Subject: Window scale factor ?

From: "Padmapriya Parthasarathy" <[email-masked]>
Date: Fri, 11 Dec 1998 14:04:52 PST

According to RFC1323, the maximum value for ws is 14. If TCP did
not use signed arithmetic (all SEQ_XX macros are signed)
for detecting old/new data and used unsigned arithmetic with
proper wraparound checks, would the value for ws be 15 ?

Thanks
Priya

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---

From: David Borman <[email-masked]>
Date: Fri, 11 Dec 1998 17:33:52 -0600 (CST)

> From: "Padmapriya Parthasarathy" <[email-masked]>
> Subject: Window scale factor ?
> Date: Fri, 11 Dec 1998 14:04:52 PST
>

No.  Think of the sequence space as a circle.  The 1/2 of the
circle ahead of any given point is the upcoming data, the 1/2
of the circle behind it is the old data.  You don't want to
advertise a window of all the new data, because then you are
butting right up agains the old data.  So, you limit the window
to 1/2 of the upcoming data, or 1/4 of the total sequence space.
That give you a maximum window shift of 14.

			-David Borman, [email-masked]