User Manual

Psion Teklogix 9160 Wireless Gateway User Manual E-25
Appendix E: Glossary
Static IP Address
Static IP Address
See IP Address.
STP
The Spanning Tree Protocol (STP) an IEEE 802.1 standard protocol (related to
network management) for MAC bridges that manages path redundancy and
prevents undesirable loops in the network created by multiple active paths between
client stations. Loops occur when there multiple routes between access points. STP
creates a tree that spans all of the switches in an extended network, forcing
redundant paths into a standby, or blocked, state. STP allows only one active path at
a time between any two network devices (this prevents the loops) but establishes the
redundant links as a backup if the initial link should fail. If STP costs change, or if
one network segment in the STP becomes unreachable, the spanning tree algorithm
reconfigures the spanning tree topology and re-establishes the link by activating the
standby path. Without spanning tree in place, it is possible that both connections
may be simultaneously live, which could result in an endless loop of traffic on the
LAN
Subnet Mask
A Subnet Mask is a number that defines which part of an IP address is the network
address and which part is a host address on the network. It is shown in dotted-
decimal notation (for example, a 24-bit mask is shown as
255.255.255.0 ) or as a
number appended to the IP address (for example,
192.168.2.0/24 ).
The subnet mask allows a router to quickly determine if an IP address is local or
needs to be forwarded by performing a bitwise AND operation on the mask and the
IP address. For example, if an IP address is
192.168.2.128 and the netmask is
255.255.255.0 , the resulting Network address is 192.168.2.0 .
The bitwise AND operator compares two bits and assigns 1 to the result only if both
bits are 1. The following table shows the details of the netmask:
IP address
192.168.2.128 11000000 10101000 00000010 10000000
Netmask
255.255.255.0 11111111 11111111 11111111 00000000
Resulting network address
192.168.2.0 11000000 10101000 00000010 00000000