On some machines, they take a few seconds to negotiate their
link speek (ie 10/100), of course the bootp request is sent
out right after the interface is raised.  This can cause
parts ofthe bootp response to be lost.

The solution that worked in the lab was to perform a retry
without bringing the interface down.  in
/etc/sysconfig/network-scripts/ifup, add a retry after the
firsr bootpc request if the return from the first try is a
failure.