Yaskawa SmartTrac Ethernet Card - Manual (Page 19)

SMART TRAC Ethernet Card
Technical Manual Smart Trac Ethernet Card Configuring the Smart Trac Ethernet Card
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The easiest way to obtain a TCP/IP address for your Smart Trac AC1 host or
computer is to request one from your LAN Administrator. This is especially
true if the device will be on a enterprise-wide LAN.
NOTE: If your internal network is to be used on a self-contained network and
not connecting directly to the public internet or a larger enterprise-wide LAN,
you may use any valid TCP/IP address except for certain reserved addresses
(0.0.0.0, 127.0.0.1, 224.0.0.0 and 255.255.255.255). Most industrial devices fall
into this category.
If on a private network (intranet) you may use any valid Class A, B, or C
address, described below. Most other LANs fall into one of these address classes
and are assigned by the corporation's LAN Administrator.
Any device that connects directly to the internet (not through a "proxy" server)
must be assigned a network ID from the Internet Network Information Center
(InterNIC at www.internic.com). Smart Trac AC1s do not fall into this category.
TCP/IP addresses are grouped into five classes, from Class A through Class E.
The first octet of the IP address specifies its classification.
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Class A – First octet is between 1 and 126 (0 is not allowed, 127 is
reserved as "loopback" address). Organizations with a very large
number of hosts (networked devices) require a Class A address.
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Class B – First octet is between 128 and 191. Large organizations with
as many as 65, 534 networked devices (workstations, printers, routers,
etc) require at least a Class B address.
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Class C – First octet is between 192 and 223. A network with less than
255 networked devices may be assigned a Class C address.
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Class D – First octet is between 224 and 239. These addresses are for
multicast groups, such as RealAudio and Microsoft NetShow.
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Class E – First octet is between 240 and 247. These addresses are
reserved for experimental purposes.
A Subnet Mask defines the split between network and host (device) parts of the
TCP/IP address. It identifies the network octets of the IP address with the
number "255" or "252" and the host octets with the number "0". This defines the
maximum number of different devices (hosts) allowed on the network. A subnet
mask of 255.255.255.0, then, identifies the first three octets of the IP address as
network parts and the last as a single host part. The use of "252" provides one or
bits of additional resolution for hosts.
Example: The address 200.20.16.5 with a subnet mask of 255.255.0.0 identifies
a network with (255*255)-2 hosts, or 65,534 hosts (two is subtracted to allow
for reserved numbers) on the network identified as "200.20".
Fortunately, Microsoft's Windows NT assigns a default subnet mask to an IP
address. It can be changed if necessary. The defaults result in the following
maximum number of networks and hosts allowed per TCP/IP address:
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Class A – 126 networks, 16,777,214 hosts (default subnet
mask=255.0.0.0).
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Class B – 16,384 networks, 65,534 hosts (default subnet
mask=255.255.0.0)
Obtaining TCP/IP
addresses
TCP/IP Address
Classes
TCP/IP Subnet Masks