Copyright © 2004-2005, Vivato, Inc.
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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 reestablishes 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
STP
Shielded Twisted Pair (STP) is a type of copper conductor cable where each of the two copper wires that
are twisted together are coated with a shield that functions as a ground for the wires. This shield protects
the cable from electromagnetic interference that otherwise could get into or out of the cable.
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:
Supported Rate Set
The
supported rate set
defines the transmission rates that are available on this wireless network. A station
may be able to receive data at any of the rates listed in this set. All stations must be able to receive data at
the rates listed in the
TCP
The
Transmission Control Protocol
(TCP) is built on top of Internet Protocol (
). It adds reliable
communication (guarantees delivery of data), flow-control, multiplexing (more than one simultaneous
connection), and connection-oriented transmission (requires the receiver of a packet to acknowledge
receipt to the sender). It also guarantees that packets will be delivered in the same order in which they
were sent.
TCP/IP
The Internet and most local area networks are defined by a group of protocols. The most important of
these is the
Transmission Control Protocol over Internet Protocol
(TCP/IP), the de facto standard
protocols. TCP/IP was originally developed by Defense Advanced Research Projects Agency (DARPA,
also known as ARPA, an agency of the US Department of Defense).
and
are two specific protocols, TCP/IP is often used to refer to the entire protocol suite
based upon these, including ICMP, ARP,
, and others, as well as applications that run upon these
protocols, such as telnet, FTP, etc.
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
