Question:
Suppose 5 TCP connections are present over some bottleneck link of rate X bps. All connections have a huge file to send (in the same direction over the bottleneck link). The transmissions of the files start at the same time. What is the transmission rate that TCP would like to give to each of the connections?
How to identify a UDP socket? How to identify a TCP socket? Are these data fields same? Why?
UDP and TCP use 1''s complement for their checksums. Suppose you have the following three 8-bit words: 01010100, 01111000, 10001100. What is the 1''s complement of the sum of these words? Show all work. Why UDP takes the 1''s complement of the sum, that is, why not just use the sum?
Suppose Client A initiates a Telnet session with server S. Provide possible source and destination port numbers for:
a. The segment sent from S to A. b. The segment sent from A to S.
Compare two pipelining protocols shown in the textbook - go-back-N and selective repeat.
In our textbook, protocol rdt 3.0 shows a data transfer protocols that uses only acknowledges. As an alternative, consider a reliable data transfer protocol that uses negative acknowledgements. Suppose the sender sends data only infrequently. Will a NAK-only protocol be preferable to protocol that uses ACKs? Why? Suppose the sender has a lot of data to send and the end-to-end connection experiences few losses. In the second case, would a NAK-only protocol be preferable to a protocol that uses ACKs? Why?
Let us assume that the roundtrip delay between sender and receiver is constant and known to the sender. Would a timer still be necessary in protocol rdt 3.0, assuming that packets can be lost? Please explain.
Briefly discuss the basic mechanisms adopted by TCP congestion control.
Describe two major network-layer functions in a datagram network.
Describe how packet loss can occur at input and outputs of a router. Is it possible to eliminate packet loss at these ports? If so, how? If not, please explain.
Suppose an application generates chunks of 360 bytes of data every 20 msec, and each chunk gets encapsulated in a TCP segment and then an IP datagram. What percentage of each datagram will be overhead, and what percentage will be application data?
Consider a datagram network using 8-bit host addresses. Suppose a router uses longest prefix matching and has the following forwarding table:
Prefix Match Interface 11 0 110 1 otherwise 2
For each of the 3 interfaces, give the associated range of destination host addresses and the number of addresses in the range.
Consider the following network. With the indicated link costs, use Dijkstra's shortest-path algorithm to compute the shortest path from x to all network nodes. Show how the algorithm works by computing a table similar to the textbook example. In cases when several candidate nodes have the same minimal costs, choose a node according to its alphabetical order.
Consider the count-to-infinity problem in the distance vector routing. Will the problem occur if we decrease the cost of a link? Why?
IPv6 adopts a fixed-length 40 byte IP header. What is the major advantage of this approach compared to that in IPv4?
Suppose an ISP owns the block of addresses of the form 200.200.128.0/20. Suppose it wants to create four subnets from this block, with each block having the same number of IP addresses. What are the prefixes (of form a.b.c.d/x) for the four subnets?
Why are different inter-AS and intra-AS protocols used in the Internet?
JAVA - COMPLETE CODE ESTIMATE
Sending Email with Java
Java provides an API for interacting with the Internet mail system, which is called JavaMail. However, we will not be using this API, because it hides the details of SMTP and socket programming. Instead, you should write a simple Java program that establishes a TCP connection with a mail server through the socket interface, and sends an email message.