Growing input discards on up interfaces of N7K running 5.0.3

[alex.de.gracia]

Hi Guys,

My set up is 2 x 7010s port channeled to 2 x 6500s and plain trunks to 2 x 3560s.

I am receiving a large amount of growing input discards on all interfaces connected to either a 6500 or 3560. One is a port channel trunk and another is just a plain 1q trunk.

The link between the pair of 7010s are showing no errors.

I tried to do a bit of troubleshooting to determine what kind of discards they are but i am still unclear.

ang13csw02# sh mod

Mod  Ports  Module-Type                      Model              Status

---  -----  -------------------------------- ------------------ ------------

1    48     1000 Mbps Optical Ethernet Modul N7K-M148GS-11      ok

5    0      Supervisor module-1X             N7K-SUP1           active *

10   32     10 Gbps Ethernet Module          N7K-M132XP-12      ok

Mod  Sw              Hw

---  --------------  ------

1    5.0(3)          1.2

5    5.0(3)          1.6

10   5.0(3)          1.8

ang13csw02# sh int po100

port-channel100 is up

  Hardware: Port-Channel, address: c84c.7563.dc11 (bia c84c.7563.dc11)

  Description: 4Gbps to xxxxxxxxx

  MTU 1500 bytes, BW 4000000 Kbit, DLY 10 usec,

     reliability 255/255, txload 1/255, rxload 1/255

  Encapsulation ARPA

  Port mode is trunk

  full-duplex, 1000 Mb/s

  Input flow-control is off, output flow-control is off

  Switchport monitor is off

  EtherType is 0x8100

  Members in this channel: Eth1/6, Eth1/7, Eth1/8, Eth1/9

  Last clearing of "show interface" counters never

  30 seconds input rate 6009344 bits/sec, 1268 packets/sec

  30 seconds output rate 2094360 bits/sec, 618 packets/sec

  Load-Interval #2: 5 minute (300 seconds)

    input rate 10.26 Mbps, 1.68 Kpps; output rate 5.33 Mbps, 1.03 Kpps

  RX

    37996608 unicast packets  25382130 multicast packets  6874827 broadcast packets

    70253565 input packets  25691888504 bytes

    0 jumbo packets  0 storm suppression packets

    0 runts  0 giants  0 CRC  0 no buffer

    0 input error  0 short frame  0 overrun   0 underrun  0 ignored

    0 watchdog  0 bad etype drop  0 bad proto drop  0 if down drop

    0 input with dribble  10544890 input discard

    0 Rx pause

  TX

    24844804 unicast packets  335386 multicast packets  67535 broadcast packets

    25247725 output packets  11191403438 bytes

    0 jumbo packets

    0 output error  0 collision  0 deferred  0 late collision

    0 lost carrier  0 no carrier  0 babble

    0 Tx pause

  4 interface resets

Is there anything else i should look for?

[Andrew Gossett]

Hi Alex,

Frames from unallowed vlans on N7k trunk interfaces will increment input discards.  I recommend first verifying the vlans that exists and are allowed on the nexus and the downstream switch match.

-Andy

[alex.de.gracia]

I do have some sort ot vlan load balancing going on and i will start pruning and turni

ng off VTP as i go through each access switch.

Is the input discards more or less cosmetic and hold no detriment to the network?

I ask because my N7K is running about 7% CPU and processing an average of 5mbps which is nothing for this switch.

Thanks