User guide

March 2005 Designing Your Canopy Network
Through Software Release 6.1
Page 116 of 425 Issue 1
Canopy System User Guide
13 ENGINEERING YOUR IP COMMUNICATIONS
13.1 UNDERSTANDING ADDRESSES
A basic understanding of Internet Protocol (IP) address and subnet mask concepts is
required for engineering your IP networking.
13.1.1 IP Address
The IP address is a 32-bit binary number that has four parts (octets). This set of four
octets has two segments, depending on the class of IP address. The first segment
identifies the network. The second identifies the hosts or devices on the network. The
subnet mask marks a boundary between these two sub-addresses.
13.2 DYNAMIC OR STATIC ADDRESSING
For any computer to communicate with a Canopy module, the computer must be
configured to either
◦ use DHCP (Dynamic Host Configuration Protocol). In this case, when not
connected to the network, the computer derives an IP address on the 169.254
network within two minutes.
◦ have an assigned static IP address (for example, 169.254.1.5) on the 169.254
network.
IMPORTANT!
If an IP address that is set in the module is not the 169.254.x.x network
address, then the network operator must assign the computer a static IP
address in the same subnet.
13.2.1 When a DHCP Server is Not Found
The following is a synopsis of an Internet Draft available at
http://www.ietf.org/internet-drafts/draft-ietf-zeroconf-ipv4-linklocal-05.txt
. This draft
describes how Microsoft and Apple operating systems react when a DHCP server is not
found on the network.
To operate on a network, a computer requires an IP address, a subnet mask, and
possibly a gateway address. Either a DHCP server automatically assigns this
configuration information to a computer on a network or an operator must input these
items.
When a computer is brought online and a DHCP server is not accessible (such as when
the server is down or the computer is not plugged into the network), Microsoft and Apple
operating systems default to an IP address of 169.254.x.x and a subnet mask of
255.255.0.0 (169.254/16, where /16 indicates that the first 16 bits of the address range
are identical among all members of the subnet).