[c-nsp] quick spanning tree question

[Stig Johansen]

Cord MacLeod wrote:
>Does this give enough information?  From my understanding of spanning tree, g0/46 should not be used for any traffic.  >g0/45 is the root port for all vlans.

Spanning tree doesn't determine where traffic flows, it determines which ports are active or blocking in their respective VLANs (according to the STP-protocol and design) to avoid loops. It's the switch CAM / mac-address-table which determines where a single packet will be forwarded. If the MAC-address is unknown/not recorded in the table, the switch will forward/broadcast the packet to all active ports in the VLAN. 

In your situation, both g0/45 and g0/46 are active ports in many VLANs (not blocking), so the traffic you are seeing is traffic which the switch doesn't know where to forward and subsequently broadcasted to all active ports in the respective VLANs.

You need to do some sniffing on the traffic out the g0/46-port to learn where it comes from and to where it's supposed to go. After learning this and understanding the whole picture, you can make the necessary adjustments in the network/servers.

Best regards,
Stig Meireles Johansen