Re: [lwip-users] ARP during UDP transfers

[Simon Goldschmidt]

Roger Cover <address@hidden> wrote:

> After researching the source code for a while I have determined that lwIP 
> will queue one UDP packet when the ARP table entry for its destination times 
> out, and then drop subsequent UDP packets until the ARP reply is processed (I 
> have ARP_QUEUEING set to 1).

Actually, the code always queued a number of packets, not only one. Now (since 
1.4.0RC1 I think) it queues one packet (the latest) if ARP_QUEQUEING is 0 
(which is kind of mandatory from the RFC) and a number of packets if it is 1. 
If it is set to 1, the number of packets queued is defined by 
MEMP_NUM_ARP_QUEUE, I think. In your case, just set it high enough, depending 
on your application protocol, the number of simultaneous connections and the 
expected timeout to receive the ARP response.

Simon