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Ip Addressing

Posted on 2013-05-15
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Last Modified: 2013-06-17
Hi,
How do I create an additional static address in a LAN with both Static & DHCP? As far as I know we have correctly set up a range of dynamic IP's with a statics IP's at either end - routers and file servers. This has been working perfectly. What we need is to slice off one of the dynamic IP addresses and add it to the statics........we think have followed the proceedure and all does appear good and does hold onto it after re-boot - until the PC is powercycled (as part of the energy saving policy - in the evening). The it drops the lease. We run both eDirectory and active directory.........I wondered if one is not handing off to the other properly.
New to this so might be slow on the uptake.
Thanks
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Question by:gavin_d
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mcsween earned 250 total points
ID: 39168643
Chances are you are running DHCP in Active Directory, if not, disregard my answer.

You need to set a reservation for this system or an exclusion range in DHCP.

At your DHCP Server:
Start, Run, dhcpmgmt.msc
Expand IPv4 and the scope in question

If you want to set a reservation, enter the reservation folder then RC, New Reservation, enter Name, IP to be reserved and MAC Address of system to receive the reservation.  The server remains DHCP in this scenario.

If you want to set an exclusion (I would do this if it is a server), enter the address pool folder, right click, new exclusion range, enter start and stop IP addresses.  The server needs a static IP set in this scenario.
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by:Bing CISM / CISSP
ID: 39168660
> How do I create an additional static address in a LAN with both Static & DHCP?

basically, NO.

if DHCP is enabled on the NIC, it cannot be multihomed as DHCP client can only talk to one particular DHCP server and to be assigned with a single IP at a time, even there are multiple DHCP servers or other DHCP scopes are available on the same network.

for multihomed addresses, use static IPs only.
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by:deroode
ID: 39170632
Do you want one PC to have a static IP address?
In the DHCP/DNS management console you can create a "Manual Ip address asignment". That way, the PC still uses DHCP to obtain an IP address, and the DHCP server will always hand out the same address to the assigned MAC address.
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by:Fred Marshall
Fred Marshall earned 250 total points
ID: 39171938
How do I create an additional static address in a LAN with both Static & DHCP? As far as I know we have correctly set up a range of dynamic IP's with a statics IP's at either end - routers and file servers.

I presume this means something like (in an example subnet):
192.168.1.1 to 192.168.1.8 are static.
192.168.1.9 to 192.168.1.250 are in the DHCP pool.
192.168.1.251 to 192.168.1.254 are static.
Is that right?

What we need is to slice off one of the dynamic IP addresses and add it to the statics.

So, to answer your question, you might do something like this relative to the example:
192.168.1.1 to 192.168.1.8 are static.
192.168.1.9 to 192.168.1.249 are in the DHCP pool - reduced by 1.
192.168.1.250 to 192.168.1.254 are static - increased by 1.

One might note that needing "just one more" static address is a sign of poorly structured address assignments where "spares" are concerned.  It's clear that you have no spare static addresses and won't have any spare static addresses once this change succeeds.
A much better practice would be to have a number of spare static addresses.
You should ask: "Do we really need ALL those dynamic addresses??"  Likely not.

So, you might do something like this relative to the example:
192.168.1.1 to 192.168.1.8 are static.
192.168.1.9 to 192.168.1.230 are in the DHCP pool - reduced by 20.
192.168.1.231 to 192.168.1.254 are static - increased by 20.
Now you would have 32 static addresses with 19 of them being spares.  A much more comfortable situation.

Sometimes the number of dynamic addresses is big because the lease times are too long.
Let's say you have 100 dynamic assignments that are "live" at any one time.
Let's say that 10 dynamically assigned computers "appear" or "disappear" each day.
You now have what? 240 dynamic addresses or so?
So, with leases of 14 days you would likely run close to the limit (100 plus 10 per day is 240 after 14 days).
In that case you would be much better off with leases that would be maybe 2 days.
For that matter, why not 4 to 8 hours?


I don't follow this comment:

until the PC is powercycled (as part of the energy saving policy - in the evening). The it drops the lease. We run both eDirectory and active directory.........I wondered if one is not handing off to the other properly.

What does a PC have to do with this issue?
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Expert Comment

by:pgm554
ID: 39177383
If you are running edir,use the Novell DHCP service as you can have multiple DHCP servers on the network and edir keeps track of the IP addresses.

http://www.novell.com/documentation/oes2/ntwk_dnsdhcp_lx/?page=/documentation/oes2/ntwk_dnsdhcp_lx/data/bbjxptj.html
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Author Comment

by:gavin_d
ID: 39178529
Thanks to all comments. i will be back in work on Monday(GMT) to approach this. Will provide feedback ASAP.
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Author Closing Comment

by:gavin_d
ID: 39252835
Apologies for the delay in feedback. All helped - job done.
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