Discover 5 Basics Of IP Telephony – #2 – Network Layer

Discover 5 Basics Of IP Telephony – #2 – Network Layer

At the network level, routing takes place, respectively, the main devices of the network layer are routers. It is here that determines how the data will reach the recipient with a specific IP address.

The main routed protocol is IP (Internet Protocol), on the basis of which IP telephony is built, as well as the worldwide Internet. There are also many dynamic routing protocols, the most popular among them is OSPF (Open Shortest Path First), an internal protocol based on the current state of communication channels.

To date, there are special VoIP-gateways (Voice Over IP Gateway), providing the connection of conventional analog phones to the IP-network. As a rule, they also have an integrated router that allows you to keep track of traffic, authorize users, automatically give out IP addresses, manage the bandwidth.

Among the standard functions of VoIP gateways are:

  • Security functions (creation of access lists, authorization);
  • Facsimile support;
  • Voicemail support;
  • Support for H.323, SIP (Session Initiation Protocol) protocols.

To deal with possible delays in the transmission of IP, it is necessary to supplement with additional means, for example, prioritization protocols (so that voice data does not compete with conventional ones).

Typically, for this purpose, routers use a low latency queuing (LLQ) or a weighted queuing based on classes (CBWFQ-Class-Based Weighted Fair Queuing).

In addition, priority labeling schemes are needed to treat voice data as the most important for transmission.

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