This chapter describes the delivery and forwarding of IP packets. Delivery refers to the way a packet is handled by the underlying networks under the control of the network layer. Concepts such as direct and indirect delivery are discussed. Forwarding refers to the way a packet is delivered to the next station. We discuss two trends in forwarding: forwarding based on destination address of the packet and forwarding based on the label attached to the packet. | Chapter 6 Delivery and Routing of IP Packets CONTENTS CONNECTION DELIVERY ROUTING METHODS STATIC AND DYNAMIC ROUTING ROUTING TABLE AND MODULE CLASSLESS ADDRESSING CONNECTION-ORIENTED VERSUS CONNECTIONLESS SERVICES In a connection-oriented situation, the network layer protocol first makes a connection. In a connectionless situation, the network layer protocol treats each packet independently, with each packet having no relationship to any other packet. DIRECT VERSUS INDIRECT DELIVERY Figure 6-1 Direct delivery Figure 6-2 Indirect delivery ROUTING METHODS Figure 6-3 Next-hop routing Figure 6-4 Network-specific routing Figure 6-5 Host-specific routing Figure 6-6 Default routing STATIC VERSUS DYNAMIC ROUTING A static routing table contains information entered manually. A dynamic routing table is updated periodically using one of the dynamic routing protocols such as RIP, OSPF, or BGP. ROUTING TABLE AND ROUTING MODULE Figure 6-7 Routing module and routing table Figure | Chapter 6 Delivery and Routing of IP Packets CONTENTS CONNECTION DELIVERY ROUTING METHODS STATIC AND DYNAMIC ROUTING ROUTING TABLE AND MODULE CLASSLESS ADDRESSING CONNECTION-ORIENTED VERSUS CONNECTIONLESS SERVICES In a connection-oriented situation, the network layer protocol first makes a connection. In a connectionless situation, the network layer protocol treats each packet independently, with each packet having no relationship to any other packet. DIRECT VERSUS INDIRECT DELIVERY Figure 6-1 Direct delivery Figure 6-2 Indirect delivery ROUTING METHODS Figure 6-3 Next-hop routing Figure 6-4 Network-specific routing Figure 6-5 Host-specific routing Figure 6-6 Default routing STATIC VERSUS DYNAMIC ROUTING A static routing table contains information entered manually. A dynamic routing table is updated periodically using one of the dynamic routing protocols such as RIP, OSPF, or BGP. ROUTING TABLE AND ROUTING MODULE Figure 6-7 Routing module and routing table Figure 6-8 Routing Table Flags U The router is up and running. G The destination is in another network. H Host-specific address. D Added by redirection. M Modified by redirection. Figure 6-9 Configuration for routing example Mask Dest. Next Hop I. -- m0 - m2 - m1 ------------------------------------------------------------------------------------- m0 ------------------------------------------------------------------------------------- m0 m0 ------------------------------------------------------------------------------------- m0 Example 1 Router R1 receives 500 packets for destination ; the algorithm applies the masks row by row to the destination address until a match (with the value in the second column) is found: Solution Direct delivery & .
