[nsp] MSFC: changing default SPD values

[lee.e.rian at census.gov]

Has anyone tried changing the input queue size and SPD values on an MSFC
and are willing to share the results?

A few years back we were having problems with input queue drops on MSFCs.
Increasing the input queue size got rid of the drops and everybody forgot
about it.  Then we upgraded to a version of IOS that had the SPD
functionality and now we've got a situation where there are no or zero
drops but 10s or 100s of thousands of input queue flushes.  Something like
this

Vlan174 is up, line protocol is up
  Hardware is Cat6k RP Virtual Ethernet, address is 0030.b636.93b0 (bia
0030.b636.93b0)
  Internet address is x.x.x.x/24
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, 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 never
  Input queue: 0/200/0/117202 (size/max/drops/flushes); Total output drops:
0
                       ^^^^^^
  Queueing strategy: fifo
  Output queue :0/40 (size/max)
  5 minute input rate 3000 bits/sec, 2 packets/sec
  5 minute output rate 5000 bits/sec, 3 packets/sec
     23147436 packets input, 2978404581 bytes, 0 no buffer
     Received 23203045 broadcasts, 0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     17913042 packets output, 3080633018 bytes, 0 underruns
     0 output errors, 0 interface resets
     0 output buffer failures, 0 output buffers swapped out

Increasing the input queue size to 200 on all interfaces does not change
the SPD values.  I'm guessing because the queue size doesn't change on the
ibc or eobc interface (sh ibc; sh eobc).  In the lab I've tried increasing
the input queue size to 200 on all interfaces and doing
ip spd queue max 199
ip spd queue min 198
and haven't noticed any problems.  I haven't had the nerve to try it on the
production network yet and was wondering if anybody knew if there were any
"gotchas" associated with something like this or if it's Just Going To
Work?

Thanks,
Lee