[e2e] Early FIN/close for query-response TCP connections like DNS's

[Stefanos Harhalakis]

Hello,

I'm somehow new to the list and I just read a large part of "TCP improved 
closing strategies?" thread that took place about a year ago (Aug 2009). After 
that I tested DNSSEC queries against some local DNS servers.

I found out this (and please, correct me if I'm wrong):

* Client connects
* Client queries
* Server responds
* Client closes
* Server closes

(Last two lines may be reversed (?))

>From what I understand, the FINs are problematic for this kind of traffic so I 
was wondering: Why not transform this to:

* Client connects
* Client queries
* Client closes
* Server responds
* Server closes

IOW: Since we know that this connection will have a Query and a Response, why 
not half-close the connection after the query is sent? This requires no 
modifications to TCP's behavior and will save at least RTT/2 because the 
server side will not wait for a FIN before closing. (no?)

Of course this approach can be generalized for all query/response sessions and 
more generaly, for cases where there is a "last query".