Network layer Part 3
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This document discusses network layer concepts related to delivery and forwarding of IP packets. It describes two types of forwarding - destination address-based forwarding for connectionless protocols like IP, and label-based forwarding for connection-oriented protocols using IP. Destination address-based forwarding techniques include next-hop, network-specific, host-specific, and default methods. The document also discusses forwarding with classful addressing, subnetting, and classless addressing, and introduces the concept of address aggregation to reduce routing table sizes.
Network layer Part 3
- 1. 4 Tutun Juhana Telecommunication Engineering Network Layer (Part 3) School of Electrical Engineering & Informatics Institut Teknologi Bandung Computer Networks
- 2. DELIVERY AND FORWARDING OF IP PACKETS
- 5. Forwarding • Forwarding means to place the packet in its route to its destination – to deliver the packet to the next hop (which can be the final destination or the intermediate connecting device) • Two kinds of forwarding 1. The destination address –based forwarding (when IP is used as a connectionless protocol) 2. Label-based forwarding (when the IP is used as a connection-oriented protocol) 5
- 6. FORWARDING BASED ON DESTINATION ADDRESS 6
- 7. Forwarding Techniques 1. 2. 3. 4. Next-Hop Method Network-Specific Method Host-Specific Method Default Method To make the size of the routing table manageable 7
- 8. Next-Hop Method • The routing table holds only the address of the next hop instead of information about the complete route 8
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- 15. • Example 6.2 Router R1 in Figure 6.8 receives a packet with destination address 192.16.7.14. Show how the packet is forwarded Solution The destination address in binary is 11000000 00010000 00000111 00001110. A copy of the address is shifted 28 bits to the right. The result is 00000000 00000000 00000000 00001100 or 12. The destination network is class C. The network address is extracted by masking off the leftmost 24 bits of the destination address; the result is 192.16.7.0. The table for Class C is searched. The network address is found in the first row. The next-hop address 111.15.17.32. and the interface m0 are passed to ARP 15
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- 19. Forwarding with Classless Addressing 19
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- 23. Address Aggregation • In classful addressing, there is only one entry in the routing table for each site outside the organization • In classless addressing, it is likely that the number of routing table entries will increase The increased size of the table results in an increase in the amount of time needed to search the table to alleviate the problem, the idea of address aggregation was designed 23
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- 25. Longest Mask Matching Packet arrives with dest. add.140.24.7.200 By longest mask matching correctly routed to Organization 4 The routing table is sorted from the longest mask to the shortest mask 25
- 26. STRUCTURE OF A ROUTER 26
- 27. Components performs the functions of the network layer 27
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