In our network we have about 90 switches. All core and distribution layer switches have redundant links. Spanning tree is configured and seems to be working, in that is is blocking appropriate ports. Cisco Network assistant is an easy way to see this.
However when I sniff traffic on an ordinary port on any switch I can see traffic that should not be there. The port is not spanned or anything. But I can see some traffic between hosts that is not broadcast traffic and none of which should be on that port.
The thing is that the more loops that I put in the network the worse it gets, even though STP takes care of it. As a result it seems that during high traffic usage there can be times that uplinks to dist switches are overloaded and discard packets due to no buffers.
Most switches have uplink ports set to priority 16 or 32 to determine which is primary etc. But not all, is this a problem?
There is a root set. There a many VLANs on the network.
I can only think that there is a spanning tree problem with my config.
Where do I start looking?