Delivery and Routing of IP Packets VI Delivery and Routing of IP Packets

Delivery Mean  the physical forwarding of packet Concepts : Connectionless and connection-oriented service Direct and indirect delivery

Connectionless vs Connection-oriented service Delivery is accomplish using either connectionless or connection-oriented service Connection-oriented: Network layer protocol first establish connection After that, a sequence of packets can be sent one after another. A packet is logically connected to the packet traveling before it and to a packet traveling after it When all packet have been delivered, the connection is terminated Route of a sequence of packet can be made only once, when the connection is established. Routers do not have to recalculated the route for each individual packet

Connectionless The network protocol treats each packet independently, with each packet having no relationship to any other packet. Packets may not travel the same path to their destination IP protocol is a connectionless protocol. It is designed this way because IP, as an internetwork protocol, may have to deliver the packets through several heterogeneous network If IP were to be connection-oriented, all of networks in the internet should also be connection-oriented, which is not the case

Direct versus Indirect Delivery

Figure 6-1

Figure 6-2

Routing Methods Next- Hop routing Network-specific routing Host-specific routing Default routing

Figure 4-3

Network specific routing Figure 6-4 Network specific routing

Figure 6-5 Host specific routing

Figure 6-6 Default routing

Static vs Dynamic Routing Static routing table contains information entered manually ADM enters the route for each destination in table When a table is created, it cannot update automatically when there is a change in the internet Can be used in a small internet or in an experimental internet for troubleshooting Dynamics routing table is updated periodically using one of the dynamic routing protocol such a RIP, OSPF, or BGP Whenever there is a change in the internet, such as shut down of a routers or breaking of a link, the dynamic routing protocols update all of the tables in the routers (and eventually in the host)

Figure 6-7

Figure 6-8

Figure 6-9