User`s manual

Alcorn McBride Digital Video Machine DVM-7400 User’s
Manual Rev 1.5
84
Addresses and Routing
IP Addressing
If we think about the network connections, it is necessary to understand how the
devices connected know where they are and how they find each other. The
method most commonly used for Ethernet networks is the Internet Protocol (IP).
IP uses addresses assigned to devices in the same way your home address is
used by postmen to know what mail is to go to your house. In the Ethernet
network, the IP address is divided into groups like a home address is divided up
for easy reading.
For example, your name, house number, street, city, state and zip code are all
needed to get a letter delivered to your house. The IP address is also divided into
groups but in number form. IP addresses are in four groups of three numbers
separated by periods (dots). The default IP address for many IP based products
is 192.168.0.254 (192 dot 168 dot 0 dot 254), where each number can be in the
range of 0-254. Every port on the network must have a unique IP address just as
in the address for your mail. If we think of the IP address as a mailing address for
your home, the first number could be the state = 192, the second could be the
city = 168, the street = 0 and the house number = 254. We all know how much
computers love numbers so we have number addresses for network
identification.
Subnet Mask
In order make the connections as fast as possible, there is a parameter that
filters the network and is called the Subnet Mask. The subnet mask parameter is
another set of numbers such as 255.255.255.0. In the simplest terms, this
parameter will limit the network by allowing the IP addresses to be connected that
have the same fields as those in the subnet mask having the 255. So the IP
address, in our case 192.168.0.254 (port A), will be able to communicate with all
other devices that have 192.168.0.(0-255) as their IP address. If the subnet
mask is 255.255.0.0, the device could communicate with other devices in the
range 192.168.(0-255).(0-255). IP addresses that end in 0 are special, as are
any value of 255; these are not used for simple networking. The smaller the
subnet mask-number the larger the subnet will be. You may never need to
change this parameter unless you need to communicate with more than 254
devices.
Gateway
The Gateway parameter is another way to isolate very large networks. The
gateway address is the IP address of a router or similar device that is connected
to more than one network. It allows a computer on one network to ask for the
address of a device on another network.
Connecting the Hardware
We can now configure the machines on our network as shown in the diagram that
was introduced at the start of this section. Let’s first build the simplest network,
the point-to-point network. The point-to-point network will have a PC connected to
a device such as a DVM7400/E, AM4/E or V16Pro or any other IP based device.
Again, this is like using the RS232 port to talk to a device connected to the PC
with a serial cable. Each device must have an IP address assigned. Pick an
address that you will remember for the PC’s IP address. It is best to keep the IP
addresses of your devices separate from those of the equipment that is making
up network. For example, put network devices like routers, servers and gateways
that need an IP address down low in the address range (i.e 192.168.1.1 through
192.168.1.99) and devices to control such as the PC, in the high address (i.e