Usage of softswitch protocols 4 special protocols

The usage of softswitch protocol is described in four special protocols. Next we will give a brief introduction to several main Softswitch protocols, such as H.248/MEGACO, Media Gateway Control Protocol MGCP), and Session Initiation Protocol SIP.

Main protocols used by Softswitch

The softswitch system involves many Softswitch protocols, including H.248, SCTP, ISUP, TUP, INAP, H.323, RADIUS, SNMP, SIP, M3UA, MGCP, BICC, PRI, and BRI.

International organizations, such as IETF, ITU-T, and SoftSwitchOrg, have been actively leading the research on SoftSwitch and protocols. Many key protocols have been developed or tend to be completed. These Softswitch protocols will regulate the entire research and development of softswitch, so that the product enters the stage of using the proprietary protocols of various manufacturers to use the common standard protocols in the industry, and product intercommunication between different products becomes possible, the original intention of realizing Softswitch is to provide a standard and open system structure, and various network components can develop independently.

In terms of research progress of softswitch, China is at the level of global synchronization. In the second half of 1999, the "Network and exchange standards research group" of the Ministry of Information Industry started the research on the softswitch project, and has completed the "General Technical Requirements for Softswitch Equipment". In addition, the "IP standard research group" is developing a relay media gateway TG), signaling gateway? Point SG? Snow, Access Gateway AG), integrated access device? Point IAD? Technical specifications for snow and other equipment.

Next we will give a brief introduction to several main Softswitch protocols.

H.248/MEGACO

Both H.248 and MEGACO protocols are called media gateway control protocols and are applied between media gateway and H.248/MEGACO and SoftSwitch devices. The content of the two Protocols is basically the same, but H.248 is proposed by ITU, while MEGACO is proposed by IEFT and is also a Softswitch protocol jointly recommended by both parties. They introduce two abstract concepts: Termination terminal) and Context Association.

In the Termination terminal), the media stream parameters, MODEM, and bearer capacity parameters are encapsulated, while Context Association) indicates the connection between some Termination terminals.

H.248/MEGACO uses eight commands, including Add, Modify, Subtract, and Move, to establish and release the call between the Termination terminal and Context.

Media Gateway Control Protocol MGCP)

Media Gateway Control Protocol (MGCP) is proposed by IEFT and is a combination of simple Gateway Control Softswitch protocol (SGCP) and IP Device Control Protocol (IPDC. The MEGACO Protocol is further improved, improved, and improved for the MGCP protocol.

MGCP is a mature Softswitch protocol with similar content as MEGACO. At present, many devices in the softswitch system support this protocol, and its shortcomings are gradually manifested. In the future, it may be replaced by the H.248/MEGACO Protocol.

In the softswitch system, the MGCP protocol is the same as the H.248/MEGACO Protocol and is used between the media gateway and MGCP terminal and the softswitch device, this protocol is used to control the connection, establishment, and release of the Media/control flow on the media gateway and MGCP terminal.

Session Initiation Protocol (SIP)

Session Initiation Protocol (SIP) is an application layer control protocol proposed by IETF for multimedia communication over IP networks. Based on the Internet protocol HTTP), follow the Internet design principles, and work in peer-to-peer mode.

Using SIP, you can connect, establish, and release sessions, and support unicast, multicast, and mobility. In addition, if SIP is used with SDP, You can dynamically adjust and modify session attributes, such as call bandwidth, transmitted media type, and CODEC format. For details, see IETFRFC2543bis.

In the softswitch system, the SIP protocol is mainly used between the softswitch and the SIP terminal. Some manufacturers also apply the SIP protocol to the softswitch and the application server to provide value-added services based on the SIP protocol. In general, the SIP protocol is mainly used for voice and data-based businesses, as well as call establishment and release between multimedia businesses.

In particular, because of its simplicity and flexibility, the 3GPP, which serves as the mobile communication Standardization Organization, has decided to establish a full IP network for the third-generation mobile communication on its basis, in addition, it is required that 3G terminals support the SIP protocol in the future.

SCTP Protocol

SCTP is a traffic control transfer protocol proposed by IETF. PSTN signaling information is transmitted over a connectionless network. This protocol can provide reliable data transmission over the IP network. SCTP can transmit user data without errors and duplication in the confirmation mode, and segment user data according to MTU restrictions of the path;

Ensure that user messages are delivered sequentially in multiple streams, and copy the messages of multiple users to the data block of SCTP. Use the SCTP even connection mechanism to ensure self-handling of some faults at the network level. SCTP also avoids congestion and prevents flooding and anonymous attacks. SCTP plays a major role in controlling Softswitch protocols.