An Investigation into Transport Protocols and Data Transport ...

7.1. Metrics 140
higher throughput achieved by the lower latency flow.
Also, under symmetric network conditions, two flows when perfectly synchronised
and experiencing the same end-to-end latencies, should have a
fairness of unity for all environments.
It is therefore important to investigate the effects of RTT unfairness between
New-TCP algorithms such that long latency flows do not experience
severe unfairness because of the increased aggressiveness of shorter latency
flows.
7.1.5 Friendliness
The deployment of New-TCP is unlikely to be sudden, and therefore gradual
deployment whereby New-TCP algorithms have to co-exist with Standard
TCP on the Internet is expected. As such, the dynamic between New-TCP
stacks and legacy Standard TCP should be studied.
New-TCP algorithms should be able to utilise spare capacity of the network;
however, it should also not starve legacy TCP flows of bandwidth.
Conversely, in low-speed networks, they should share bandwidth fairly with
legacy TCP.
Therefore, define friendliness to be (the value of) the fairness metric, F i,j
when the i th flow is that of Standard TCP.
7.1.6 Overhead
Loss based congestion control algorithms must generate packet loss in order
to probe for free bandwidth. The increase in the rate of probing will increase
the number of congestion epochs per unit time, and as a result, the rate of
packet loss also increases. This is especially important as the large number