HOW TO DO DYNAMIC ALLOCATION:

DHCP server: 			128.2.7.5
DHCP server's subnet mask:	255.255.255.0
Relay Agent 1:			128.2.5.254
Relay Agent 1's subnet mask:	255.255.255.0
Relay Agent 2:			128.2.8.1
Relay Agent 2's subnet mask:	255.255.255.128
Relay Agent 3:			128.2.8.254
Relay Agent 3's subnet mask:	255.255.255.128


I have set aside the following ip addresses for dynamic allocation:


128.2.7.50
128.2.7.51
128.2.7.52
128.2.7.53
128.2.7.54
128.2.5.63
128.2.5.64
128.2.5.65
128.2.5.66
128.2.8.100
128.2.8.101
128.2.8.102
128.2.8.150
128.2.8.151	


FIRST:
I need to decide upon a configuration for each of these ip addresses. I can't
use the same configuration for all since they have different routers and
netmasks.

subnet7:gw=128.2.7.254:sm=255.255.255.0:dn=128.2.53.50:wn=128.2.53.60:
dynmaic7-1.net.cmu.edu:ip=128.2.7.50:dy:tc=subnet7:
dynmaic7-2.net.cmu.edu:ip=128.2.7.51:dy:tc=subnet7:
dynmaic7-3.net.cmu.edu:ip=128.2.7.52:dy:tc=subnet7:
dynmaic7-4.net.cmu.edu:ip=128.2.7.53:dy:tc=subnet7:
dynmaic7-5.net.cmu.edu:ip=128.2.7.54:dy:tc=subnet7:

subnet5:gw=128.2.5.254:sm=255.255.255.0:dn=128.2.53.50:wn=128.2.53.60:
dynmaic5-1.net.cmu.edu:ip=128.2.5.63:dy:tc=subnet5:
dynmaic5-2.net.cmu.edu:ip=128.2.5.64:dy:tc=subnet5:
dynmaic5-3.net.cmu.edu:ip=128.2.5.65:dy:tc=subnet5:
dynmaic5-4.net.cmu.edu:ip=128.2.5.66:dy:tc=subnet5:

subnet8-lo:gw=128.2.8.1:sm=255.255.255.128:dn=128.2.53.50:wn=128.2.53.60:
dynmaic8-1.net.cmu.edu:ip=128.8.8.100:dy:tc=subnet8-lo:
dynmaic8-2.net.cmu.edu:ip=128.8.8.101:dy:tc=subnet8-lo:
dynmaic8-3.net.cmu.edu:ip=128.8.8.102:dy:tc=subnet8-lo:

subnet8-hi:gw=128.2.8.254:sm=255.255.255.128:dn=128.2.53.50:wn=128.2.53.60:
dynmaic8-4.net.cmu.edu:ip=128.2.8.150:dy:tc=subnet8-hi:
dynmaic8-5.net.cmu.edu:ip=128.2.8.151:dy:tc=subnet8-hi:

Note:
a)the "dy" flag is important. It siginifies that this particular ip is intended
  for dynamic allocation. This is so ip's belonging to static entries are not 
  served out. 
  e.g.
   mymachine.net.cmu.edu:ha=00000C723456:ht=ethernet:ip=128.2.7.42:tc=subnet7:
  does not get dynamically allocated.
b)relay agent address is the same as the router's address. This is just a
  coincidence, not a requirement.
  

SECOND:
now let's group these ip addresses and set permissions.
You do this in the dhcpd.conf file.

# network <name> <network-number> <network mask> <access>
# access := both | romaing | <type>
# type := dhcp | bootp | both
# Most of the time you just want "both"
network subnet-7 128.2.7.0 255.255.255.0 both
network subnet-5 128.2.5.0 255.255.255.0 both
network subnet-8-lo 128.2.8.0 255.255.255.128 both
network subnet-8-hi 128.2.8.255 255.255.255.128 both

#gateway <relay agent's ip address> <relay agent's subnet mask> [<network-name>
#	<network-name> <network-name> .....]
gateway 128.2.7.254 255.255.255.0 subnet-7
gateway 128.2.5.254 255.255.255.0 subnet-5
gateway 128.2.8.1 255.255.255.128 subnet-8-lo
gateway 128.2.8.254 255.255.255.128 subnet-8-hi


That's it. It should start dynamically allocating ip addresses with just this.
You can always strip this down to whatever you need.

5/2/96 chr@andrew.cmu.edu