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New Member

Growing input discards on up interfaces of N7K running 5.0.3

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
    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
    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?


Re: Growing input discards on up interfaces of N7K running 5.0.3

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.


New Member

Re: Growing input discards on up interfaces of N7K running 5.0.3

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.


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