are very, 
very low.  Just a telnet / ssh session to the switches can generate 
these errors.  It's not an environmental issue as we are seeing these 
problems at several different locations.  Buffers look fine (no errors) 
and there's nothing being logged.  We are seeing this on boxes running 
12.1(22)EA2, EA4 and EA7.  This isn't just a cosmetic issue as we are 
seeing it impact upon our management / monitoring traffic.

Has anyone seen this or similar before?


Thanks

David
...

---
sw47.bne#sh int vlan 999
Vlan999 is up, line protocol is up
   Hardware is CPU Interface, address is 0008.a372.4e00 (bia 
0008.a372.4e00)
   Description: Network Management
   Internet address is XXX.XXX.XXX.XXX/XX
   MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
      reliability 150/255, txload 1/255, rxload 1/255
   Encapsulation ARPA, loopback not set
   ARP type: ARPA, ARP Timeout 04:00:00
   Last input 00:00:00, output never, output hang never
   Last clearing of "show interface" counters 06:25:09
   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 24000 bits/sec, 83 packets/sec
   5 minute output rate 4000 bits/sec, 7 packets/sec
      1911814 packets input, 69434847 bytes, 0 no buffer
      Received 178644 broadcasts (0 IP multicast)
      0 runts, 0 giants, 53 throttles
      872646 input errors, 0 CRC, 0 frame, 0 overrun, 89322 ignored
      159551 packets output, 30854840 bytes, 0 underruns
      0 output errors, 0 interface resets
      0 output buffer failures, 0 output buffers swapped out

sw47.bne#sh buffer
Buffer elements:
      498 in free list (500 max allowed)
      291381912 hits, 0 misses, 0 created

Public buffer pools:
Small buffers, 104 bytes (total 32, permanent 25, peak 55 @ 7w0d):
      31 in free list (20 min, 60 max allowed)
      574777070 hits, 3347 misses, 9070 trims, 9077 created
      0 failures (0 no memory)
Middle buffers, 600 bytes (total 24, permanent 15, peak 57 @ 2d12h):
      23 in free list (10 min, 30 max allowed)
      4030062 hits, 8080 misses, 24228 trims, 24237 created
      0 failures (0 no memory)
Big buffers, 1524 bytes (total 6, permanent 5, peak 27 @ 7w0d):
      6 in free list (5 min, 10 max allowed)
      797198 hits, 38485 misses, 20961 trims, 20962 created
      20797 failures (0 no memory)
VeryBig buffers, 4520 bytes (total 10, permanent 0, peak 22 @ 3w0d):
      10 in free list (0 min, 10 max allowed)
      2433075 hits, 2893 misses, 545 trims, 555 created
      2881 failures (0 no memory)
Large buffers, 5024 bytes (total 1, permanent 0, peak 6 @ 7w0d):
      1 in free list (0 min, 5 max allowed)
      2084 hits, 797 misses, 2015 trims, 2016 created
      797 failures (0 no memory)
Huge buffers, 18024 bytes (total 1, permanent 0, peak 3 @ 7w0d):
      1 in free list (0 min, 2 max allowed)
      325 hits, 472 misses, 1951 trims, 1952 created
      472 failures (0 no memory)

Interface buffer pools:
Calhoun Packet Receive Pool buffers, 1560 bytes (total 256, permanent 
256):
      223 in free list (0 min, 256 max allowed)
      492189291 hits, 0 misses