Consider a network in which for any two nodes directly connected with a link, amessage either reaches its destination within T time or gets lost.(a) Give an efficient handshake protocol for connection establishment for this networkbetween two nodes which are directly connected to each other.(b) Discuss the problems which may arise to the protocol in (a) if the two nodes arenot directly connected to each other.

Consider the arrangement of hosts shown in the Figure. All links are full-duplex, cantransmit up to 2Mbps, and all routers are faster and all routers are faster than theirlinks. A wants to send data to D at rate 1Mpbs and E wants to send data to F atrate 2Mbps. What is the throughput for A and E (how much data can they transferper sec) under the following conditions:(a) The congestion control policy at B employs a single input queue for data comingfrom both A and E and forwards using the FIFO discipline.(b) The congestion control policy at B employs separate input queues of equal sizefor A and E and forwards using round robin.Give reasons for your answers.

Consider the case where A is connected to B via a wired link and B is connected to C via a wireless link. The bandwidth of the link from A to B is 106 bytes/sec and for the link from B to C is 105 bytes/sec. The round trip delay is 1sec from A to B and 5 secs from B to C. Assume that A needs to send data to C using B as an intermediate hop. If a standard sliding window protocol is used from A to C, what would be the type of protocol used? If a split-TCP approach is used, what would be the types of protocol used.

Assume that you have a set of 4 nodes, A, B, C and D arranged in a ring with A asthe requester and B, C and D as responder. The execution proceeds in a sequenceof iteration. In each iteration, A asks a question which is to be sent in the clockwisedirection in the ring to all responders. On receiving this question, each responder senda response message back to A (which is again sent in the clockwise direction). Afterreceiving all of the responses, A proceeds with the next iteration by asking the nextquestion. You need to design a protocol stack to support this application. Describethe data link layer and routing protocol in sufficient detail for this protocol stack (e.g.,type of sliding window protocol, window size, routing strategy). The protocols mustbe efficient in terms of minimizing the execution/response time.

Consider the following protocol for public key distribution. There exists a centralauthority, CA, whose public key is known to everyone. If Bob wants to obtain Alice’spublic key, it sends a message containing the tuple, <PbCA(R), PbCA(Alice)>. to CA,where R is a random number, asking for Alice’s public key. In response,(a) CA sends the message containing the pair, <PrCA(R − 1), PrCA(PbAlice)>. Is itpossible to Trudy to attack this protocol and provide Bob with her public key insteadof Alice’s public key?(b) CA sends a the message <PbAlice(R − 1), PrCA(PBAlice)>. Is it possible to Trudyto attack this protocol and provide Bob with her public key instead of Alice’s publickey?