Re: [lwip-devel] why the board sends Gratuitous ARP always?

[Mason]

fangcheng_gmail wrote:

> I'm try to implement LWIP on a board based on the MCU MPC5604E from
> Freescale.
> 
> I set the IPv4 address to 169.254.1.60 manually (not by DHCP or AUTOIP),
> the board direct connects to one PC with IP address 169.254.1.20. (Network
> gateway is 169.254.1.1)
> 
> After each power on reset, the boards always sends gratuitous ARP
> continuously.
> 
> The attached picture shows this condition.
> 
> What's wrong?

$ grep -rn gratuitous src
src/core/ipv4/autoip.c:441:              * autoip_bind calls netif_set_up. This 
triggers a gratuitous ARP
src/core/netif.c:466:      /* For Ethernet network interfaces, we would like to 
send a "gratuitous ARP" */
src/core/netif.c:468:        etharp_gratuitous(netif);
src/core/netif.c:554:      /* For Ethernet network interfaces, we would like to 
send a "gratuitous ARP" */
src/core/netif.c:556:        etharp_gratuitous(netif);
src/include/netif/etharp.h:188:/** For Ethernet network interfaces, we might 
want to send "gratuitous ARP";
src/include/netif/etharp.h:192:#define etharp_gratuitous(netif) 
etharp_request((netif), &(netif)->ip_addr)
src/netif/etharp.c:11: * if an interface calls etharp_gratuitous(our_netif) 
upon address change.

Perhaps try setting a break point in etharp_gratuitous
(an alias for etharp_request by default) and see who is
calling it continuously, and under what conditions.

Maybe the link (or the iface) is going up and down?

-- 
Regards.