[c-nsp] Gigabit Interface Input Errors

[Ryan West]

Hi,

> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> bounces at puck.nether.net] On Behalf Of Gert Doering
> Sent: Thursday, November 05, 2009 3:39 PM
.
> 
> There's not much you can do, except "get a hardware forwarding box"
> or "just accept it, and only worry if the errors increase more
> frequently".

Hopefully I'm not completing high-jacking here, but I have seen similar issues on the 4500 w/WS-X4548-GB-RJ45 line cards.  The fabric has 6gbps per slot, so the oversubscription is 8:1.  The best tell tale sign that I'm hitting oversubscription are input errors with no CRC or overruns, like below:

  30 second input rate 6394000 bits/sec, 719 packets/sec
  30 second output rate 722000 bits/sec, 481 packets/sec
     770898484 packets input, 957181248327 bytes, 0 no buffer
     Received 594832 broadcasts (560167 multicast)
     0 runts, 0 giants, 0 throttles
     282191 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 input packets with dribble condition detected
     455543646 packets output, 153140605424 bytes, 0 underruns 

Is there a more systematic approach to detecting this?  I've gone through some docs and most useful information is geared toward the 6500, such as http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a00801751d7.shtml#ASIC.  Currently I have to use a combination of interface statistics and historical Cacti graphs to narrow down over-utilized port ranges.

Thanks,

-ryan