[lwip-users] Delay at startup to answer with gateway

[Stéphane Lesage]

Hi,

My LwIP devices work fine in general,
but I discovered a problem recently in an environment where we use gateways.

After powering-up, we have a delay of about 35 seconds before they are 
reachable.
When using the same device from the same network, we have no problem.
At first I suspected a problem with the switch/routers ARP cache.

I asked my colleagues to do a wireshark capture (port mirroring)

- packets 12-14: LwIP starts and sends ARP gratuitous and IGMP reports
- a pc (192.168.245.14) pings the LwIP device (192.168.241.226),
we can see the packets arriving on the wire, so the router already knows 
the MAC address of the device.
- another PC (192.168.245.11) is trying to connect to TCP port 12302...
- no answer for 34 seconds
- packets 48-51: the LwIP answers to a TCP SYN (arp request to find a 
gateway MAC and SYN ACK)

What's wrong ?
Did someone else meet the same problem ?

I cannot reproduce in my office (no routeur)... next week I'll be able 
to debug.

--
Stephane Lesage

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