3Com 3C840 manual Network, Organization, Structure, Physical Layout

A-6APPENDIX A: BRIDGING AND ROUTING

	other bridges detect this and reconfigure their ports so that there is once
	again an active data path through the network.
Network Topology	If your network topology is star shaped, a combination of analog
	modems and bridging is usually the most efficient and successful option.
	Routing is a better solution if your network is a complex mix of WAN
	interconnects and/or multiple protocols.
Broadcast Storms	Bridges are programmed to forward data packets automatically by
	default while routers filter data packets by default. These attributes have
	an impact on the overall flow of data across the network. Much has been
	made of broadcast storms in connection with bridged networks, where
	the broadcast signals from bridges propagate to fill all of the wide area
	bandwidth, and bring the network down. Broadcast storms cannot be
	attributed to installation of bridges or routers, but by poor protocol
	implementation and network design. However the deployment of routers
	can effectively firewall one logical network from another.
Optimum Use of	Bridged networks use Spanning Tree Protocol (STP) to provide network
Resource	resilience, by retaining redundant links on standby, in case the primary
	link fails. This means that you are not making maximum use of available
	resources.
	Routing protocols make each node aware of the primary and alternate
	routes available, ensuring that resources (particularly WAN links) are not
	wasted.
	Routers have been designed to provide the optimum route through the
	network from the workstation through to the destination resource with
	which the user wishes to communicate. In a very large network there
	could be multiple paths available, and these could change as links go in
	or out of service. These changes in network topology are handled by
	routing protocols.
Network	Some organizations are structured into departments determined by the
Organization,	physical layout of their work environment, so it is natural to divide the
Structure, and	corporate network into separate logical networks. Routing becomes the
Physical Layout	obvious candidate for handling these individual LANs.