CS610 -Computer Network GDB No. 01 Ideal Solution Fall 2014 Due Date 6th August 2014

[vuassignments]

CS610 -Computer Network GDB No. 01 Solution and Discussion Fall 2014 Due Date:August 06, 2014


Graded Discussion:

“For communication across Internet, TCP/IP protocol suit is used for achieving universal services and routers are used to connect different networks. TCP is one of the major transport protocol used in TCP/IP protocol suit which provides reliable data delivery service to applications.
Suppose two applications use TCP to establish a connection, communicate, terminate the connection, and then open a new connection. Further suppose a FIN message sent to shut down the first connection is duplicated and delayed until the second connection has been established”.

Requirements:
a. If a copy of the old FIN is delivered, will TCP terminate the new connection? Why or why not?
b. Can a router send request to another router for TCP connection? Give reason.

A concise, coherent and to the point comment is preferred over lengthy comment having irrelevant details. Your comments must not be more than 2-3 lines in each part. Comments, posted on regular Lesson's MDB or sent through email will NOT be considered in any case. Any request about such an acceptance will not be catered.

[Vuhelper]

Suppose a FIN message, sent to shut down the first connection btw two machines on Internet, is duplicated and delayed until a second connection btw the same two machines has been established. If a copy o f the old FIN is delivered, will TCP terminate the new connection?

Answer: No

The message for the new TCP connection would be required to have identical source & destination IP addresses, protocol port numbers and TCP sequence numbers for the earlier message to have an effect.

The host waits 2 * max_segment_life time before reallocating the port from the old connection.
Most of the s/w implementation of TCP allocate sequence number depending upon the system clock time, which will be different for two subsequent messages.

[vuassignments]

Ans to part 1:

TCP uses a port. A port is identified for each address and protocol by a 16-bit number, commonly known as the port number. The port number, added to a computer's IP address, completes the destination address for a communications session. That is, data packets are routed across the network to a specific destination IP address, and then, upon reaching the destination computer, are further routed to the specific process bound to the destination port number.

So,a copy of the old FIN will not be able to terminate the new connection as port number in new connection will be different.

Ans to part 2:

No, a router can not send request to another router for TCP connection?

Reason:
TCP connections are for communication between applications but routers do not run applications.