-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Brian Winter
Sent: Tuesday, October 21, 2003 4:40 PM
To: [EMAIL PROTECTED]
Subject: Re: [smartBridges] Clients can't DHCP

Hi,

Bit of a novice just setting up first clients, but I have spent the weekend
on a similar problem.  I am confused that you have another APT facing the
APP and working, but perhaps there is something different about the way
clients are connected beyond the APT ?   FWIW heres how I solved mine.

AP and AB behave differently when attempting to get a dhcp lease.  I used AP
'til now successfully with dhcp working well.  When I added my first AB I
eventually discovered that the dhcp server was not behaving as expected.
Its a little complex but you can see whats going on with Ethereal if you
look carefully.  For me it transpired that the dhcp server was responding to
the unicast address - seen by the AB but not by the client on the other
side.  To work correctly the dhcp server must respond to the broadcast
address (Broadcast flag set 0x8000) and the AB will pass this through to the
client to recognise its own mac address in the BootP part of the offer (the
message containing the dhcp lease info).  At first glance with Ethereal it
looks as if the reply is directly to the client address - this will not
work - it won't get past the AB.

The key to this is in the very informative FAQ for the latest AirBridge
software on sB site http://www.smartbridges.com/new/support/faq_ab.php#36
Item 7 entitled How to make sure the client computers behind airBridge can
get IP address automatically from DHCP server with firmware 0.01.04 or
newer?   It has a brief description of how DHCP Discover and Offer packet
work


My dhcp server is (was) part of the "value added" stuff that comes "free"
with Aramiska satellite kit.  I added another firewall with its own proper
dhcp server facing the radio network (Netscreen 5XP - brilliant kit) and
everything is working just fine.

I have also decided to use fixed IP for the infrastructure kit (all sB) as
this is the only sensible option with the way SimpleNMS operates (a really
painful piece of useful software), whilst having all client PCs use dhcp on
a different subnet. Grateful for others ideas / experiences.

Hope this helps.  Even if you don't have ABs it might help someone else !!
bw



Thanks Brian for that nice chunk of information.  I suppose I should list my
configuration:  On campus I have 1 - APPro with 2 - ABIndoor and 2 - ABTotal
associated.  Fiber runs up the hill to feed the APP.  The ABI's have been in
place for almost a year and one of the ABT has been in place for about 2
months.  It's only this latest ABT installation that I'm having trouble
with.  All the SB equipment (infrastructure) has static IP's and all clients
are setup DHCP and everything works, except this latest installation.  All
AB's have the same configuration except for IP and device name.  I even
tried another ABT ( the first was obviously used, with silicone on the
weatherproof connector and previous programming) the second was definitely
brand new.  Same configuration, same result.  BTW I also have another APP
tied into the fiber running in bridge mode providing backhaul 2+ miles:
Fiber - APP - backhaul - APP - APP - 3 ABI's and DHCP works fine for all
clients.  I'll be sniffing some packets today so I'll have some  more detail
to work with.  Thanks again.  Kirk

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