The need for STP (Spanning tree protocol)

One of the major topics in switching is STP.

Why do we buy managed switches? Because it has capability to execute STP. Unmanaged or Dumb Switches does not implement STP. 

Why do we Need STP? Because...

To solve the problems that arises from redundant network.

3 Problems with Redundant Network

1. Broadcast Storm

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When PCa wants to communicate with PCb it will send an arp(address resolution protocol) messages. Arp messages is a broadcast messages so it will be received by all active interface connected to PCa. Flow of messages: is circling around the network thus producing a broadcast storm on the entire network except where the messages was received in our case PCa.

2. Infinite frames transmitted and received

The broadcast messages received by PCb is infinite because of the circling of broadcast messages packet inside our network. 

3.Mac Address Table Instability

When switches receives incoming frames it will update its mac address table then it will delete the previous entry received. Because the broadcast messages is circling around our network our  switches continuously changing its mac address table.