02-05-2012, 05:30 PM
COMPANY PROFILE SYNOPSIS
The TCP congestion control is implemented primarily through algorithms operating at end systems.
It does not prevent congestion collapse from undelivered packets.
To prevent the congestion collapse and unfairness created by applications that are unresponsive to network congestion, a congestion-avoidance mechanism called “Network Border Patrol” (NBP) is proposed.
NBP checks the exchange of feedback between routers at the borders of a network in order to detect and restrict unresponsive traffic flows before the packets enter the network.
Thus it prevents congestion within the network.
Existing system
vIt uses TCP congestion control algorithm which is implemented at the end of the sender and receiver systems.
vBut it suffers from two problems
üCongestion collapse from undelivered packets
üUnfair allocation of bandwidth
DRAWBACKS
qUndelivered packets are not retransmitted. So, it does not ensure no loss of data.
qUnfair bandwidth allocation arises in the Internet due to the presence of undelivered packets.
qAlso even after the packets has entered the networks they are not checked for unresponsive traffic flows. So, traffic increases.
PROPOSED SYSTEM
vNBP is a congestion avoidance mechanism, which allows routers on the borders of the network to perform and maintain per-flow rate.
vThree important of the NBP mechanism:
ØThe architectural components, the modified edge routers, which must be present in the network.
ØThe Feedback control algorithm, which determines how and when information is exchanged between edge routers.
ØThe Rate control algorithm, which uses the information carried in feedback packets to regulate flow transmission rates and thereby prevent Congestion collapse in the network.
MERITS
ØBuffering of packets is carried out in the edge routers rather in the core routers.
ØThe packets are sent into the network based on the capacity of the network and hence there is no possibility of any undelivered packets present in the network.
ØAbsence of undelivered packets avoids overload due to retransmission.
ØFair allocation of bandwidth is ensured.