LECTURE #9
Transport Layer
oResponsible for Source-to-Destination delivery of Entire Message
oNetwork Layer oversees source-to-destination delivery of the entire packets but it
does not recognize any relationship b/w those packets
oNetwork layer treats each packet independently
oTransport Layer ensures that whole message arrives at the destination intact
xFunctions of Transport Layer
oService Point Addressing
¾Computers run several programs at the same time
¾Source-to-Destination delivery means delivery not only from only from one
computer to the other but also from a specific process on one computer to a
specific process on the other
¾Transport layer header includes a type of address called Service Point Address
or PORT Address
¾Network layer each packet to the correct computer while Transport layer gets
entire message to the correct process on that comuter
oSegmentation and Reassembly
¾Message is divided into transmittable segments
¾Each segment contains a sequence number
¾These sequence no.s enable Transport layer at the receiving m/c to reassemble
message correctly at the destination and to identify and replace lost packets
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