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Ron asks:
> I've been working on converting from the bundled dhcp server
> that comes with HPUX 10.20 to the ISC dhcp server, and have
> a couple of questions:
>
> 1) I found the note in the README that says I need to change
> my broadcast address to all ones (symptoms deleted)
Your symptoms are EXACTLY what will happen if you don't
have an all-ones broadcast.
> Why doesn't the bundled HP dhcp server have this same problem
> in getting offers accepted by the clients?
Because HP knew the 'tricks' of working with their IP stack, and
wrote very specific code to send the 'right thing'. The ISC DHCP
server does not - can not - rely on knowing every nuance of
every version of every OS, thus it relys on the host doing the
'Right Thing' as defined by generally accepted programming
standards - and when the OS doesn't cooperate, we the
SysAdmins have to figure out how to trick it into working.
> IOW, the only piece that changed is the dhcp server software,
> and now the local win clients are unable (or are refusing) to
> accept offers.
Because the packet being sent by the ISC server - or more correctly,
the packet being delivered by the HP stack - is not in the specific
format required by the client. And the problem is that it does not
have an all-ones broadcast.
> 2) The README says that it's the "picky windows" clients that
> are causing the problem, but if they are performing to the
> spec (the RFCs), isn't the problem really somewhere else?
The underlying theory of the Internet is: Be conservative in what
you do and liberal in what you accept. This means that, ideally,
what a program will SEND will EXACTLY meet the specifications
and requirements. What a program will ACCEPT will be anything
that can be intelligently deciphered. Thus, a 'correct' client will
ignore a packet without all-ones. But an INTELLIGENT one will
realize that the packet is valid, just slightly out of spec, and
accept the data.
===
Now, why does a local host not work but a 'relayed' one does?
Because the relay agent doesn't propagate all-ones broadcasts,
but rather properly sets up the relayed packet so the client finds
it acceptable. If you move your DHCP server behind a relay, you
never have to deal with the all-ones issue!
Your solution is to realize that the HP stack is a little stubborn, and
so are the M$ clients. Just set the all-ones hack and trust that it
works. That's why Ted wrote the README. Trust him. Trust his
code.
John F Sandhoff, University Network Support
California State University, Sacramento
[EMAIL PROTECTED]
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