Filter
Top Products
115
HomePortal 3801HGV Gateway User Guide Glossary
NAT (Network Address
Translation)
Enables a LAN to use one set of IP addresses for internal traffic and a second set of
IP addresses for external traffic. This feature is used by the system so an end user
can have an internal computer network in their home, with all its computers using
internal IP addresses, using only one routable IP address, which accesses the
outside (Internet).
PAT (Port Address Translation) Allows hosts on a LAN to communicate with the rest of a network (such as the
Internet) without revealing their own private IP address. All outbound packets have
their IP address translated to the router’s external IP address. Replies come back to
the router, which then translates them back into the private IP address of the original
host for final delivery.
PPP (Point-to-Point Protocol) A protocol that allows a computer to access the Internet using a dial-up phone line
and a high-speed modem. This can be accomplished over Ethernet (PPPoE), or over
Asynchronous Transfer Mode (ATM; PPPoA).
PPPoA (Point-to-Point Protocol
over ATM)
A specification for connecting multiple computer users on an Ethernet LAN to a
remote site through common customer premises equipment (such as a modem).
PPPoA combines the Point-to-Point Protocol (PPP), commonly used in dialup
connections, with the ATM (Asynchronous Transfer Mode) protocol, which supports
multiple users in a LAN.
PPPoE (Point-to-Point Protocol
over Ethernet)
A specification for connecting multiple computer users on an Ethernet LAN to a
remote site through common customer premises equipment (such as a modem).
PPPoE combines the Point-to-Point Protocol (PPP), commonly used in dialup
connections, with the Ethernet protocol, which supports multiple users in a LAN.
Protocol Timeout The amount of time (in seconds) during which a connection in the specified range
remains open when there is no data transfer. After a connection has been established
on a given port, the sender and receiver usually determine when the session is
finished and the connection is closed. However, if the connection is left open and data
transfer stops, the system must eventually close the connection and reclaim the
resources in order to protect your network. In some cases, the system might close the
application during normal operation (for example, if there is a long pause between
data transfer). If this is the case, lengthening the timeout may help.
PVC (permanent virtual circuit) A virtual circuit that is permanently available. Used to establish connections between
hosts that communicate frequently.
Router The central switching device in a packet-switched computer network that directs and
controls the flow of data through the network.
Subnet Mask The IP addressing system allows subnetworks or “interchanges” to be created, and
devices numbers or “extensions” to be established within these subnetworks. These
numbers are created using a mathematical device called a subnet mask. A subnet
mask, like the IP address, is a set of four numbers in dotted decimal notation. Subnet
masks typically take three forms:
• 255.0.0.0
• 255.255.0.0
• 255.255.255.0
The number 255 “masks” out the corresponding number of the IP address, resulting
in IP address numbers that are valid for the network. For example, an IP address of
123.45.67.89 and a subnet mask of 255.255.255.0 results in a sub network number of
123.45.67.0 and a device number of 89.
The subnet mask used for the network typically corresponds to the class of IP
address assigned, as shown in the following table:
Term Description
IP Address
Class
Dotted-
Decimal
Notation
Ranges
Corresponding
Subnet Mask
Class A 1.xxx.xxx.xxx to
126.xxx.xxx.xxx
255.0.0.0
Class B 128.0.xxx.xxx to
191.255.xxx.xxx
255.255.0.0
Class C 192.0.0.xxx to
223.255.255.xx
x
255.255.255.0