Multiple DHCP Servers

Multiple DHCP Servers

Post by Keith Bail » Sun, 12 Sep 2004 01:52:42


I am running NW6 SP5 on mulitple servers.

I want to set up additional DHCP servers as standbys should the main one
fail.

I have set up the DHCP server, the subnet & the address range to be
different from the primary servers. I use the RFC1918 172.16.x.x. class
B range. I have a DHCP server issuing addresses in the 172.16.1.0 subnet
& I have set up another server to dispense addresses in the 172.16.4.0
subnet. The server base IP address is not in this range.

The server starts up fine but won't allocate any addresses. Running
DHCPSRVR with the -d3 switch shows that it says "received packet from
172.16.0.0 subnet. Server is not configured to allocate addresses in
this range".

I saw in an old(ish) TID that the server base IP address had to be
within the DHCP address range. Is this still true & is this why it's
refusing to allocate addresses?
Keith Bailey
Computer Manager
Kingsbury High School
LONDON UK
 
 
 

Multiple DHCP Servers

Post by Erik Klaus » Sun, 12 Sep 2004 03:37:41

Keith Bailey < XXXX@XXXXX.COM > wrote in



What subnet mask do you use?
If you use the class B subnet mask (255.255.0.0), it should work. If you
use 255.255.255.0, you must be having a router between the 172.16.1.0 net
and the 172.16.4.0 net. This router can most likely be configured to
forward DHCP requests to the DHCP server.

Remember the difference between subnets and subnet address ranges. You have
a subnet, and within this subnet you have an address range. For example,
you can reserve addresses 172.16.1.0-172.16.1.10 for routers, servers etc.,
and let the DCHP server hand out addresses 172.16.1.11-172.16.1.254 to
clients.

For redundance, you have two choices:
1. Have one server running, and another server configured, ready for a
manual switch.

2. Configure and run two DHCP servers. This is OK, as long as they don't
hand out from the same address range.

HTH,
Erik Klausen

 
 
 

Multiple DHCP Servers

Post by Alex Tof » Sun, 12 Sep 2004 23:01:47


Sounds like a job for Cluster Services (if you use it). Just add
the dhcpsrvr as a cluster resource and forget about it.

Cheers

Alex
Netware Geek
Leeds Met University
 
 
 

Multiple DHCP Servers

Post by Keith Bail » Mon, 13 Sep 2004 19:22:35

Erik,

Thanks for the reply. I use 255.255.248 as the subnet mask & I am using,
in effect, a class C address range (254 addreses). The range is within
the server subnet mask but the server's IP address is outside the range
that I want the DHCP server to dispense.


In article < XXXX@XXXXX.COM >, Erik Klausen
< XXXX@XXXXX.COM > writes


Keith Bailey
Computer Manager
Kingsbury High School
LONDON UK
 
 
 

Multiple DHCP Servers

Post by Erik Klaus » Tue, 14 Sep 2004 02:01:22

Keith Bailey < XXXX@XXXXX.COM > wrote in



It shouldn't be a problem. I use a 255.255.128.0-subnet mask, my DHCP-
server's address is in the 10.16.32.0-range, and it hands out addresses in
10.16.110.0-range.

In DHCP, I assume you have created a subnet, and within this subnet you
have a subnet address range? The subnet address range is the pool of
addresses that the server hands out. Also, the DHCP server should be
assigned to the subnet.

If te DHCP environment is configured, check that the MAC address of the
computer being rejected, isn't already in the DHCP database. If it is,
delete it.
This shouldn't be a problem, but then again, this is computer business :-)

Erik Klausen