Mapping a MAC to an IP...

Luis Fernando Lacayo lflacayo at
Wed Jan 21 16:36:22 UTC 2009


have you considered creating a new subnet for servers that are not
Production ready?  

During our deployment face, we have what we call a management network,
we use it for during the deployment face and also for the DELL OM / ITA.
When the server is ready for production, we activate the other nic to
the production network.  

You can make your second network as large as you want so you will not
run out of IP's and if you make your lease time long enough you should
not have a problem. 

good luck. 

On Wed, 2009-01-21 at 11:17 -0500, Todd Snyder wrote:

> The spot we ran in to this problem the most is on a provisioning network
> - there can be 1 or 200 servers being provisioned, and we found it
> simplest at times to just make host declarations, but we want the range
> for any NEW servers that come in.  Because it's during provisioning
> stuff, we don't want the IP to change, so we ended up assigning the
> first IP they were given by DHCP as their static IP.  not a great
> system, but not something we wanted to fight with, and it just kept
> growing and growing and growing, as hack jobs tend to do :)
> I will have to give the reservation a shot - thanks!!
> Todd.
> -----Original Message-----
> From: dhcp-users-bounces at
> [mailto:dhcp-users-bounces at] On Behalf Of Simon Hobson
> Sent: Wednesday, January 21, 2009 11:00 AM
> To: Users of ISC DHCP
> Subject: RE: Mapping a MAC to an IP...
> At 10:51 -0500 21/1/09, Todd Snyder wrote:
> >My understanding is that you have to "break" the range to add host 
> >declarations.
> >
> >This, to me, is the biggest pain I have with DHCP in a a production 
> >environment.  What could be a nice general range declaration, with some
> >hosts entries turns into a bunch of broken up and hard to dissect range
> >declarations with hosts declarations sprinkled throughout.  for 5 
> >entries, it's no biggie, but when putting in 50 or 60 hosts into a /24 
> >there are a lot of lines. Multiply that by a few /24's and maintenance 
> >gets to be quite difficult at times.
> I've never had a problem that way, but then I'm managed my IP's rather
> than scattering stuff all over the subnet in a random manner ! 
> I guess that's no help if you've inherited a network from an admin that
> just plugged stuff in and let it keep the address it got :-(
> Also, if you are in that situation, there is now (I believe) another
> option - you can mark a lease as reserved and it will be handled the
> same as a dynamic address EXCEPT that it will be kept for use by the
> same client and never re-allocated.
> --
> Simon Hobson
> Visit for books by acclaimed
> author Gladys Hobson. Novels - poetry - short stories - ideal as
> Christmas stocking fillers. Some available as e-books.
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Luis Fernando Lacayo
Chicago Public Schools
Senior Unix Administrator
ITS/ UNIX Infrastructure
Office: 773-553-3835
Cell: 773-203-4493
lflacayo at
               "In God we trust, the rest we monitor ..."

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