[WinMac] Re: fixed IP numbers in a DHCP range

Bryan Keet(bryan.keet[at]vicomsoft.com)
Mon, 1 Feb 1999 10:34:57 +0000

Any half-decent DHCP server should offer facilities to allow you to easily assign static addresses to specified machines, based on MAC (ethernet) addresses.

It's common practice to configure TCP/IP network resources to use DHCP (Or its older equivalent BootP) but have them assigned a fixed address from the DHCP server. This provides a easy central adminstration point for all addresses on the network.

eg. If you have ten servers you want to change addresses, you can just change the DHCP server prefs relating to them, rather than change every server. The DHCP lease will expire on the servers, then they will be re-allocated the new addresses.. easy, painless.

If course, certain DHCP servers are not renowned for their ease-of use...

Regards,

Bryan Keet
Vicomsoft
mailto:bryan.keet@vicomsoft.com
http://www.vicomsoft.com

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Vicomsoft - Specialising in TCP/IP solutions for Windows & MacOS

> Hello!
>
> The reason I recommended not "nailing" an IP address in a DHCP environment
>is that some of the readers of this list don't know how to reserve an IP
>address... After all, NT's DHCP server isn't too hot in this respect.
>
> Michael is lucky because he has access to people who know how to set up
>DHCP properly -- In his case, with Linux.
>
> Cheers!
> Dan
>
>At 11:21 PM 1/29/99 +0800, Michael Eilon wrote:
>>At 8:32 PM -0500 28/1/99, Alex Dearden wrote:
>>>> It's bad practice to "nail" an IP address in a DHCP environment,
>>>>because
>>>>if you take the device offline and the address lease expires, and then you
>>>>bring the device back online you'll have two devices with the same IP
>>>>address... And all hell breaks loose.
>>>
>>>So, increase the time of the lease. If NT needs an IP address and there
>>>is a reserved address but the device is offline. It'll use that address.
>>
>>Forgive me if I'm being dense, but why not simply have the DHCP server
>>reserve IP numbers based on the ethernet address of the device?
>>
>>Not that I'm an expert on DHCP, but my colleague who's in charge of the
>>Departmental Server (Debian Linux) has DHCP set up in this way: we have a
>>number of printers (and really old Macs) that can't handle DHCP, so I get
>>him the ethernet addresses, and he allocates a fixed IP number for them.
>>
>>Haven't had any problems with this setup, even if there's downtime for the
>>those devices... as far as I can make out, the DHCP server doesn't allocate
>>the "reserved" IP number until the device with the appropriate ethernet
>>number comes back online.
>>
>>Maybe I'm missing something, and there are reasons why our setup is not
>>good in certain situations, but it seems like a painless way to have static
>>IP numbers in a DHCP environment.
>>
>>Cheers,
>>
>>Michael Eilon
>>Assistant computer manager
>>Dept. of Physics
>>University of Western Australia
>
>
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This archive was generated by hypermail 2.0b2 on Mon Feb 01 1999 - 02:37:24 PST