I had a strange thing happen yesterday, I have 3 switches, A,B,C both B and C connect to A on a single connection, the connection from B to A is on a single vlan and just a normal access port, the connection from C to A was a trunk port with many vlans.
For some reason when we added switch C, the access port on switch A went into blocking mode, saying
8w0d: %SPANTREE-7-RECV_1Q_NON_TRUNK: Received 802.1Q BPDU on non trunk GigabitEthernet0/23 VLAN196.
8w0d: %SPANTREE-7-BLOCK_PORT_TYPE: Blocking GigabitEthernet0/23 on VLAN0196. Inconsistent port type.
Is it right that the bpdu's from switch C's trunk will go out of the access port on the other switch and block the link? I have never seen this.
The only way to fix it was to turn off spanning tree on switch C, or I guess the other way would be to set the port between A and B a trunk port?
question is why did this happen?