Force IP renewal across network

Hi,

Is there a way to tell all DHPC clients on your network to update their
TCP/IP configuration. I want to change the IP address range of my pretty
small LAN from the public range it is currently using (not sure why it was
set up like that) to a RFC compliant private range.

Or, if you make a change on the DHCP server does it automatically tell
clients to update?

TIA,

Jarryd

The best way is to reduce the lease period at any time when you are making
changes to the network, then push it back up again later. As someone said
recently, DHCP is passive. It answers requests for addresses when asked.
Then the PC's go away and don't come back to moma till the lease expires and
they want another one.
If you can't wait then you have to run ipconfig /release on each machine.
Anthony



"Jarryd" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi,
>
> Is there a way to tell all DHPC clients on your network to update their
> TCP/IP configuration. I want to change the IP address range of my pretty
> small LAN from the public range it is currently using (not sure why it was
> set up like that) to a RFC compliant private range.
>
> Or, if you make a change on the DHCP server does it automatically tell
> clients to update?
>
> TIA,
>
> Jarryd
>

In news:(E-Mail Removed),
Anthony <(E-Mail Removed)> stated, which I commented on below:
> The best way is to reduce the lease period at any time when you are
> making changes to the network, then push it back up again later. As
> someone said recently, DHCP is passive. It answers requests for
> addresses when asked. Then the PC's go away and don't come back to
> moma till the lease expires and they want another one.
> If you can't wait then you have to run ipconfig /release on each
> machine. Anthony

Well, actually they will come back to 'momma' at 50% of the lease period to
refresh the lease.

As for the PCs, you will be surprised that XP will auto acquire it. But for
practical purposes, you can send an email out to everyone prior to the
change to shutdown their workstations so upon restart the next day, they
will get the new lease. Or create a script using PSExec that will go out and
run an ipconfig /release and then a /renew.

--
Ace
Innovative IT Concepts, Inc
Willow Grove, PA

This posting is provided "AS-IS" with no warranties or guarantees and
confers no rights.

Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSE+I, MCT, MVP
Microsoft MVP - Directory Services
Microsoft Certified Trainer

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The only constant in life is change...

Hi Anthony,

As the clients checks to see if it can still use their leased IP address
each time they start up I imagine that for most desktops (which should be
turned off when people leave) will get new addresses. That leaves the
machines that are left on permanently, but there aren't many of those and
the reduced lease time should sort that out, or I could just restart them.
What I am not sure of is if the just lease a new IP address / mask, or does
it renew the entire TCP/IP config? When I change the scope to something
totally different I will also change the DNS, router, WINS, etc. settings
and wanted to know that they would be updated as part of the start-up
discovery process.

TIA,

Jarryd

"Anthony" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> The best way is to reduce the lease period at any time when you are making
> changes to the network, then push it back up again later. As someone said
> recently, DHCP is passive. It answers requests for addresses when asked.
> Then the PC's go away and don't come back to moma till the lease expires
> and they want another one.
> If you can't wait then you have to run ipconfig /release on each machine.
> Anthony
>
>
>
> "Jarryd" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> Hi,
>>
>> Is there a way to tell all DHPC clients on your network to update their
>> TCP/IP configuration. I want to change the IP address range of my pretty
>> small LAN from the public range it is currently using (not sure why it
>> was set up like that) to a RFC compliant private range.
>>
>> Or, if you make a change on the DHCP server does it automatically tell
>> clients to update?
>>
>> TIA,
>>
>> Jarryd
>>
>
>

"Jarryd" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Or, if you make a change on the DHCP server does it automatically tell
> clients to update?

No it doesn't. DHCP is passive. Think of DHCP as a basket of numbers that
everyone grabs one from,...the basket just sits there and make the numbers
available,...it doesn't jump up and take your number away and give another
one.

You can set a very short lease period, but it won't take effect until the
current lease expires and the client "renews". It is the client that is in
control of when the lease expires, the DHCP simple told it the date/time of
the expiration during the last renewal. When the client sees it's lease is
nearing the date, it runs home to mamma (the DHCP) and renews. If the lease
is completely expired and the DHCP is down, the Client can't renew and
starts to appear on milk cartons.

Changing the LAN's IP Range is not a simple task. Short of using
nightmare-ish Multi-netting or running new and old subnets together with
routers between,... it is pretty much impossible to do gradually. It pretty
much has to be done all in one shot,...and then you have to accomidate the
Internet connectivity involving the proxying or nat'ing of the new RFC
addresses which would not have been done prior,..so there is a Topology
change to go along with it.


--
Phillip Windell [MCP, MVP, CCNA]
www.wandtv.com
-----------------------------------------------------

1) There is a Microsoft option to release on Shutdown. You don't want this
except in particular cases. And anyway they would have to obtain a new lease
to get this setting.
2) Yes, they will get the whole package of settings in the DHCP Scope
Options,
Anthony



"Jarryd" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> Hi Anthony,
>
> As the clients checks to see if it can still use their leased IP address
> each time they start up I imagine that for most desktops (which should be
> turned off when people leave) will get new addresses. That leaves the
> machines that are left on permanently, but there aren't many of those and
> the reduced lease time should sort that out, or I could just restart them.
> What I am not sure of is if the just lease a new IP address / mask, or
> does it renew the entire TCP/IP config? When I change the scope to
> something totally different I will also change the DNS, router, WINS, etc.
> settings and wanted to know that they would be updated as part of the
> start-up discovery process.
>
> TIA,
>
> Jarryd
>
> "Anthony" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> The best way is to reduce the lease period at any time when you are
>> making changes to the network, then push it back up again later. As
>> someone said recently, DHCP is passive. It answers requests for addresses
>> when asked. Then the PC's go away and don't come back to moma till the
>> lease expires and they want another one.
>> If you can't wait then you have to run ipconfig /release on each machine.
>> Anthony
>>
>>
>>
>> "Jarryd" <(E-Mail Removed)> wrote in message
>> news:(E-Mail Removed)...
>>> Hi,
>>>
>>> Is there a way to tell all DHPC clients on your network to update their
>>> TCP/IP configuration. I want to change the IP address range of my
>>> pretty small LAN from the public range it is currently using (not sure
>>> why it was set up like that) to a RFC compliant private range.
>>>
>>> Or, if you make a change on the DHCP server does it automatically tell
>>> clients to update?
>>>
>>> TIA,
>>>
>>> Jarryd
>>>
>>
>>
>
>