Windows Scaling
Do both sides of a TCP communication have to allow windows scaling (tcp.option_kind ==3) for scaling to take affect? Or can one side support it and the side other not?
thank you.
Request for Comments: 1323 TCP Extensions for High Performance
This option is an offer, not a promise; both sides must send
Window Scale options in their SYN segments to enable window
scaling in either direction.
Article with graphs here mentions that setting the scale factor to 1 (2^0) allows it to be "supported" without having to allocate extra memory.
This is why sometimes you will see one side of the connection (usually whoever is sending the bulk of the data) offer the Window Scale option, but use a scale factor of 0. This means "Hey, I am offering this option so that you can use your window scale on your side, but I'm not going to use a multiplier on my end. You can, but I'm just going to let my advertised window be what it is."
But if both sides don't offer, then the option cannot be used as ChuckC mentioned.
Asked: 2020-07-20 19:15:19 +0000
Seen: 396 times
Last updated: Jul 22 '20
The Wiki page has been updated with an example.