1/5/2007
EAG Gateway Series Administration Guidelines
MAG-06007 Rev. A
NAT (Network Address Translator or Translation)
Network Address Translation, an Internet standard that enables a local-area network (LAN) to use one
set of IP addresses for internal traffic and a second set of addresses for external traffic. A NAT box
located where the LAN meets the Internet makes all necessary IP address translations.
SDP (Session Description Protocol)
SDP describes multimedia sessions for the purpose of session announcement, session invitation and
other forms of multimedia session initiation.
STUN (Simple Traversal of UDP over NATs)
A protocol that allows applications to detect that a network address translation (NAT) is being used. It
can also detect the type of NAT and IP address assigned by it. STUN was developed to support
interactive, two-way communications over the Internet such as for voice (VoIP) and videoconferencing.
The STUN client sends requests to a STUN server, which is typically hosted by the service provider.
Unlike application layer gateways (ALGs) and Middlebox Communications (MIDCOM), which also
support two-way communications through NATs, STUN requires no changes to the NAT.
RADIUS (Remote Authentication Dial In User Service)
Remote Authentication Dial-In User Service (RADIUS) is a client/server protocol and software that
enables remote access servers to communicate with a central server to authenticate dial-in users and
authorize their access to the requested system or service. RADIUS allows a company to maintain user
profiles in a central database that all remote servers can share. It provides better security, allowing a
company to set up a policy that can be applied at a single administered network point. Having a central
service also means that it's easier to track usage for billing and for keeping network statistics. Created
by Livingston (now owned by Lucent), RADIUS is a de facto industry standard used by a number of
network product companies and is a proposed IETF standard.
RADIUS Server
RADIUS Server authenticates clients and returns corresponding settings.
Signal Gain
When detected signals are not strong enough over the network, we use signal gain parameter to
increase the strength of the signal.
Line Impedance
A measure of the total opposition to current flow in an alternating current circuit, made up of two
components, ohmic resistance and reactance, and usually represented in complex notation as Z = R +
iX, where R is the ohmic resistance and X is the reactance. It also refers to an analogous measure of
resistance to an alternating effect, as the resistance to vibration of the medium in sound transmission.
Signal Mode
Signal mode refers to inserting a silence signal periodically into the voice stream. Standard used in
China specifies “450 Hz, 350ms ON + 350ms OFF”, means signal cycle is 700ms; insert 350 ms signal
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