1. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Network Layer Protocols: Unicast and Multicast Routing Protocols 21.1 Unicast Routing 21.2 Unicast Routing Protocols 21.3 Multicast Routing (IGMP)

2. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 21.1 Unicast Routing Metric Interior and Exterior Routing Internet is enormous. No protocol can update all routers. Need to divide into autonomous systems (AS): Routing inside AS = Interior routing Routing outside AS = Exterior routing

3. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 21.1 Unicasting Metric = a cost for passing through a network 11 1 11 Cost metric: 1 (hop count), delay, throughput delay

4. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 In unicast routing, the router forwards the received packet through only one of its ports. Note:

5. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 21.2 Unicast Routing Protocols Figure 21.2 Popular routing protocols Routing Information Protocol Open Shortest Path First Border Gateway Protocol

6. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 21.3 Autonomous systems Interior and Exterior routing protocols Other routers use only interior routing protocols

7. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Table 21.1 A distance vector routing table Destination Hop Count Next Router Other information 163.5.0.07172.6.23.4 197.5.13.05176.3.6.17 189.45.0.04200.5.1.6 115.0.0.06131.4.7.19 Routing Information Protocol Cost metric: 1 (hop count)

8. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 21.4 Example of updating a routing table No hop count improvement, do not change

9. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 21.7 Areas in an autonomous system Cost metric: delay, throughput Open Shortest Path First Idea: Router must have exact internet topology Link state routing: 1. Share info of neighborhood 2. Share info with every router 3. Share info when change detected

10. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Sample Internet and Graphical Representation

11. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 21.20 Shortest-path calculation Dijkstra Algorithm

12. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Table 21.2 Link state routing table for router A NetworkCostNext RouterOther Information N15 N2 7C N310D N411B N515D

13. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Table 21.3 Path vector routing table NetworkNext RouterPath N01R01AS14, AS23, AS67 N02R05AS22, AS67, AS05, AS89 N03R06AS67, AS89, AS09, AS34 N04R12AS62, AS02, AS09 Border Gateway Protocol Path Vector Routing: 1. Uses paths of ordered AS

14. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 21.21 Path vector messages

15. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 21.3 Multicast Routing IGMP IGMP: Internet Group Management Protocol One-to-Many Commmunication Source: Unicast Address (Class A, B or C) Destination: Multicast address (Class D)

16. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 In multicast routing, the router may forward the received packet through several of its ports. Note:

17. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 IGMP is a group management protocol. It helps a multicast router create and update a list of loyal members related to each router interface. Note:

18. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 21.25 IGMP message format

19. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Table 21.4 IGMP type field TypeValue General or special query0x11 or 00010001 Membership report0x16 or 00010110 Leave report0x17 or 00010111

20. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 21.26 IGMP operation Mutually exclusive addresses

21. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 21.27 Membership report 0x16 Multicast address

22. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 In IGMP, a membership report is sent twice, one after the other. Note:

23. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 21.28 Leave report No Response

24. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Monitoring membership checks if groups are still active or not, by sending a general query message. The general query message does not define a particular group (group address 0.0.0.0). Note:

25. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Figure 21.29 General query message No Response

26. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Example Imagine there are three hosts in a network, as shown in Figure 21.30 (below). A query message was received at time 0; the random delay time (in tenths of seconds) for each group is shown next to the group address. Show the sequence of report messages.

27. McGraw-Hill©The McGraw-Hill Companies, Inc., 2004 Solution The events occur in this sequence: 1.Time 12. The timer for 228.42.0.0 in host A expires and a membership report is sent, which is received by the router and every host including host B which cancels its timer for 228.42.0.0. 2.Time 30. The timer for 225.14.0.0 in host A expires and a membership report is sent, which is received by the router and every host including host C which cancels its timer for 225.14.0.0. 3.Time 50. The timer for 251.71.0.0 in host B expires and a membership report is sent, which is received by the router and every host. 4.Time 70. The timer for 230.43.0.0 in host C expires and a membership report is sent, which is received by the router and every host including host A which cancels its timer for 230.43.0.0.