Axis 206 User Manual page 38

AXIS 206 - Glossary
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multipoint serial connection. It enables the configuration of
inexpensive local networks and multidrop communications
links. It offers high data transmission speeds (up to
10Mbit/s), and as it uses a differential balanced line over
twisted pair (like RS-422), it can span relatively large
distances (4000 feet or 1200 meters). RS-485 only specifies
the electrical characteristics of the driver and the receiver. It
does not specify or recommend any data protocol.
Router - A device that determines the next network point to
which a packet should be forwarded on its way to its final
destination. A router creates and/or maintains a special
routing table that stores information on how best to reach
certain destinations. A router is sometimes included as part
of a network switch. See also Switch.
Security surveillance - Network video's advanced
functionality makes it highly suited to the applications
involved in security surveillance. The flexibility of digital
technology enhances security personnel's ability to protect
people, property and assets. Such systems are therefore an
especially attractive option for companies currently using
CCTV.
Server - In general, a server is a computer program tha
provides services to other computer programs in the same or
other computers. A computer running a server program is
also frequently referred to as a server. In practice, the server
may contain any number of server and client programs. A
web server is the computer program that supplies the
requested HTML pages or files to the client (web browser).
Sharpness - This is the control of fine detail within a
picture. This feature was originally introduced into color TV
sets that used notch filter decoders. This filter took away all
high frequency detail in the black and white region of the
picture. The sharpness control attempted to put some of that
detail back in the picture. Sharpness controls are mostly
superfluous in today's high-end TVs. The only logical
requirement for it nowadays is on a VHS machine.
Simplex - In simplex operation, a network cable or
communications channel can only send information in one
direction. See also Full-duplex.
SMTP (Simple Mail Transfer Protocol) - Used for sending
and receiving e-mail. However, as it is "simple," it is limited
in its ability to queue messages at the receiving end, and is
usually used with one of two other protocols, POP3 or
IMAP. These other protocols allow the user to save messages
in a server mailbox and download them periodically from
the server.
SMTP authentication - An extension of SMTP, where the
client is required to log into the mail server before or during
the sending of email. It can be used to allow legitimate users
to send email while denying the service to unauthorized
users, such as spammers.
SNMP (Simple Network Management Protocol) - SNMP
forms part of the Internet Protocol suite, as defined by the
Internet Engineering Task Force. The protocol can support
monitoring of network-attached devices for any conditions
that warrant administrative attention.
Sockets - Sockets are a method for communication between
a client program and a server program over a network. A
socket is defined as "the endpoint in a connection." Sockets
are created and used with a set of programming requests or
"function calls" sometimes called the sockets application
programming interface (API).
SSL/TSL
(Secure Socket Layer/Transport Layer Security) - These
two protocols (SSL is succeeded by TSL) are cryptographic
protocols that provide secure communication on a network.
SSL is commonly used over HTTP to form HTTPS, as used
e.g. on the Internet for electronic financial transactions. SSL
uses public key certificates to verify the identity of the
server.
Subnet & subnet mask - A subnet is an identifiably
separate part of an organization's network. Typically, a
subnet may represent all the machines at one geographic
location, in one building, or on the same local area network
(LAN). Having an organization's network divided into
subnets allows it to be connected to the Internet with a
single shared network address.
The subnet mask is the part of the IP address that tells a
network router how to find the subnet that the data packet
should be delivered to. Using a subnet mask saves the router
having to handle the entire 32-bit IP address; it simply
looks at the bits selected by the mask.
Switch - A network device that connects network segments
together, and which selects a path for sending a unit of data
to its next destination. In general, a switch is a simpler and
faster mechanism than a router, which requires knowledge
about the network and how to determine the route. Some
switches include the router function. See also Router.
TCP (Transmission Control Protocol) - TCP is used along
with the Internet Protocol (IP) to transmit data as packets
between computers over the network. While IP takes care of
the actual packet delivery, TCP keeps track of the individual
packets that the communication (e.g. requested a web page
file) is divided into, and, when all packets have arrived at
their destination, it reassembles them to re-form the
complete file.
TCP is a connection-oriented protocol, which means that a
connection is established between the two end-points and is
maintained until the data has been successfully exchanged
between the communicating applications.
Telnet - Telnet is a simple method with which to access
another network device, e.g. a computer. The HTTP protocol
and the FTP protocols allow you to request specific files
from remote computers, but do not allow you logon as a
user of that computer. With Telnet, you log on as a regular
user with whatever privileges you may have been granted
for specific applications and data residing on that computer.