1. Describe a protocol combining the sliding windows algorithm with selective ACKs. Your protocol should retransmit promptly, but not if a frame simply arrives one or two positions out of order. Your protocol should also make explicit what happens if several consecutive frames are lost.

2.

a			F
Node	cost	nexthop	node	Cost	nexthop
B	1	B	A	3	E
C	2	B	B	2	C
D	1	D	C	1	C
E	2	B	D	2	E
F	3	D	E	1	E

Table 1

Suppose we have forwarding tables shown in Table 1 for nodes A and F, in a network where all links have cost 1. Give a diagram of the smallest network consistent with these tables.

3. a. Describe the states diagram for the following Convolution Code. The initial state is 00. (The comma separator is for convenience, it is not part of the string):

b. What is the code for the input: 0010?

c. What is the original code (with high probability) of the received string:

11 10 10 11 00 ?

4. a. Which fields in IP header should be identical for IP fragments built from the same IP packet?

b. Assume that a packet was IP fragmented to 3 chunks. Describe an efficient way to calculate the amount of the data sent by the transport level protocol in this packet.

c. When a minimum-size IP datagram travels across an Ethernet, how large the frame?

d. A computer receives its IP from a DHCP server. Is this computer suitable to be a server? If yes, how clients could connect to it.

5. a. How sending IP packets to nonexistent address on a remote Ethernet can generate excess broadcast traffic on the network.

b. Will be a switch more efficient in handling IP multicast traffic than a HUB? Find information about IGMP snooping option and explain what this option does. If you develop an IP phone application with “conference call” feature for local networks connected by a HUB would you prefer usage of Unicast, Broadcast or Multicast. Pls, explain why.