The Role of BPDU Guard in Spanning Tree As a ccnp / ccsp candidate you are anticipated to grasp the purpose and function of Spanning-tree BPDU guard. The CCNA / CCNP's exam will ask of you to determine the purpose of the BPDUGuard (Bridge Protocol Data Unit) throughout the spanning-tree protocol. Before we go into detail as to the purpose of the BPDU Guard function a fast recap on the spanning-tree protocol is required. Spanning-tree is a protocol which is designed to prevent physical and/or logical loops in your layer 2 network. Spanning-tree achieves this loop free atmosphere by first of all electing a device to act as the point of interest of the community which all different switches measure themselves from. This point of interest function is an elected role. The election of the focus often called the "Root Bridge" is done at the very start of spanning-tree determining the loop free topology, the election of the Root Bridge is carried out through the use of a combination of the switches MAC deal with and a value often known as the "Default Priority". These two values are conveyed into the community through BPDU's. BPDU's are utilized by spanning-tree to keep up a stable state network. In standard 802.1D spanning-tree for example solely the Root Bridge generated a BPDU. The soundness of the Root Bridge is of paramount significance within the operation and continuous uninterrupted service of spanning-tree. A change in the place of the Root Bridge will cause service disruption on the network with data and voice session timing out. In ccvp it is very important consider what occasions could trigger a change in the place of the Root Bridge, events reminiscent of hyperlinks failing between the present Root Bridge and the rest of the community would cause a change, or possibly a duplex mismatch between the Root Bridge and downstream switches inflicting the spanning-tree messages from the Root Bridge from reaching the opposite parts of the network. These events are easily fixed and resolved none of which might require using the BPDU Guard feature. As described in ccna wireless it is very important that in our community we need to enforce the Spanning-tree domain borders and hold our active topology and the position of our Root Bridge predictable.