Digital network modem with an integrated DHCP server
View Patent ↗The digital network modem has a built-in Dynamic Host Configuration Protocol (DHCP) mechanism for dynamically assigning network addresses to clients on the local network. To prevent confusion with a potentially existing DHCP server on the local network, an autosense mechanism is provided to detect the existence of a DHCP server and disable the internal, built-in DHCP mechanism. At power-on, the modem has no knowledge of clients on the local network, and the addresses in use are checked prior to operation. Addresses in use are placed in a list in a store of unknown addresses, and are not assigned to clients requesting DHCP addresses. When a DHCP client requests an address and has as its current address one of the addresses on the list, the current address is removed from the list. The list of unusable addresses is thus minimized and the same address will not be used for two clients.
1. A network modem device, comprising:
an integrated mechanism operative as a first dynamic address assignment server for dynamically assigning network addresses on a network;
a controller circuit operative to detect a presence of a second dynamic address assignment server on the network;
an interrupter operative to send a disable signal to the integrated mechanism for disabling the integrated mechanism in response to the detection of the presence of the second dynamic address assignment server on the network by the controller circuit, the interrupter being further operative otherwise to allow the integrated mechanism to dynamically assign network addresses on the network; and
a memory store for storing unknown used addresses,
wherein the integrated mechanism comprises a start-up mechanism for checking availability of addresses on the network and for placing used addresses in the memory store of unknown used addresses, and an address manager for selecting new addresses not included in the store of unknown used addresses and for removing addresses from the store of unknown used addresses when a client having one of the addresses in the store of unknown used addresses requests a dynamically assigned address.
2. The device according to claim 1 , wherein said device is a digital network modem.
3. The device according to claim 2 , wherein said device is an ISDN modem.
4. The device according to one of claims 1 to 3 , wherein said integrated mechanism provides a DHCP server function.
5. The device according to claim 4 , wherein said controller circuit broadcasts a DHCP discover message on the network and listens to a response to detect said presence of said server.
6. A method of operating a network modem device, comprising the steps of:
providing a network modem device including an integrated mechanism operable as a first dynamic address assignment server for dynamically assigning network addresses on a network;
detecting a presence of a second dynamic address assignment server on the network;
sending, to the integrated mechanism, a disable signal to disable the integrated mechanism in response to the detection of the presence of the second dynamic address assignment server on the network, and otherwise allowing the integrated mechanism to dynamically assign network addresses on the network;
checking availability of addresses on the network after power on and loss of memory of previously dynamically assigned addresses;
storing used addresses in a store of unknown used addresses;
selecting new addresses not stored in response to a request for a dynamically assigned address; and
removing an address from the store of unknown used addresses when a client having one of the addresses in the store of unknown used addresses requests a dynamically assigned address.
7. The method according to claim 6 , wherein said device is a digital network modem.
8. The method according to claim 7 , wherein said device is an ISDN modem.
9. The method according to one of claims 6 to 8 , wherein said integrated mechanism provides a DHCP server function.
10. The method according to claim 9 , wherein said detecting comprises broadcasting from said device onto said network a DHCP discover message and listening to a response to detect said presence of said server.