Re: [lwip-users] MSS Configuration Difficulty

[address@hidden]

Am 14.02.11 15:30, schrieb address@hidden:
> What I'm unsure of is whether the IP fragmentation code can tolerate
> this misconfiguration of the MTU, or whether there is likely an error
> in the fragmentation code, or perhaps in one of our drivers.
The MTU is correct (set to 1500), only the MSS is "misconfigured". 
However, this is exactly what the IP fragmentation code should do: split 
packets that are too long into multiple packets of correct size. It's a 
bit odd to configure the stack in a way that every outgoing packet has 
to be processed, but it shouldn't break it.

Therefore, I'm with Kieran to suspect the problem being either a bug in 
lwIP which is already fixed or in your driver or port, since I haven't 
seen such a problem, yet.

BTW, regarding the optimal MSS setting: 1460 is the one you'll want. The 
TCP code takes care of leaving room in the segments if options are 
required so that data + options == 1460.

Simon