Computer communication queries

Tuesday, September 15, 2009
Q1. Why is multiplexing essential in data transmission and when exactly is it used in transmission?

Q2.Which is better tcpdump or Wireshark? and in what way?

From Cite Seer (CC2)
Rajani
Priyonath
Poonam
Masudur Rahaman

2 comments:

shivam said...

A1-Multiplexing refers to the ability to transmit data coming from several pairs of equipment (transmitters and receivers) called low-speed channels on a single physical medium (called the high-speed channel).A multiplexer is the multiplexing device that combines the signals from the transmitters and sends them over the high-speed channel. A demultiplexer is the multiplexing device via which the receivers are connected to the high-speed channel.
1.Frequency-division multiplexing

Frequency-division multiplexing, also called FDM, makes it possible to share the available frequency band on the high-speed channel by dividing it into a series of narrower-band channels so as to be able to continuously send signals coming from the different low-speed channels over the high-speed channel.
This process is used, in particular, on telephone lines and twisted-pair physical connections to increase the data rate.
2.Time-division multiplexing

In time-division multiplexing, also called TDM, the signals from the different low-speed channels are sampled and transmitted successively on the high-speed channel by allocating each channel in turn all of the bandwidth, even if it does not have any data to transmit.
3.Statistical multiplexing

Statistical multiplexing is similar to time-division multiplexing except that it only transmits low-speed channels that actually have data on the high-speed channel. The name of this type of multiplexing comes from the fact that the multiplexers base their behaviour on statistics concerning the data rate of each low-speed channel.
Since the high-speed line does not transmit the empty channels, performance is better than with time-division multiplexing.BY SHIVAM DUBEY(SUDANSHU TEAM)CC19.

Unknown said...

actually we can not say which one is better , but it better we capture the packet with tcpdump rather than wireshark , when you want do REMOTE CAPTURING and do not want the network load associated with running Wireshark remotely .
But totally work with wireshark is easier than tcpdump because of GUI in wireshark .

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