Technical data

Glossary 8
Agilent Connectivity Guide 211
For example, the full address for 150.215.017.009 is
10010110.11010111.00010001.00001001. The Class B network part
is 10010110.11010111 and the host address is 00010001.00001001.
If this network is divided into 14 subnets, the first four bits of the
host address (0001) are reserved for identifying the subnet.
The subnet mask is the network address plus the bits reserved for
identifying the subnetwork. (By convention, the bits for the network
address are all set to 1, though it would also work if the bits were set
exactly as in the network address.) In this case, the subnet mask is
11111111.11111111.11110000.00000000.
It is called a mask because it can be used to identify the subnet to
which an IP address belongs by performing a bitwise AND operation
on the mask and the IP address. The result is the subnetwork address:
Subnet Mask 255.255.240.000
11111111.11111111.11110000.00000000
IP Address 150.215.017.009
10010110.11010111.00010001.00001001
Subnet Address 150.215.016.000
10010110.11010111.00010000.00000000
switch
A device that filters and forwards packets between LAN segments.
Switches operate at the data link layer (layer 2) and sometimes the
network layer (layer 3) of the OSI Reference Model and therefore
support any packet protocol. LANs that use switches to join
segments are called switched LANs or, in the case of Ethernet
networks, switched Ethernet LANs. A hub connects all the devices
on its “ports” together.
A switch is a bit smarter, as it understands when two devices (out of
four, five, eight, sixteen, or even more) want to talk to each other and
gives them a switched connection.
symbolic name
A name corresponding to a single interface. This name uniquely
identifies the interface on a controller or gateway. If there is more
than one interface on the controller or gateway, each interface must
have a unique symbolic name.