[c-nsp] Huge number of input queue drops on 6500

[Pshem Kowalczyk]

Hi All,

We just discovered a very weird problem, we're not sure what to
attribute it to. We run a port-channel between a cisco (6509E,
WS-X6548-GE-TX) and a Huawei NE40E. Port channel consists of 2 copper
links and runs at about 1.2G. We've noticed huge number of input queue
drops and overruns:

akl-grafton-bdr1#sh int gi2/8 controller
GigabitEthernet2/8 is up, line protocol is up (connected)
  Hardware is C6k 1000Mb 802.3, address is 0009.1259.50ab (bia 0009.1259.50ab)
  Description: akl-grafton-edge2 (gi1/0/1)
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 2/255, rxload 134/255
  Encapsulation ARPA, loopback not set
  Full-duplex, 1000Mb/s
  input flow-control is off, output flow-control is desired
  Clock mode is auto
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input never, output 00:00:16, output hang never
  Last clearing of "show interface" counters 00:08:10
  Input queue: 0/2000/2456215/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  5 minute input rate 527858000 bits/sec, 84768 packets/sec
  5 minute output rate 8797000 bits/sec, 4316 packets/sec
     37730092 packets input, 29406534349 bytes, 0 no buffer
     Received 2546 broadcasts (864 multicast)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 2456196 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     1923154 packets output, 495893834 bytes, 0 underruns
     0 output errors, 0 collisions, 0 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

the port-channel status:
                Channel-group listing:
                -----------------------

Group: 1
----------
                Port-channels in the group:
                ----------------------

Port-channel: Po1
------------

Age of the Port-channel   = 227d:06h:23m:31s
Logical slot/port   = 14/1          Number of ports = 2
GC                  = 0x00000000      HotStandBy port = null
Port state          = Port-channel Ag-Inuse
Protocol            =    -

Ports in the Port-channel:

Index   Load   Port     EC state        No of bits
------+------+------+------------------+-----------
  1     55     Gi2/5    On/FEC    4
  0     AA     Gi2/8    On/FEC    4

Time since last port bundled:    31d:19h:44m:47s    Gi2/5
Time since last port Un-bundled: 123d:16h:48m:20s    Gi2/8


the overruns and input queue drops show on both interfaces. I suspect
it might have something to do with the port-channel, since none of the
native links between our Cisco and Huawei seems to suffer from the
same problem. I cannot easily  replace the port channel, and after
reading some documentation the only thing I found that could
potentially help is to change the hold-queue on the 6500.

The other end doesn't show any issues and packets are only getting
dropped from the NE40E to the 6500.
I know that the issue might not be caused by cisco, but perhaps any of
you encountered something similar

kind regards
Pshem