TCP Friendly

By Raul Bernardino

Introduction:

It is becoming a general concerns about the using of the bandwidth over the networks or internet. For instance the networks users are making a lot of video or audio streaming over the internet, then the UDP will be occupied or used almost all of the network resources and it comes to the networks congestions.

In order to overcome the network congestion, the TCP-Friendly becomes to play the important roles on how to manage the congestions in the network.

The TCP segment structure as in below picture:

How TCP Works as in the below picture:

 The sequence numbers (seq. #s) are the byte stream of the 1^st segment of the data (packet).

The ACKs are the accumulative of ACK and the seq # of the next bytes that expected from the other end.

What is the congestion? The congestion is an overflow network where too much data and faster transmission from the sender and network can’t handle. The consequence is packet lost and long delay of the transferred.

The TCP congestion control on the bandwidth probing: it is increasing the transmission rate on the receipt ACK until the loss packets occur then it is slowing down the transmission rate. As it shows below picture:

There are several studies and researches out there to overcome the network congestions. For instance:

a)     Sisalem, D., Emanuel,F. and Schulzrinne, H. used “Direct Adjustment Algorithm (DAA) to create and adaptive transmission rate in network congestion especially for multimedia application. The control is relaying on the RTP”

b)    Padhye, J., Kurose,J., Towsley, D.,  and Koodli, R. used congestion control algorithm for the Unicast  trafficking by revising the TCP-friendly equation version. In their found, the algorithm is focusing on the roundtrip time. If the packets are lost in between the roundtrip time then the send set the rate otherwise the sender double up the initial rates to send

c)     Tan,W. and  Zhakor, A. (Oct. 1999) from University of California, Berkeley where allow users to subscribe and it is driven by hierarchical FEC data, the formula approach will we determine the availability of the bandwidth

d)    Floyd,S., Handley, M.,  Padhye, J., and Widmer, J. (Mar. 2000) proposed congestion control relaying on the unicast traffic.  “This mechanism provides responsive to continual congestion, to avoid unnecessary fluctuations, to avoid the opening of needless noise, and the robustness over a wide range of timescales”

Conclusion: All researchers are willing to optimize the bandwidth with several equations based on the networks congestion control. In the future, it is still not has a clear idea on how it will be developing and managing the internet architecture and internet bandwidth. If the cost of the bandwidths are cheap then every agencies will be creasing the bandwidth which is bigger than their own demands without have to manage the bandwidth.

References list:

1.     Floyd S, (2008), TCP Friendly Rate Control (TFRC), University College London, [online]. Available from: http://www.icir.org/floyd/papers/rfc5348.pdf, (Accessed date: August 20, 2011)

2.     Wang Q., et all (n.d.) TCP-Friendly Congestion Control Schemes in the Internet,  [Online]. Available from:http://www.sics.se/~runtong/11.pdf (Accessed date: August 20, 2011)

3.     Hierarchical FEC (HFEC), [online]. Available from: http://www-video.eecs.berkeley.edu/~dtan/icip99slide.pdf (Accessed date: August 20, 2011)

4.     Equation-Based Congestion Control for Unicast Applications: The Key TFRC Documents, [online]. Available from: http://www.icir.org/tfrc/ (Accessed date: August 20, 2011)