Re: [lwip-users] tcp_output_segment() "silly window avoidance" shrinking the window is "strongly discouraged" and "SHOULD NOT"?

[Kieran Mansley]

On Fri, 2007-06-15 at 18:17 +1000, Tom Evans wrote:
> This may be a bug. I'd be interested in other opinions. If anyone has a
> copy of "TCP Illustrated" it may be worth checking this in there.

> The window should only shrink "naturally" (because of incoming data).
> SWS Avoidance delays the window OPENING until it can be opened EITHER to
> the MSS or to half of the receive buffer size. The lwIP code is only
> performing the former comparison.

Looks like a bug to me.  Could you file a bug report on savannah?

> The second (obvious) problem would happen if someone did the following
> in lwipopts.h while trying to save memory or buffers:
> 
>     /* TCP Maximum segment size. */
>     #define TCP_MSS                 512
>     /* TCP receive window. */
>     #define TCP_WND                 500

I'd call that a mis-configuration.  It should probably be documented
however.

Kieran