Re: [lwip-users] ARP during UDP transfers

[Elad Yosef]

In close matter, I have Peer-To-Peer Ethernet link in my target and
want to increase the ARP tables timeout.
Can it be done easily?

Elad

On Tue, Mar 29, 2011 at 5:39 PM, Roger Cover <address@hidden> wrote:
> Thank you for the quick reply. I thought that was the case.
>
> Regards,
> Roger
> -----Original Message-----
> From: address@hidden [mailto:address@hidden On Behalf Of Kieran Mansley
> Sent: Tuesday, March 29, 2011 8:25 AM
> To: Mailing list for lwIP users
> Subject: Re: [lwip-users] ARP during UDP transfers
>
> On Tue, 2011-03-29 at 08:14 -0700, Roger Cover wrote:
>> Greetings List,
>>
>> 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). My question is:
>> what is the appropriate method for my application to detect that this
>> has happened so it can ensure that no UDP packets are dropped in the
>> stack? I would prefer to have my application suspend its UDP
>> transmissions while the ARP traffic is being resolved.
>
> I don't think there is an easy way to detect this.  UDP is an inherently 
> unreliable protocol and provides no API to monitor loss.  ARP status is 
> entirely hidden from the application as there is no guarantee that your 
> application will be running on an Ethernet network.
>
> You could go some way to avoiding the ARP interrupting your transmissions by 
> making sure there is a valid entry for the destination before you try and 
> send to it, e.g. by sending a ping and waiting for a response.  You would 
> need to do this periodically in the absence of traffic from your application 
> as ARP entries will time out.
>
> Kieran
>
>
> _______________________________________________
> lwip-users mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/lwip-users
>
> _______________________________________________
> lwip-users mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/lwip-users
>