I assume you were reading the original LWIP documentation PDF from Adam Dunkel. Some parts of it are very out of date.
IP fragmentation and reassembly has been supported for a long time (at least back to LWIP 1.1.1, which is where I started using LWIP).
There are options for whether the fragmentation and reassembly code is enabled: IP_FRAG and IP_REASSEMBLY. You can turn them off to reduce overhead if you don't need them in your application.
The reassembly buffer mechanism changed at some point between 1.1.1 and 1.3.2. It used to be a static buffer but it now works directly with pbuf chains.
----- Original Message -----
Sent: Thursday, January 21, 2010 7:20 PM
Subject: [lwip-users] IP layer - fragmentation and reassembly
Hi All,
I was reading the lwip documents and come to know that IP layer wont handle the sending and receiving the fragments. Does this feature supported currently (1.3.2) or still not?