[Iccrg] Fairness VS Friendliness

[WangYaogong]

Hi,
 
I'm somewhat confused about the similarities and differences between the concepts of fairness and friendliness. Sometimes they seem to be equivalent, but sometimes not. For example, a TCP-friendly protocol may not be fair to TCP in all conditions. It may occupy much more bandwidth than TCP in large BDP networks where TCP cannot make full use of the high speed.
 
According to my understanding, I define Fairness and Friendliness as follow:
 
Fairness: On a path with a single bottleneck, two competing long-lived flows with the same RTT should achieve approximately the same average throughput. We can use Jain's Index to measure it.
 
Friendliness:  A is said to be friendly to B if:
when coexisting with B, A will not decrease the speed of B in any setting ( i.e. B gets as much bandwidth competing against A as it would competing against with another B flow)
We may use the bandwidth stolen by A from B, divided by B's original bandwidth, to measure it.
 
Is my understanding correct? Thanks.
 
Yaogong
 
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