Edgewater Networks 4300T Uživatelský manuál stáhnout pdf (Strana 49)

Local Area Network (LAN) Architecture

Page 49 of 51

Definitions

The following definitions may assist with understanding terminology used within this document.

ALG

Application Layer Gateway. The component within an EdgeMarc that provides the base VoIP functionality,

including private-to-public IP address translation and inbound dial-number mappings.

DHCP

Dynamic Host Configuration Protocol. Protocol for assignment of IP addresses to devices. Used to assign

unique IPs to LAN devices such as PCs and Phones. One DHCP server is allowed per Ethernet (Virtual)

LAN.

802.1 Framing

Standard Ethernet header framing. Used in flat (non-VLAN) Ethernet networks.

802.1q Framing

Extension to Ethernet framing used in VLAN (Virtual LAN) networks. Provides a VLAN ID in the header of the

Ethernet packet. Ethernet links that include the 802.1q tag are sometimes called Trunk links.

Firewall

A piece of hardware and/or software which functions in a networked environment to prevent

Some communications forbidden by the security policy

LAN

Local Area Network. A computer network covering a local area, like a home, office, or building. Current LANs

are most likely to be based on switched IEEE 802.3 Ethernet running at 10, 100 or 1,000 Mbit/s or on wireless

technology

MOS

Mean Opinion Score. A measurement of quality of the audio heard by the listener on a phone

call. Scores range from 1 to 4.4. Toll quality audio is generally considered to have a MOS rating of 4 and

above

NAT

Network Address Translation (also including Port Address Translation when used in this document). Allows

one public IP address to be shared by many LAN-side endpoints, each having unique private IP addresses.

When active, NAT will change the Layer-3 IP address and/or Layer-4 Port number after a packet has been

generated by another device. This action often breaks VoIP protocols.

Proxy

Many definitions, but as used in this document refers to the address translation function of the EdgeMarc’s

ALG. The phones on the LAN side of the EdgeMarc view the EM as the softswitch; the softswitch sees the

Edgemarc’s WAN IP address as a large multi-line phone. The ALG performs an IP address translation

function and a phone number mapping function to translate VoIP signaling protocol and audio RTP from one

side of the EdgeMarc to the other.

SIP

Session Initiation Protocol. An IP telephony signaling protocol developed by the IETF. Primarily used for voice

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Edgewater Networks 4300T Uživatelský manuál Strana 49