Re: Window Scale option

[[e-mail]]

Dave,

Hmmmm.  It seems clear in retrospect that a host really wants to allow
its applications to dynamically adjust the amount of receive buffering
they can have, and thereby possibly adjust the window scaling.  I
wonder if it's too late to do that, or whether it has to await a
"second generation TCP".  I recall that Van believed that the window
scale ought to be determined in the Syn exchange, but I don't recall
his argument for it.

I expect the main problem is reliable transmission of the R value in
ACK segments.  I can imagine something like this: Once the 3 way
handshake has negotiated scaling, any data/ACK packet can carry
ScaleOption(S,R).  If I want to change my R to R', I start sending a
receive window with the R' scaling, together with ScaleOption(S,R').
Once the other side echos R' in its ScaleOption(R',S), I can stop
sending the option.  This is obviously more complicated than the
current window scaling scheme, but it would at least support what
applications really want.

I suppose I should have reviewed the TCPLW archives before sending this
message...

Bob Braden