Bridges, LANs and the Cisco IOS
Shivendra S. Panwar, Shiwen Mao, Jeong‐dong Ryoo, Yihan Li · Cambridge University Press eBooks · 2004
Algorhyme I think that I shall never see A graph more lovely than a tree. A tree whose crucial property Is loop-free connectivity. A tree that must be sure to span So packets can reach every LAN. First, the root must be selected. By ID, it is elected. Least-cost paths from root are traced. In the tree, these paths are placed. A mesh is made by folks like me, Then bridges find a spanning tree. Radia Perlman Objectives The Cisco Internet Operating System software. Configuring a Cisco router. Transparent bridge configuration and operation. The spanning tree algorithm. Ethernet bridges Use of bridges Bridges are link layer devices. As illustrated in Fig. 0.3, when two network segments with different link and physical layer protocols are connected, the bridge performs a two-way translation of the protocols. The data section of a transit frame is extracted and re-encapsulated in the frame format used by the next-hop network segment. However, there are several reasons to use bridges to connect networks even with identical protocols, rather than using a large network without bridges. First, network segments could be far away from each other but still work within the same logical network. In this case, two remote network segments can be linked by two bridges via a point-to-point wide area link. Second, there is a limit on the maximum length of the shared medium in a local network.