Spanning Tree Protocol: Electing a Root Switch

In Spanning Tree, on any given VLAN there can only be one Root.  In order to determine which switch becomes the root, Spanning Tree holds an election to determine which switch becomes the root.

  1. Each switch begins by creating and sending an STP Hello BPDU message, claiming that itself is the root switch.
  2. If a switch hears a superior Hello better than it’s own Hello that contains a lower RBID, it stops claiming that its the root on its own BPDUs and starts forwarding the better BPDU to all other switches.
  3. Eventually all switches receive the superior BPDU and that switch wins the election.

rootelection

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s