Subject: Re: Window Scale option

From: [email-masked]
Date: Tue, 5 May 1998 12:12:53 -0700

*> 
  *> The SYN only restriction is far more problematic for the timestamp
  *> option than it is for than the window scale option.
  *> 
  *> For example, if you have a laptop with a radio modem and a 100bT
  *> interface, you are likely to find that you are either wasting the
  *> skinny link with uncompressible timestamps, or underfilling the LAN
  *> because you didn't negotiate timestamps.  Although you could implement
  *> per-route or per-interface flags to control TCPLW features, the real
  *> problem is the pervasive 1323 mindset that new options must never
  *> appear after the SYN-ACK.

Matt,

I would not call it a "mindset", I would call it concern about
(possible lack of) interoperability.  However, the issue of breaking
some TCPs with options on non-SYN segments may well be less of a
concern than it was 8 years ago.

In any case, I see no reason why TCPs cannot exchange timestamp options
n the SYN exchange to enable the feature, then suspend sending
time stamps whenever they want (e.g., when the connection throughput
falls below some threshold?)  Am I missing something?

Bob

---

From: Matt Mathis <[email-masked]>
Date: 05 May 1998 16:01:19 -0400

>falls below some threshold?)  Am I missing something?

I considered this approach, but the difficulty is that there is no
distiction between "timestamp" and "timestamp reply".  Thus turning
off timestamps requires having some way to discover that the other end
isn't using them.  For example the value zero could be used to indicate
that a reply is not needed.

I have long since forgotten the details....

--MM--