Glossary

Routing

Routing is the transmission of data packets to another subscriber in your network. On its way to the recipient, the data packet is sent from one router to the next until it reaches its destina- tion.

If data packets were not forwarded in this way, a network like the Internet would not be possible. Routing connects the individual networks to this global system.

A router is a part of this system; it transmits data packets both within a local network and from one network to the next. Transmission of data from one network to another is performed on the basis of a common protocol.

RTP

Realtime Transport Protocol

Global standard for transferring audio and video data. Often used in conjunction with UDP. In this case, RTP packets are embedded in UDP packets.

RTP port

(Local) Port which is used to send and receive voice data packets for VoIP.

S

Server

Provides a service to other Network subscribers (Clients). The term can indicate a computer/PC or an applica- tion. A server is addressed via

IP address/Domain name and Port.

SIP (Session Initiation Protocol) Signalling protocol independent of voice communication. Used for establishing and ending a call. It is also possible to define parameters for voice transmission.

SIP address

See URI.

SIP port/Local SIP port

(Local) Port which is used to send and receive SIP signalling data for VoIP.

SIP providerSee VoIP provider.SIP proxy server

IP address of your VoIP provider's gateway server.

Static IP address

A static IP address is assigned to a network component manually during network configuration. Unlike a Dynamic IP address, a static (fixed) IP address never changes.

STUN

Simple Transversal of UDP over NAT

NAT control mechanism.

STUN is a data protocol for VoIP tele- phones. STUN replaces the private IP address in the data packets of the VoIP telephone with the public address of the secure private network. To control data transfer, a STUN server is also required on the Internet. STUN cannot be implemented with symmetric NATs.

See also: ALG, Firewall, NAT,

Outbound proxy.Subnet

Segment of a Network.

Subnet mask

IP address consist of a fixed network number and a variable subscriber number. The network number is identical for all Network subscribers. The proportion of the IP address made up of the network number is determined in the subnet mask. For the subnet mask 255.255.255.0, for example, the first three parts of the IP address are the network number and the last part is the subscriber number.

Symmetric NAT

A symmetric NAT assigns different external IP addresses and port numbers to the same internal IP addresses and port numbers – depending on the external target address.

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