Wavetronix Click 342 (lean managed ethernet switch) (CLK-342) - Managed Switches User Guide - Manual (Page 17)

16 CHAPTER 1 • CLICK 340/341/342 MANAGED SWITCHES
IP addresses can be represented in decimal or hexadecimal form. In decimal notation, bytes
are separated by dots (dotted decimal notation) to show the logical grouping of the indi-
vidual bytes.
Example
The decimal points do not divide the address into a network and user address. Only
the value of the first bits (before the first zero) specifies the network class and the
number of remaining bits in the address
The figure below shows the possible address combinations (see Figure 2.2).
Figure 2.2 – Structure of IP addresses
Certain IP addresses are reserved for special functions. The following addresses should not
be used as standard IP addresses:
˽ 127.x.x.x Addresses – The Class A network address “127” is reserved for a loopback
function on all computers, regardless of the network class. This loopback function may
only be used on networked computers for internal test purposes.
If a telegram is addressed to a computer with the value 127 in the first byte, the receiver
immediately sends the telegram back to the transmitter.
The correct installation and configuration of the TCP/IP software, for example, can be
checked in this way.
As Layers 1 and 2 of the ISO/OSI reference model are not included in the test they
should be tested separately using the ping function.