Networking and internetworking devices

Repeater

Hub

Function of a bridge Regenerate and filter traffic Check destination address Forwards the new copy to the segment to which the address belongs

Multiport bridge

Connecting LAN segments in two buildings

Router

Gateway

Gateway is a protocol converter IBM Novell

Switch

Backbone

Routing algorithms Calculate the shortest path between two routers –Distance vector routing –Link state routing

In distance vector routing, each router periodically shares its knowledge about the entire network with its neighbors Network ID Cost Next Hop (ID of the next router) The cost is base on hop count 1= No hop Routing table hop 14 2 B 55 2 B B B B 78 1 A’s new table

Final routing table

In link state routing, each router shares its knowledge of its neighborhood with all routers in the internetwork Flooding router sends its info. to all of its neighbors, each neighbor sends the packet to all of its neighbors, and so on. Link state packet (LSP) Advertiser ID Destination network ID Cost Neighbor ID Initialization Each router sends a short greeting packet to its neighbor Prepare an LSP, Floods the network Every router receivers every LSP, Puts the info. Into a Link state database Flooding of A’s LSP

Every router has the same Link state database

Dijkstra’s Algorithm finds shortest paths from given source node s to all other nodes by developing paths in order of increasing path length algorithm runs in stages. each time adding node with next shortest path algorithm terminates when all nodes processed by algorithm

Link state routing table for router A โดยใช้ Dijkstra Algorithm

Link state routing table for router A

Bellman-Ford Algorithm find shortest paths from given node subject to constraint that paths contain at most one link find the shortest paths with a constraint of paths of at most two links and so on

Example of Bellman-Ford Algorithm