Re: [lwip-users] Changing MAC address of network interface?

[Sergio R. Caprile]

Hi,
as long as you are not using an application protocol that embeds layer-2 
info in application data, you shouldn't have any issues with buffered 
data in lwIP, since it does not hold layer-2 info; it is added by the 
driver. You would need to restart your DHCP or AutoIP, and your PPPoE. 
SNMP is UDP and so not buffered, so that is it for included apps and 
IPv4. IPv6 might also need some restart of the node discovery process as 
neighbours would have old (and wrong) information.
If I am missing something, please let me know.
As per established data flows, other hosts will send to the old MAC 
until their respective ARP cache entries expire, and that depends on 
their respective timeouts. I've seen upto 4 minutes as normal.
And yes, this not something you are expected to do on a normal 
operation, so resetting is the best choice.