clarify that INITCWND caps amount of data sent to a server before address validation

[kazuho]

Clarifies how we prohibit a server from sending too many packets to a client prior to validating the address.

Closes #2135.

[martinthomson]

I think that you have this backwards. The point here is that the client is limited by INITCWND. The server has to abide by the x3 rule.

[kazuho]

@martinthomson That's definitely true. Addressed in f7b0187.

[marten-seemann]

I'm not sure if this is correct. If a packet is declared lost, it can be retransmitted, so in that case the amount of data sent is larger than initial cwnd.

[kazuho]

@marten-seemann That's a good point. Does changing the text to refer to "congestion avoidance algorithm" instead of "initial congestion window" resolve the concern?

[martinthomson]

This looks fine, but I have a new concern: this makes it appear as though the congestion window doesn't apply to the server. It does. Would this be better?

The amount that servers are permitted to send is also constrained by the limit set by the congestion avoidance algorithm. Clients are only constrained in what they can send prior to address validation by congestion control.

[kazuho]

@martinthomson Thanks. Applied in 5522bd5.

[ianswett]

Suggestion: "In addition to sending limits imposed prior to address validation, servers are also constrained in what they can send by the limits set by the congestion avoidance algorithm. Clients are only constrained by the congestion avoidance algorithm."

[janaiyengar]

s/congestion avoidance algorithm/congestion controller.

[kazuho]

@ianswett @janaiyengar Thank you! Applied the suggestions.

[martinthomson]

Thanks everyone. This looks nothing like what it did when it started, but it's much clearer as a result.