Networking and Internetworking Devices. Repeaters Bridges Routers Gateways Routing Algorithms. Outline. Routing Algorithms Dykstra Bellman Ford Routing In the Internet DNS. Router and the OSI Model. Routers in an Internet. Distance Vector Routing. Knowledge about the entire network
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Networking and Internetworking Devices • Repeaters • Bridges • Routers • Gateways • Routing Algorithms
Outline • Routing Algorithms • Dykstra • Bellman Ford • Routing In the Internet • DNS
Distance Vector Routing • Knowledge about the entire network • Routing only to neighbors • Information Sharing with neighbors
Link State Routing • Knowledge of neighborhood • Shares with all routers – flooding • Information sharing when change
Dijkstra Algorithm • Find the shortest paths from a given source node to all other nodes by developing paths of increasing path length • Do this until paths to all nodes are found • From ROOT • Do until destination is reached. • Take shortest arc to next node • Add this arc to path • ROOT = this->node • Breadth Search from root • Select lowest cost • Add node and arc
Bellman-Ford • Do until a path exists to each node • Develop paths in increasing depth • While n < maxLength or until allNodesFound • Find all paths of length n • n++
Distance Vector Routing Protocol • RIP (Routing Information Protocol) • Each router uses broadcasting to send its entire information to its neighbors every 30 seconds. • The best path is based on the least number of hops. • It’s suitable for small networks • RIP is used by IPX/SPX and TCP/IP.
Routing Algorithms • Link state routing • If there is a change, each router sends its information about its neighbors to every other router in the network using flooding. • A router, periodically sends a message to its neighbors, the response indicates that the device is alive and functioning. • No response, change has occurred.
Link State Routing Protocol • OSPF (Open Shortest Path First) • More efficient than RIP • Only the changes are sent • each router sends its information about its neighbors to every other router in the network using flooding. • A router, periodically sends a message to its neighbors, the response indicates that the device is alive and functioning. • No response, change has occurred.
Routing in the Internet • Physical Address Determination • Must know physical address to route • arp • Selection of inter-network gateways • tracert • Symbolic and Numeric Addresses • nslookup
Physical Address Determination • ARP • The arp program displays and modifies ip to mac address translation • a -> display all entries in table • d -> delete a host entry Login to sheba type “arp sheba” type “arp –a”
tracert • Login to sheba • Type “tracert www.memphis.com” • This shows the route that a packet takes to communicate with U of Memphis webserver
DNS - nslookup • nslookup www.cbu.edu • What is displayed? • CNAME
What ports • Type “more /etc/services” • This displays the services on sheba and the ports they operate on.