NX 7000 : bpduguard errdisable

[Rosa Ladeira]

bpduguard errdisable : is it a consequence of a fisical connection loop ?

[Amit Singh]

This shows up when you have BPDU guard configured on the switch typically on host ports/ port fast ports and you connect a switch to those ports. As those ports do not expect a BPDU, when received they put the port into error disable state. This is to prevent the physical loop in the topology if someone connects a wrong cable.

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[Rosa Ladeira]

Well this error raises when I attached a DELL switch to a NX2000 port.

There is a errdisable recovery cause bpduguard command on NX7000 configuration.

Is there any special configuration for this connection ?

[Rosa Ladeira]

in addition

spanning-tree port type network

command fails on nx2000 port

[manju.cisco]

Hi,

I haven't worked on Nexus, but based on switching, i can say you that when a access port enabled with bpduguard would go to error-disabled state if the port receives a BPDU gaurd,  If error disable recovery mechanism is configured the port would try to recover itself for certain amount of time, and comes up, if it again received BPDU on the port it will be put into error-disabled state again and this continues.

To avoid this, configure that port as trunk port if you want a switch to be connecting on that port.

Or you can enable bpdu filter to discard the BPDU's.

[Amit Singh]

yes this is the expected behaviour when you connect any switch to nexus 2000 FEX. The FEX ports are optimised to connect the host ports only not the switch.you have BPDU guard and loop guard enable on FEX ports by default hence the expected behaviour. You should not connect any switch on the FEX ports, it's not recommended and might introduce some loops within your network. You can uplink switches to the FEX by filtering the BPDU's on the uplink ports to the FEX or configure them as Flex links which might not be supported on Dell switches. As I mentioned, it is not recommended to connect switches to the FEX so please avoid that.

HTH, please rate if ti does.

-amit Singh

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[Amit Singh]

Please check the following documentation on host ports.

http://www.cisco.com/en/US/docs/switches/datacenter/nexus2000/sw/configuration/guide/Cisco_Nexus_2000_Series_Fabric_Extender_Software_Configuration_Guide_Release_4_2_chapter2.html#con_1046083

Cheers,-amit singh

[Rosa Ladeira]

as you have said :

"...

yes this is the expected behaviour when you connect any switch to nexus  2000 FEX. The FEX ports are optimised to connect the host ports only not  the switch.you have BPDU guard and loop guard enable on FEX ports by  default hence the expected behaviour. You should not connect any switch  on the FEX ports, it's not recommended and might introduce some loops  within your network. You can uplink switches to the FEX by filtering the  BPDU's on the uplink ports to the FEX or configure them as Flex links  which might not be supported on Dell switches. As I mentioned, it is not  recommended to connect switches to the FEX so please avoid that. "

Is it also true when connecting a NX5000 instead a NX2000 ?

Thanks,

Rosa