Friday, April 17, 2020

Cisco nexus CRC error on interface

Folks,

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Image - https://imgur.com/a/lFq5nmq

I have dual stack vPC setup between 4 cisco nexus switch as per above design. I have noticed recently that getting CRC error on cisco 3064 all 4 interface connected to N9K, and during peak traffic time getting more CRC error, these error are not very high also per minute i would say 1 or 2 error randomly popping up on those 4 interfaces. I know CRC has direct connection with Layer 1 (cable, port etc..) but in my case how can be possible both switches and all 4 interface throwing CRC?

After clear counter

# show interface e1/51-52 counters errors -------------------------------------------------------------------------------- Port Align-Err FCS-Err Xmit-Err Rcv-Err UnderSize OutDiscards -------------------------------------------------------------------------------- Eth1/51 0 12 0 12 0 0 Eth1/52 0 20 0 20 0 0 -------------------------------------------------------------------------------- Port Single-Col Multi-Col Late-Col Exces-Col Carri-Sen Runts -------------------------------------------------------------------------------- Eth1/51 0 0 0 0 0 0 Eth1/52 0 0 0 0 0 0 -------------------------------------------------------------------------------- Port Giants SQETest-Err Deferred-Tx IntMacTx-Er IntMacRx-Er Symbol-Err -------------------------------------------------------------------------------- Eth1/51 0 -- 0 0 0 0 Eth1/52 0 -- 0 0 0 0 

Interface config

interface Ethernet1/51 description *** vPC trunk to N9K *** switchport mode trunk switchport trunk allowed vlan 10-12,20-22,27-32,39-40,50,100,200,300 speed 40000 channel-group 3 mode active interface Ethernet1/52 description *** vPC trunk to N9K *** switchport mode trunk switchport trunk allowed vlan 10-12,20-22,27-32,39-40,50,100,200,300 speed 40000 channel-group 3 mode active 

what else could be wrong here, my peak traffic usage on these switches around 10 to 20Gbps during peak.

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If you see image screenshot, you will noticed signwave between e1/51 and e1/52 so in day e1/51 has more CRC error and in night e1/52 has more errors, that doesn't make sense to me



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