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New Member

Interface errors on 6509

Since upgrading our core 6509 to a brand new 6509 sup720 we have noticed some strange Receive Errors on a number of interfaces. These interfaces all share common characteristics - they are all access ports, connecting to identical switches.

The errors are shown below

SRPCC#sh interfaces gigabitEthernet 1/2 counters errors

Port Gi1/2 Rcv-Err 7874

SRPCC#sh interfaces gigabitEthernet 1/2 counters trunk

Port Gi1/2 WrongEncap 7874

This would indicate an error with the trunking configuration but this is the config of the interfaces.

Core switch (this is interface with errors)

interface GigabitEthernet1/2

no ip address


switchport access vlan 103

switchport mode access

switchport nonegotiate

spanning-tree cost 3


Access switch

interface GigabitEthernet0/1

switchport mode access

switchport nonegotiate

spanning-tree portfast disable

spanning-tree vlan 1 cost 4


I know we are bridging the VLAN's but this has been the design for some time. Prior to the 6509 upgrade we were not seeing these errors.

The errors also occur one every 30 seconds which would lead me to think it is DTP, but switchport nonegotiate should disable DTP completely.

Any ideas?


New Member

Re: Interface errors on 6509


Could it be somehow connected to new modules/software ability to customize EtherType?

I mean that old software simply didn't check this field in packets header but the new one checks and generates the error.

//Mikhail Galiulin

New Member

Re: Interface errors on 6509

I was already thinking along these lines as the old 6509's were running hybrid with sup1a's and MSFC 1 cards. CatOs was version 6.3

As part of the upgrade we migrated to running native.

If this is the case - ie it's new functionality in the code picking up the error, is there anything that can be done to stop the errors being reported? Or more to the point what could be causing the WrongEncap error?


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