Chapter 24 TCP Futures and Performation

TCP has operated for many years over data links ranging from 1200bit/sec dialup SLIP links to Ethernets.

In Section 2.9 we described the concept of the path MTU. It is the minimum MTU on any network that is currently in the path between two hosts.

Big Packets or Small Packets

In Section 20.7 we showed the capacity of a connection as XXXXXXX and called this the bandwidth-delay product. This is also called the size of the pipe between the end points.

Gigabit Networks

Then window scale option increases the definition of the TCP window from 16 to 32 bits . Instead of changing the TCP header to accommodate the lager window,the header still holds a 16-bit value, and an option is defined that applies a scaling operation to the 16-bit value. TCP then maintains the "real " window size internally as a 32-bit value.

The timestamp option lets the sender place a timestamp value in every segment . The receiver reflects this value in the acknowledgment , allowing the sender to calculate an RTT for each receiver ACK.

TCP provides a virtual-circuit transport service.There are three distinct phases in the life of a connection: establishment , data transfer , and termination .

Published numbers in the mid-1980s showed TCP throughput on an Ethernet to be around 100,000 to 200,000 bytes per second .