The Distributed Spanning Tree Algorithm (DSTA from now on…) is used to make sure that you don’t 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 can’t 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 al
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This message sets the bridge's id as root-bridge and as a transmitter and has 0 as its cost. It does this to check to see if using this port will create a better circuit within the network than the one that is currently in use. When a message is received at a port, if it’s better than the current configuration of the port, it becomes the new configuration of this port. When a port goes from the inactive to the active state, the transition will be delayed a bit to make sure that any other ports that were supposed to go from active to inactive have actually been able to finish doing that.
All right, this is how it works: first off, each bridge sends a message out of each of its ports. If it doesn’t do this, there is a chance that a loop may be formed, which is something that is very unwanted. If the configuration of one of these non-root ports is worse than the configuration of that bridge, the port it is changed to active. 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. In all, the Spanning Tree is made up of all the bridges and their active ports that have been marked as active and the segments of wire that are connecting them together. This message is saved at each port as the configuration for that port and as the configuration for the bridge. After this comparison, the new configuration is compared to the configurations of all the non-root ports. If this is better than the overall configuration of the bridge, it becomes the new configuration of the bridge. l the other computers and it closes down all the other unneeded ports so that it doesn’t complete a loop. The configuration of the root-port is changed to a transmitting port, and the cost is incremented by one.
Approximate Word count =
492
Approximate Pages =
2 (250 words per page double spaced)
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