Defining a Pool of IP Interfaces for Dynamic IP Address Allocation

To configure a server to support dynamic IP address allocation, you must define a pool of point-to-point IP interfaces that will be assigned to the clients as required. These interfaces are always marked down by default.

For example, to create a pool of n point-to-point IP interfaces for dynamic IP address allocation:

ifconfig ipdptp0 plumb
ifconfig ipdptp0 local rem1 netmask 255.255.255.0 mtu 1500 down
 
ifconfig ipdptp1 plumb
ifconfig ipdptp1 local rem2 netmask 255.255.255.0 mtu 1500 down
 
ifconfig ipdptp2 plumb
ifconfig ipdptp2 local rem3 netmask 255.255.255.0 mtu 1500 down
.
.
ifconfig ipdptpn plumb
ifconfig ipdptpn local remn netmask 255.255.255.0 mtu 1500 down

The number of interfaces in the pool should equal the number of asynchronous devices (modems) attached to the server, and the maximum number of interfaces in the pool is 512. The total number of clients supported by the server may be much greater.

If you have a small number of clients, or the same number of clients and modems, you can assign the interfaces statically. In this case, when a client requests an IP address, it is always assigned the same one from the pool.

If you have a large number of clients, or many more clients than modems, you can assign the interfaces dynamically. In this case, when a client requests an IP address, it is assigned one from the pool, but there is no guarantee that it will always receive the same one.

See "Defining Asynchronous Paths (dialup_path)" for instructions on how to assign static and dynamic IP interfaces.