Network Chapter 4 R2. What are the two most important network-layer functions in a datagram network? What are the three most important network-layer functions in a virtual circuit network? R14. Visit a host that uses DHCP to obtain its IP address, network mask, default router, and IP address of its local DNS server. List these values. R18. Suppose you purchase a wireless router and connect it to your cable modem. Also suppose that your ISP dynamically assigns your connected device (that is, your wireless router) one IP address. Also suppose that you have five PCs at home that use 802.11 to wirelessly connect to your wireless router. How are IP addresses assigned to the five PCs? Does the wireless router use NAT? Why or why not? P7. Suppose two packets arrive to two different input ports of a router at exactly the same time. Also suppose there are no other packets anywhere in the router. a. Suppose the two packets are to be forwarded to two different output ports. Is it possible to forward the two packets through the switch fabric at the same time when the fabric uses a shared bus? b. Suppose the two packets are to be forwarded to two different output ports. Is it possible to forward the two packets through the switch fabric at the same time when the fabric uses a crossbar? c. Suppose the two packets are to be forwarded to the same output port. Is it possible to forward the two packets through the switch fabric at the same time when the fabric uses a crossbar? P10. Consider a datagram network using 32-bit host addresses. Suppose a router has four links, numbered 0 through 3, and packets are to be forwarded to the link interfaces as follows: Destination Address Range Link Interface 11100000 00000000 00000000 00000000 through 0 11100000 00111111 11111111 11111111 11100000 01000000 00000000 00000000 through 1 11100000 01000000 11111111 11111111 11100000 01000001 00000000 00000000 through 2 11100001 01111111 11111111 11111111 Otherwise 3 a. Provide a forwarding table that has five entries, uses longest prefix matching, and forwards packets to the correct link interfaces. b. Describe how your forwarding table determines the appropriate link interface for datagrams with destination addresses: 11001000 10010001 01010001 01010101 11100001 01000000 11000011 00111100 11100001 10000000 00010001 01110111 P13. Consider a router that interconnects three subnets: Subnet 1, Subnet 2, and Subnet 3. Suppose all of the interfaces in each of these three subnets are required to have the prefix 223.1.17/24. Also suppose that Subnet 1 is required to support at least 60 interfaces, Subnet 2 is to support at least 90 interfaces, and Subnet 3 is to support at least 12 interfaces. Provide three network addresses (of the form a.b.c.d/x) that satisfy these constraints.