STP is usage on switches to avoid loops on SIP network. The implementation of this process is through spanning tree algorithm to disable the unwanted blocks or links in port which causes loops. Duplicate frames and Loops can root severe effects on the network. Most LANs are designed to cater redundancy; if a link fails the other one can overtake it, by forwarding the frames transversely through LAN.

The switches on the port can detect MAC address of PC or host. By sending the message to another switch in the network is to notify its knowledge in getting into PC. The problem arises when the other host or PC discovers that switches are similar to other PC’s MAC address. Mean while all the messages will start flooding in the network and the switches will not know how to discover PC or host and thus formation of Loop.

Spanning Tree Protocol ensures one logical path for all destinations in network by blocking of redundant path which can cause Loop. When the loops are detected by the switches it immediately blocks the one or more path in forming of loops.

To stop the formation of Loop, one switch is chosen by network that is Root Bridge and  Root port are selected by other switches , later which  Designated port  are selected by segments by closing down all the ports.

Cisco has default STP switches therefore no configurations required. STP regularly monitors the failure in network, any topology network changes or switch port.


Spanning Tree Protocol (STP)