Re: Allocating addresses across routers

[Richard Letts <[e-mail]>]

cpeters2 wrote....
> 
> Hi - I have a little dilemma, but first let me explain where I am at.
> I have configured my AIX4.2 box with a DHCP server (it hands out leases,
> it handles bootp both dynamic and static)  All in all I am pretty pleased
> except for this one little thing.  We have a highly subnetted network
> and I would like to have as FEW DHCP servers as possible which means I
> need to forward client requests across the routers.  My router people
> cringe when I tell them this, they are worried about broadcasts.  Is
> there any other way to do address assignment across a router without
> opening it up to ALL broadcast packets?
> 
get out a wet haddock and slap them around the head.

you do NOT want to open up your routers for all broadcast packets.

you want them to enable the BOOTP-RELAY agent on the router.
on cisco's this is a ip helper address, and is specified on a per-interface
basis. you can have multple addresses, and you can put in either the
individual IP addresses of the DHCP servers, or a directed broadcast (which is
what I do)

eg:
!
interface Ethernet 0
ip helper-address 146.87.9.127
!

on a Proteon/Digital router you do
*ta 6
Config> protocol IP
Config> enable bootp-forwarding
Config> add bootp-server <ip address>
Config> ctrl-P
*restart

on a 3com router [YUCK user interface]
you say you want to forward port 67, and add the necessary relay agents for
this port.

on a Novell MPR/fileserver you obtain the bootpfd.nlm and load it with the
right parameters [depends upon the version what the command-line switches are]

before anyone asks, YES, I do have all of the above acting as routers on the
campus network, yes they are all forwarding bootp packets. yes, the replies
are all working. we service 2900+ nodes from a home-writtten[1] bootp server.
hopefully I'll find a DHCP server I can borrow the code from RSN
If you want to see pictures of the campus network(s) check out
http://www.salford.ac.uk/ais/Network/drawings (I'm about to add some more)

This is all of 5 minutes work per router

Richard Letts  
[1] unlike 'homemade brownies' this is really written at home. :-)
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