Technical Manual
U-SYS MRS6100 Media Resource Server
Chapter 5 MGCP and SIP
Huawei Technologies Proprietary
5-32
6) Event 6: MGC sends a DLCX command to MRS, requesting to delete the entire
conference. If the command does not contain a connection identifier, it indicates
the entire conference is to be deleted. Or a specified party of the conference is to
be deleted.
z
DLCX encoding
DLCX 171000299 ms/cnf/[email protected] MGCP 1.0
z
DLCX ACK encoding
250 171000292 OK
P:PS=300,OS=3000,PR=1000,OR=10000,PL=0,JI=0,LA=0
5.3 SIP
5.3.1 Basic Concepts
Put forward and studied by the IETF, Session Initiation Protocol (SIP) is an
application-layer control protocol for multimedia communication over IP network,
which can be used for creating, modifying and terminating sessions with one or more
participants. These sessions include Internet multimedia conferences, Internet
telephone calls, distance learning, telemedicine, and similar applications.
Multimedia sessions refer to two-party or multiparty interactive multimedia
communication activities on the Internet. Participants in a session can communicate
through multicast or through a mesh of unicast relations. Alternatively, they can
communicate through a combination mode of these two.
SIP learns from design concepts of other Internet standards and protocols and follows
Internet principles including the concision, openness, compatibility and expandability,
with security issues taken into account. On the other hand, SIP comprehensively
provides support to traditional PSTN services including IN and ISDN services.
SIP invitations with session descriptions are used to create sessions, which allow
participants to agree on a set of compatible media types. The protocol supports user
mobility by sending proxy and redirecting requests to the user’s current location.
Users can also register their current locations. SIP is not tied to any particular
conference control protocol. It is also designed to be independent of the lower-layer
transport protocol, so SIP can be extended with additional functions.
Being an application-layer multimedia session protocol, SIP can be used to initiate
sessions, as well as inviting members to sessions that have been advertised and
established by other means. Sessions can be advertised using multicast protocols
such as Session Announcement Protocol (SAP), electronic mail, web pages or
Lightweight Directory Access Protocol (LDAP). SIP supports name mapping and
redirection services, allowing the implementation of ISDN and IN services. These
facilities also enable personal mobility, that is, the ability of end users to request and