Re: [tcpm] timestamp options (was Re: New Version Notification for draft-touch-tcpm-tcp-edo-01.txt)

["Scharf, Michael (Michael)" <[e-mail]>]

> For late TS, we would still need at least 2 Bytes during
> <SYN>/<SYN,ACK> to allow that capability.
> 
> However, as the useful values of Window Scale only cover 0..14 [1], one
> approach to save SYN option space would be to negotiate up to 4 binary
> (on/off) plus WS in a new single 3-byte option.

I might be wrong, but I've thought so far that "replacing" the window scale option would be pretty difficult. We already had reports of middleboxes that parse this option because they try to understand rwnd (or they do not parse the option even if they should, or they have entirely broken logic to mess up TCP...). I think one example are firewalls that try to detect whether segments are in-window. Another example could be PEPs that try to tune rwnd (if they still exist in the wild).

My understanding so far was that a solution only for timestamps would be the most low-hanging fruit.

Michael