Specifications

Getting Started 25

4.2 Running TCP/IP Sample Programs

We have provided a number of sample programs demonstrating various uses of TCP/IP for

networking embedded systems. These programs require that the user connect his PC and

the RCM3000 board together on the same network. This network can be a local private

network (preferred for initial experimentation and debugging), or a connection via the

Internet.

Obtaining IP addresses to interact over an existing, operating, network can involve a num-

ber of complications, and must usually be done with cooperation from your ISP and/or

network systems administrator. For this reason, it is suggested that the user begin instead

by using a direct connection between a PC and the RCM3000 board using an Ethernet

crossover cable or a simple arrangement with a hub. (A crossover cable should not be con-

fused with regular straight through cables.)

In order to set up this direct connection, the user will have to use a virgin PC (right out of

the box), or disconnect a PC from the corporate network, or install a second Ethernet

adapter and set up a separate private network attached to the second Ethernet adapter. Dis-

connecting your PC from the corporate network may be easy or nearly impossible,

depending on how it is set up. If your PC boots from the network or is dependent on the

network for some or all of its disks, then it probably should not be disconnected. If a sec-

ond Ethernet adapter is used, be aware that Windows TCP/IP will send messages to one

adapter or the other, depending on the IP address and the binding order in Microsoft prod-

ucts. Thus you should have different ranges of IP addresses on your private network from

those used on the corporate network. If both networks service the same IP address, then

Windows may send a packet intended for your private network to the corporate network.

A similar situation will take place if you use a dial-up line to send a packet to the Internet.

Windows may try to send it via the local Ethernet network if it is also valid for that net-

work.

The following IP addresses are set aside for local networks and are not allowed on the

Internet: 10.0.0.0 to 10.255.255.255, 172.16.0.0 to 172.31.255.255, and 192.168.0.0 to

192.168.255.255.

RCM3000

User’s PC

Ethernet

crossover

cable

Direct Connection

(Network of 2 computers)

RCM3000

Hub

Ethernet

cables

To additional

network

elements

Direct Connection Using a Hub

Board