—-Spanning tree
Bride ID = Priority.MAC
IF LINK COST = Same
HIGHER BRIDGE ID switches port is blocked
Under show spanning-tree
root id = information about root bridge
bridge id = current device
//set spanning-tree priority
conf t
spanning-tree vlan 1 priority //OR
spanning-tree vlan 1 root primary
//portfast is used for ports that connect computers + router, stops a port from blocking.
// DO NOT USE ON A PORT THAT CONNECTED TO A SWITCH
//RAPID spanning-tree must be set EVERYWHERE
spanning-tree mode rapid
//now set the port to portfast
int fa1/0
spanning-tree portfast
—–BPDU Guard
On user access ports we enable BPDU Guard.
If a switch receives the BPDU on this port, the port will immediately shutdown preventing a loop
int Gi0/1
Spanning-tree bpdu-guard enable