N3k and 3750X dot1q

[madsdahlgren]

I am having some problems with my new setup.

Coreswitch is a N3K, access switch is a 3750X.

I use auto provisioning for the 3750X.

To be able to do this, the 3750X needs to be clean when it starts up.

Then it should get an address in VLAN1, get the right DHCP option and then download the right config.

To be able to make that work, I need to set the port as trunk on my N3K, but as access on the 3750X (because it has to be clean, to be able to get the config file).

When the link comes up, it disables with the following error message:

*Jan 2 00:02:18.672: %SPANTREE-7-RECV_1Q_NON_TRUNK: Received 802.1Q BPDU on non trunk TenGigabitEthernet1/1/2 VLAN1.
*Jan 2 00:02:18.672: %SPANTREE-7-BLOCK_PORT_TYPE: Blocking TenGigabitEthernet1/1/2 on VLAN0001. Inconsistent port type.

Is there any way to get around this?

I get that normally you dont want trunk port in one end, and access port in the other, but as soon as the 3750X has been configured, it will change the uplink port to trunk.

This method does work with 3750X as core switch and 2960 as access switch, so I know it can be done :-)

[Mark Malone]

hi
you could turn off stp on that port by using stp bpdufilter but its a dangerous option as never recommended to turn off stp
safe option is console in and do it from cli , dont use auto provisioning

[lucasfreitas83]

Hello madsdahlgren,

I think that you need configure BPD filter in this port.

So it's like there is no STP on the port.

S2(config)#interface eth0/0

S2(config-if)#spanning-tree bpdufilter enable

Please rate and mark posts accordingly if you have found any of the information provided useful.
It will hopefully assist others with similar issues in the future.

Best regards,
Lucas Freitas