[e2e] ECN questions

[Guy Kaminitz]

Hi,

I have a few questions about your documents regarding ECN:

1. Quoting rfc3168 page 18 paragraph 2: "TCP should not react to congestion indications more than once every window of data" but what if the TCP sender is in the fast recovery state, and receives a CE notification? (in the same window or after the first window of data) , do they mean one RTT, when they wrote "window of data" ?

2. How should TCP deal with a CE in a fast recovery state, after receiving several partial acknowledgments? Should the TCP reduce the congestion window, or not to take the CE in account?

3. in RFC 3168 section 6.1.2(the TCP sender) at the end of the second paragraph "however, if any retransmitted packets are dropped, then this is interpreted by the source TCP as a new instance of congestion" , my question is how does the sender know that the retransmitted segment is lost, does it wait to the retransmission timer or several duplicate acknowledgments ? if so, the sender will not decrease the cwnd in approximately one round trip time any way ?

4. Does anyone familiar with a NewReno TCP source code that supports ECN ? In addition, where can I get it?

I'll be happy to receive comments and remarks about these small questions.

Thanks Guy,