SIP Protocol Document Translation

SIP: Session Initiation Protocol

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This document has developed an Internet standard tracking protocol for Internet communications that asks for discussion and elevation of recommendations. Please refer to the "Official Internet Protocol Standard" for the standardized status of this agreement. Forward Unlimited!

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This document describes the Session Initiation Protocol (SIP), a protocol for creating, modifying, and terminating a session with an application layer control (signaling) of one or more participants. These sessions include Internet telephony, multimedia distribution, and multimedia conferencing.

SIP invitations are used to create session descriptions that allow participants to consent to a range of compatible media types. SIP uses a proxy server to request the user's current location (IP address), authenticate and authorize user Services, implement a provider call routing policy, and provide functionality to the user. SIP also provides registration functionality that allows users to load their current location from a proxy server. SIP runs at the top level of several transport protocols.

1 Introduction

There are many Internet applications that request session creation and management, in which sessions are treated as data interactions between participants ' communities. The implementation of these applications is complex: Users may move between two terminals, they may be addressable by multiple names, and they communicate in a different media format-sometimes at the same time. Many protocols are licensed to carry different forms of timely multimedia session data such as sound, video, or text messages. SIP is designed to reconcile these protocols by making Internet terminals (also called user agents) discover each other and agree on a session attribute they want to share. In order to identify the session participants, as well as other features, the SIP makes the basic construction of the network host (also known as the proxy server) created, and the user is able to send registrations, invitations to sessions, and other requests. SIP is a fast and versatile tool for creating, modifying, and terminating sessions that work independently of the underlying laundry and do not rely on the established session type.

Overview of 2.SIP functions

SIP is an application-layer protocol that can establish, modify, and terminate multimedia sessions (conferences) such as Internet telephony. SIP can also invite participants to a session that already exists, such as a multicast meeting. The media can be added (and deleted) to an existing session. SIP significantly supports name Mapping and redirection services, and also supports personalization moves--users can maintain a separate externally visible identifier regardless of their network location.

SIP supports five aspects of establishing and terminating multimedia communications:

User location: The terminal system is used for communication determination.

User validity: Determination of the willingness of the user being called to participate in the communication.

User performance: Determination of the media and media parameters being used.

Session settings: "Call", the establishment of a session parameter called and called a party.

Session Management: Includes the transfer and termination of sessions, modifying session parameters and requesting services.

SIP is not a vertically integrated communication system. SIP is a component that can be used to establish a complete multimedia architecture with other IETF (Internet Engineer Task Force: Internet Engineering Group) protocols. Typically, these architectures will contain feedback such as timely communication protocols (Real-ime Transport PROTOCOL:RTP) for transmitting timely data and providing quality of service (quality of Service:qos) The time Flow Protocol (RTSP) is used to control the transmission of streaming media, and the Media Gateway Control Protocol (MEGACO) is used to control the gateway to the public Switched telephone network (common switched telephone NETWORK:PSTN) and the session Description protocol Description PROTOCOL:SDP) is used to describe multimedia sessions. Therefore, in order to provide a complete service to the user, SIP should be used as a combination with other protocols. However, the basic functions and operations of SIP do not depend on any of these protocols.

SIP does not provide services. Of course, SIP provides primitives for implementing different services. For example, SIP can locate a user and transfer a non-transparent object to his current location. If this primitive is used to transmit the session description is written to the SDP (Sessiong Description Protocol), for example, the terminal can agree on the session parameters. The caller ID service can be easily implemented if the same primitive is used to transfer the caller's picture as a session description. As this example shows, a single primitive is typically used to provide several different services.

SIP does not provide a voice or voting control service, and does not stipulate how meetings are managed. SIP can be used to initiate a session that uses a different conferencing control protocol. Because SIP information and sessions that they establish can be transmitted over the entire Internet, SIP itself cannot and does not provide any kind of Internet resource retention functionality.

The nature of the service makes security particularly important. For this purpose, SIP provides a set of security services, including denial of service blocking, authorization (including user-to-user and agent-to-user), integrity containment, and encryption and privacy services.

SIP supports IPV4 and IPv6.

3 terminology

In this document, the keywords "must", "must not", "REQUIRED", "shall", "shall not", "should", "should not", "RECOMMENDED", "Not RECOMMENDED", " May "and" OPTIONAL "are interpreted as described by bcp 14,RFC 2119[2] and indicate the level of demand in order to obey the SIP implementation.

4 Operation Preview

SIP Protocol Document Translation