Distributed Spanning Tree Algorithm essays

Distributed Spanning Tree Algorithm essays The Distributed Spanning Tree Algorithm (DSTA from now on...) is used to make sure that you dont get a loop when you set up your network in a loop form, if that makes any sense. Okay, when you set up a network you want it to be reliable, and setting it up in a loop form allows it to have multiple routes to get to each separate computer (node of the tree). But you cant allow it to use all of the nodes at once because if it completes the loop (the information gets back to the computer that sent it) there can be an error. What the DSTA does is find out the shortest path that will reach to every computer and mark that as the root path. That path will remain open and then the DSTA finds the shortest paths from the root path to all the other computers and it closes down all the other unneeded ports so that it doesnt complete a loop. All right, this is how it works: first off, each bridge sends a message out of each of its ports. This message sets the bridge's id as root-bridge and as a transmitter and has 0 as its cost. This message is saved at each port as the configuration for that port and as the configuration for the bridge. When a message is received at a port, if its better than the current configuration of the port, it becomes the new configuration of this port. If that port becomes the port with the best configuration out of all the ports on that particular bridge, it is said to be the root-port of the bridge and is set to be an active port. The configuration of the root-port is changed to a transmitting port, and the cost is incremented by one. If this is better than the overall configuration of the bridge, it becomes the new configuration of the bridge. After this comparison, the new configuration is compared to the configurations of all the non-root ports. If the configuration of one of these n on-root ports is worse than the configuration of that bridge, the port it is changed to active. It do...