The Avahi daemon, installed by default with SL5.x , is the 
program that configures a 169.254.xxx.xxx address on disconnected
ethernet ports - such as the one on your laptop when you are
away from a hard connection for a while, or the ones on your 
desktops when your router's power goes out.  Avahi is a version
of zeroconf, and related to something called "link local".  It
is allegedly useful for connecting two ethernet ports with a
crossover cable.  However, it is also persistent, and when a
DHCP server becomes available, ready to assign a proper address,
the previously assigned (and useless) 169.254.xxx.xxx address
persists.  Avahi also sends out frequent discovery packets, 
adding noise to tcpdump debugging sessions.

This is a bug, not a feature.  I disabled it on my laptop with
System -> Administration -> Server Settings -> Services , but
I'm wondering if there is something needful that breaks when
I disable Avahi .   

Otherwise, I will turn it off on all my machines.

Keith

-- 
Keith Lofstrom          [log in to unmask]         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs