Section 15.6. Exercises

15.6. Exercises

1.	For sending a message from a point to multiple points, compare the trade-offs of using multiple unicast connections, and using any multicast approach, such as DVMRP, explained in this chapter.
2.	Discuss the efficiency of MOSPF if the sparse-mode algorithm is used.
3.	Consider Figure 15.5, and assume that we want to implement MOSPF from a server in LAN 1 to a multicast group of five members, three group members in LAN 3 and the two others in LAN 4. Also assume that the cost of each link is indicated by the sum of two ending routers' subscripts. For example, the cost of link R 3 to R 8 is 11. If a router ends a LAN, the cost of its associated link is assumed to be 1. Show the cost of all links on the network. Form the least-cost tree for this multicast action, and find the root of copying routers.
4.	To optimize the routing delay in a sparse-mode PIM: Find the optimal place for the rendezvous point. Give an example of a spanning tree, and justify your answer.
5.	Consider Figure 15.6, and assume that we want to implement sparse-mode PIM from a server in LAN 1 to a multicast group of five members, with three group members in LAN 3 and the two others in LAN 4. Also assume that the cost of each link is indicated by the sum of two ending routers' subscripts. For example, the cost of link R 3 to R 8 is 11. If a router ends a LAN, the cost of its associated link is assumed to be 1. Find a reasonably good location for the rendezvous point for this multicast action. Form the least-cost tree for this multicast action, and find the root of copying routers.
6.	Repeat exercise 5, but this time use the CBT protocol.
7.	In Figure 15.16, five LANs, 1 through 5, are networked through their associated routers, R 3 , R 8 , R 6 , R 5 , and R 1 . The cost of each link is indicated in the figure. A server in LAN 1 wants to send messages to the indicated multicast group. For deploying the MOSPF protocol, find the multicast tree. For deploying the sparse-mode PIM protocol and using the same tree you obtained in part (a), find the location of the rendezvous point and its associated costs to each multicast group member. Figure 15.16. Exercise 7 example for multicast protocols
8.	For a global number of copies F = 7, use the tree-based multicast algorithm in a B 16,2 copy network, and show details of stage-by-stage copying.
9.	Three major Internet service provider domainsISP 1, ISP 2, and ISP 3 are connected through three border routers: R10, R20, and R30, respectively, as shown in Figure 15.17. All three ISPs agree to use MSDP for interdomain multicasting. Each domain has selected a router as its ISP MSDP representative, which can also be used as a rendezvous point, if needed. A source in ISP 1 wants to multicast messages to three groups located in various geographical locations, as shown. ISP 1 uses MOSPF, and IPS 2 and ISP 3 use sparse-mode PIM for intradomain multicasting. The cost of each link (equal in both directions) is indicated in the figure. Indicate all the involving routers in ISP 1, and find the total multicast cost to LAN 1 and LAN 2. Indicate all involving routers in ISP 2 and find the total multicast cost to LAN 3 and LAN 4. Indicate all involving routers in ISP 3 and find the total multicast cost to LAN 5. Figure 15.17. Exercise 9: using MSDP for interdomain multicasting and MOSPF and sparse-mode PIM protocols for intradomain multicasting
10.	For a global number of copies F = 7, use the Boolean splitting multicast algorithm in a D 16,2 copy network. Output ports 1, 2, 3, 7, 10, 12, and 15 receive a copy of packet. Show details of stage-by-stage copying. Compare the tree-based multicast algorithm with the Boolean splitting multicast algorithm in terms of speed and performance.
11.	We want to show the copying mechanism in the switch fabric of routers whose global number of copies F = 5. The switch fabric is an Omega network 8,2 that has r = 6 stages. Use the Boolean splitting multicast algorithm. Output ports 1, 2, 4, 5, and 7 receive a copy of the packet. Show the details of stage-by-stage copying. Use the tree-based multicast algorithm to make five copies of a packet, and show the detail of stage-by-stage copying.
12.	Consider a small switch fabric of 4 x 4 crossbar. Design the multicasting portion of its input port processor. Present all the hardware details.
13.	Computer Simulation Project . Use the computer program you developed for the simulation of the seven-node network in Chapter 7 and modify it to model the network shown in Figure 15.16. Simulate a sparse-mode PIM for multicasting from router R 1 to four recipients located in a multicast group spread over a wide geographic area. Construct a multicast group. Write a computer program to do a sparse-mode multicast tree. Assign a rendezvous point. Demonstrate the formation of four packet copies made for the multicast group.