Description: Identifier of the designated root bridge. This is an 8 byte hexadecimal label composed of the bridge priority level (the first 2 bytes) and the address of the adapter connecting the bridge to the LAN segment with the lowest LAN segment number. The root bridge has the lowest bridge identifier of all bridges in the network, and is at the top of the spanning tree. It is also the bridge that sends the 'HELLO' message to detect when other bridges enter and leave the network. The root bridge usually carries the greatest amount of traffic, since it connects the two halves of the network together.