RE: [lwip-users] Variation in start-up IP address

[Bill Auerbach]

I agree it would be nice to come up the same every time, but the RFC doesn’t require that it do this.  It does recommend that it does.  Is there a reason you want it to be static?  You can undefine LWIP_AUTOIP_CREATE_SEED_ADDR and the IP address will be set to 169.254.mac[4].mac[5] where mac[4/5] are the last 2 bytes of your MAC address.

 

Bill

 

From: address@hidden [mailto:address@hidden On Behalf Of Alex Brophy
Sent: Thursday, April 08, 2010 10:49 AM
To: address@hidden
Subject: [lwip-users] Variation in start-up IP address

 

My application enables DHCP and auto-IP in lwipopts.h. My test environment consists of a standalone board connected via ethernet cable to a spare ethernet port on a PC. There is no DHCP server involved, so I would expect the IP address to always come up as 169.254.254.169. Most of the time it does, but occasionally, it comes up as 169.254.254.170 or more rarely 169.254.254.171. Why does this happen? Is there a way to make the IP address deterministic when DHCP is not available?

 

Alex Brophy