Re: DHCP on SBS
- From: Alan <Alan@xxxxxxxxxxxxxxxxxxxxxxxxx>
- Date: Fri, 10 Nov 2006 09:31:12 -0800
The reason they have the DSL modem on the line is because they have a
Wireless bridge to the main office which is unreliable, so last year I
installed a DSL line at that building and had them connect via a vpn thru
the DSL. I set the the systems in this building with hard coded ip adresses
and no dhcp on the router just so they had the option to run wireless bridge,
or VPN via DSL if either should fail. I put a shortcut on their desktops
which ran a batch file to switch gateways when they needed to switch between
wireless and DSL.
I have been lobbying for them to install fibre around the complex and get
rid off DSL and wireless, but as they are soon to move their main office in
the complex (road widenining will cut their main office in half), they are
not prepared to run fibre till they decide where in the complex the new main
office will be built.
Suffice it to say they have now decided to route all issues thru me first.
On this same site I carried out a swing migration a couple of weeks back.
Wow! "swing" sure does make a migration easy.
"Lanwench [MVP - Exchange]" wrote:
In news:41CB3B6A-FF2C-44F9-88DE-47FFB0F8BF3C@xxxxxxxxxxxxx,.
Alan <Alan@xxxxxxxxxxxxxxxxxxxxxxxxx> typed:
Is there any way you can stop the SBS DHCP server function shutting
down when it detects another dhcp server?
I don't think so - but read on.
I had a call from a client this morning telling me that no-one could
connect to the server. The cause! Bell South replaced a DSL
modem/router in one part of the network with a new one, because the
old one was misbehaving. In typical fashion they did not turn off the
DHCP server function of this router and people started pulling IP
addresses from it which naturally didnt have the SBS server IP
address in the DNS settings.
So even if the DHCP server were stil running on SBS at that point, you'd
have no way to ensure that it was the one that dished out addresses. Whoever
answered the clients first, would do it.
As the users all shut down their
computers each night they pulled a new IP address when starting up
this morning and copped the typical huge delay when connecting to the
server when DNS is wrong.
I was lucky to discover the cause and only realised what was going on
when I did an IP config on one of the systems and discovered a
strange gateway and dns address.
I then asked the question, has anyone installed some new network
hardware recently? and then got told that Bell-South had been in
yesterday.
So I got onto Bell-South (and that can be a real achievemnet
sometimes) obtained the router Password and turned of DHCP.
As the SBS server is on a faster link than the part of the complex
where the new router was installed I feel confident that had the DHCP
service on the server not shut down, they would have pulled the
correct addresses without IP adr conflict (the server uses 50-99 as
its range and the bell-souther router used 101 onwards)
But it would have been nice if SBS had not shut down its DHCP server
service.
You can't functionally work with two DHCP servers on the LAN - unless
they're configured properly with non-overlapping scopes.
The right solution to the problem above is: your clients should be notifying
*you* before any vendor comes in and replaces any kind of network equipment.
I'll bet they've learned that lesson now, right?
I'm not sure why you have this additional modem on your LAN anyway - what's
it for, and why is it connected directly to your LAN rather than to either a
separate hardware appliance (router) or the 2nd NIC of a properly-configured
computer/server ?
Alan
(in Australia, its already tomorrow)
- References:
- Re: DHCP on SBS
- From: Lanwench [MVP - Exchange]
- Re: DHCP on SBS
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