Modem Driver

Introduction

The modem driver, located in the drivers table and automatically started with the rc service, provides a basic way for modems to participate in a IP network. In addition to basic IP filtering, the driver leverages MAC filtering and modem ports as channels for additional filtering. This farther reduces the client side processing of irrelevant packets.

In addition to the standard MAL entries, The modem driver contains the following entries

• hw_type: always "modem"
• hw_addr: the MAC (component) address, this the component that invokes are called against
• hw_channel: the modem's port to use for sending and receiving, load opens this if it's not already open. Note, failure to open this results in the state automatically being set to false
• arp_cache: a table containing recently acquired arp's and the max_entries key, whose value determines when entries will start being cleared

Usage

In addition to standard MAL Driver functions, the following should be noted

create(name,hw_addr,channel,cache,addr,subnet,dhcp)

• name: the name the interface will be referenced by in the interfaces table
• hw_addr: the component address that will be used
• channel: the port that will be used
• cache: the max number of arp entries that should be stored, the higher this is, the less arp requests need to be made at the cost of memory
• addr: the IP address the interface will use. Should be set to 0 if DHCP will be used
• subnet: the Subnet mask the interface will use, 0 if using DHCP
• dhcp: whether the interface will have it's address dynamically allocated at boot time