Tut Systems SMS2000 manual Static Routable Addresses, Dhcp Pools

IP Addressing

Figure 11-1 Plug and Play with NAT

Client A believes that it’s IP address is 38.1.43.32 and client B believes it’s IP address is 141.211.43.87. The SMS2000 will respond to each of these clients as their respective gateways, 38.1.43.1 and 141.211.43.1. By using Network Address Translation (NAT), each of these clients is actually sharing the SMS2000’s network-side address of 217.44.23.76.

This capability is called “plug and play” since the SMS2000 is automatically adjusting to the client.

In the simplest configuration without RADIUS or the OCS, if a client attempts to learn its address with DHCP, the SMS2000 can respond with an arbitrary IP address. This address can be remembered and may not be given to other clients to prevent address collisions on the subscriber Ethernet side, if the subscriber media pass broadcasts between clients. The

SMS2000 always responds to client DHCP requests.

The SMS2000 can also respond with an IP address from a configured DHCP pool. If that pool is out of IP addresses, the SMS2000 will revert to using NATed addresses.

Static Routable Addresses

It is not always desirable to treat each host on the subscriber network as a client. For example, an Ethernet switch of an Expresso MDU Lite has an SNMP management agent that must be accessed outside of the subscriber network by a static routable IP address. In this case, the SMS2000 allows an administrator to set up static configurations for given IP addresses. No address translation or authentication is performed on static addresses.

Note: Subscribers can get static IP address via RADIUS, SMS2000 rules, or OCS-based service provisioning.

Note: The Static routable addresses must be in the same subnet as the

SMS2000 or in a control-net.

For example,

sms2000% group add specials sms2000% iptype static

sms2000% set rule ip101 1 ip=192.168.0.101,255.255.255.255

DHCP Pools

With DHCP a subscriber gets the same IP address as often as possible. The DHCP archiving feature archives past IP address assignments to track previous IP address allocations between reboots of the SMS2000.

The SMS2000 allows the network provider to specify multiple-named DHCP pools that must correspond to real addresses (i.e., not NATed). The SMS2000 then applies policies to determine which clients get addresses from which pools. The OCS can load the policy information such that, for example, a subscriber paying a lower rate gets an arbitrary address that goes through NAT while a subscriber paying a higher rate gets an address

TUT Systems, Inc Page 70 of 104 P/N 220-06288-20