Re: [lwip-users] Establishing TCP Connection after power-up

[address@hidden]

farid mahini wrote:
> Question:  Since the SYN message has both source and destination 
> addresses (IP and MAC), why does MyServer request it? Wouldn't it get 
> added to ARP table as the SYN message travels up the stack to TCP layer.
You can configure lwIP to behave like that, but it's not a good idea to 
do so as it
a) is a security issue and
b) can have a large performance impact as every incoming packet leads to 
scanning the ARP table for a hit to update.

You should enable ARP_QUEUEING instead (define it to 1 in lwipopts.h) so 
that the outgoing SYN is buffered by lwIP until the ARP response is 
received. 1.4.0rc2 does this automatically.

Simon