[c-nsp] Troubleshooting Input Queue Drops on 7600 running 12.2(33)SRC5

[Devon True]

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On 6/30/2010 11:30 AM, Devon True wrote:
> All:
> 
> I am seeing increasing input queue drops on a 7600 running 12.2(33)SRC5
> on a SPA-2X1GE in a 7600-SIP-400.
> 
> #sh int g1/1/1
> GigabitEthernet1/1/1 is up, line protocol is up
>   Hardware is GigEther SPA, address is 001d.7170.3500 (bia 001d.7170.3500)
>   Description:
>   Internet address is x.x.x.x/yy
>   MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
>      reliability 255/255, txload 72/255, rxload 46/255
>   Encapsulation ARPA, loopback not set
>   Keepalive not supported
>   Full Duplex, 1000Mbps, link type is force-up, media type is SX
>   output flow-control is unsupported, input flow-control is unsupported
>   ARP type: ARPA, ARP Timeout 04:00:00
>   Last input 00:00:00, output 00:00:00, output hang never
>   Last clearing of "show interface" counters 01:44:10
>   Input queue: 0/75/1707/0 (size/max/drops/flushes); Total output drops: 0
>   Queueing strategy: fifo
>   Output queue: 0/40 (size/max)
>   5 minute input rate 183245000 bits/sec, 41346 packets/sec
>   5 minute output rate 283924000 bits/sec, 55078 packets/sec
>      256319513 packets input, 149816057859 bytes, 0 no buffer
>      Received 5 broadcasts (0 IP multicasts)
>      0 runts, 1707 giants, 0 throttles
>      1707 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
>      0 watchdog, 0 multicast, 0 pause input
>      308870586 packets output, 193458081331 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
> 
> I also ran "sh int g1/1/1 switching" and it looks like the RP is
> dropping the packets.
> 
> #sh int g1/1/1 switching
> GigabitEthernet1/1/1
>           Throttle count          0
>         Drops         RP       1706         SP          0
>   SPD Flushes       Fast          0        SSE          0
>   SPD Aggress       Fast          0
>  SPD Priority     Inputs       7257      Drops          0
> 
>      Protocol       Path    Pkts In   Chars In   Pkts Out  Chars Out
>         Other    Process          0          0          0          0
>             Cache misses          0
>                     Fast          0          0          0          0
>                Auton/SSE      15978     958680          0          0
>            IP    Process   80379934 7498092736   42273104 3084247027
>             Cache misses          0
>                     Fast   68341283 5017154676    1197481   86714780
>                Auton/SSE 401843915443 245108148367129 516300637842
> 386876899705145
>       DEC MOP    Process          0          0      31700    2440900
>             Cache misses          0
>                     Fast          0          0          0          0
>                Auton/SSE          0          0          0          0
>           ARP    Process      15978     958680      15866     951960
>             Cache misses          0
>                     Fast          0          0          0          0
>                Auton/SSE          0          0          0          0
> 
> Any advice on troubleshooting? I looked at
> http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a0080094791.shtml
> and "show buffers input-interface g1/1/1 header" does not display any
> data and performing "debug ip packet" on a production router may not be
> in my best interests. :)

The issue was that the MTU on the other side of the link was ~9000 but
our MTU is 1500. Once both sides were equal, the errors stopped.

Thanks to all who responded with advice.

- --
Devon
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