The Army Research Lab (ARL) wants Internet service capabilities in a product that would be able to transfer data from a remote network site to a host computer. The product will be able to connect a personal computer on a host site to a Local Area Network (LAN) with the help of a microcontroller. The LAN is a remote site that can be set up in different locations to collect data for research and experiments.
The proposed plan for completing this project was to set up a host pc connected to a modem, which in turn will be connected to another modem using phone lines. The second modem will be connected to a microcontroller, which will in turn be connected to a hub. This hub connects the Local Area Network together. The files are transferred using different protocols. The protocols are Point to Point Protocol (PPP) and Transmission Control Protocol/Internet Protocol (TCP/IP).
The method for accomplishing this task is as follows. At the client side the individual computers and microcontrollers of the LAN will be connected to a hub. A hub will be connected to a Rabbit 3000 microcontroller that will route Transmission Control Protocol/ Internet Protocol (TCP/IP) packets from the Ethernet to the serial port connected to the modem. These protocols allow computers to communicate with one another over a LAN or the Internet. The IP of both the Host PC and the Data Origin (Client side) Site are both unique of each other. There are three Classes of IP numbers. The Class of the Data Origin Site is Class C. Class C supports 254 hosts on each of 2 million networks. The IP address of an Internet node on a computer is the numeric address associated with the network interface in the computer. The IP address is a four-byte (with values 0-225) number separated by decimals. The first two sections indicate the location, the third indicate the local subnet, and the last indicate the specific computer. The IP addresses of the network would be provided by the ARL.
The host will then use Dynamic Host Configuration Protocol (DHCP) to establish a link to the remote network. The purpose of DHCP is to enable individual computers on an IP network to extract their configurations from a server or servers, in particular, servers that have no exact information about the individual computers until they request the information. In this case, the microcontroller would act as the server. The microcontroller that best suites this job is the Rabbit 3000 (RCM3000) controller. The RCM3000 was programmed using the Dynamic C. This microcontroller was be provided by the ARL. The microcontroller was programmed to provide the IP number of the LAN through DHCP for the host computer to connect to the LAN. The RCM3000 has both the Ethernet port and the serial port. Both ports were assigned IP addresses. The host computer was able to access the remote network location by dialing out using Point-to-Point Protocol (PPP). For PPP to succeed, both IP addresses of the host and the Network are embedded into the microcontroller. This connection is across the phone lines, using the two 56K modems. To be able to access the information on the LAN, the dialer needed to authenticate themselves by the user name and a password, which is authenticated at the microcontroller. Once the password and username have been authenticated, access is given to the dialer from the Host PC. The controller will also be able to detect a loss of connection and then return to answer mode. The microcontroller would be powered by a 3.3VDC power supply. Access to the network was limited because username and password authentication was necessary to access the network.
Specifications of Project
Due to limitations on
the Rabbit Microcontroller, we had to modify the project a little. We realized
that both ports on the Rabbit Microcontroller could not be open at the same
time. We had to change the scope of the project a little. We sent the
information from the sensor on the network to a buffer on the Ethernet port.
Then we turned off the