Huawei U-SYS MRS6100 Technical Manual page 76

Technical Manual
U-SYS MRS6100 Media Resource Server
The 13th line: Null. It indicates what is preceded is an SDP session description.
The 14th line: This is the SDP protocol version number. At present, it is the version 0.
The 15th line: This line contains the session owner/creator and the session identifier,
used to give the initiator (username and host address) of the session, the session
identifier, and the session version number. UNICA is the username that is used by the
user to log into the originating host. If the host does not support user ID, this field is
tagged to be a sign (-). The first 1073741831 is the session identifier. The session
identifier in the form of a digit string helps the multiple tuples (username, session
identifier, network type, address type, and address) to construct the globally unique
identifier of the session. The second 1073741831 is the version number of the
session announcement, which is provided for the proxy server to detect the latest one
from the several announcements of the same session. The basic principle is to
increment that version number once the session data is modified. IN refers to the
network indicator in the form of a text string. The currently defined IN is Internet. IP4
refers to the address type in the form of a text string. At present, IP4 and IP6 are
defined. 182.20.20.105 is the IP address of the host that creates the session.IP4
addresses can be expressed in full domain name or dotted decimal notation.IP6
addresses can be expressed in full domain name or compressed file form.
The 16th line: This line contains the session name. Each session description must
have one and only one session name.
The 17th line: This line contains the connection related data. At present, the network
type and the address type are defined to be IN and IP4. 182.20.70.1 may be the IP
address of an MG (the terminal type is ESL telephone connected to an IAD/AG) under
the control of the SoftX. 182.20.70.1 may also be the IP address of a SIP or H.323
terminal (the terminal type is SIP or H.323 phone).
The 18th line: This line contains the time description. It provides a time segment when
the session can be activated, allowing the session to periodically occur. The 0
represents the start time. The format for the field is t:<start time><end time>. The
values of start time and end time are expressed in the decimal form of network time
protocol (NTP) time values. The unit is second.
The 19th line: This line contains the media-level description. It provides information
that is suitable only for the media stream. The audio refers to the media type. At
present, five types of media are defined: audio, video, application, data, and control.
30000 represents the transport-layer port to which the media stream is transmitted,
that is, the UDP port number of the MG (the terminal type is ESL phone connected to
an IAD/AG) or the UDP port number of a SIP or H.323 terminal (the terminal type is
SIP or H.323 phone). RTP/AVP is the transport-layer protocol. Its value is associated
with the type of address in the c line. For IP4, a great number of media service
streams are transferred over RTP/UDP. There are two classes of protocols defined:
RTP/AVP, audio/video application document, transported over UDP; Udp, the DUP
protocol. The 8 0 4 18 is, for audio and video, the media payload type that is defined in
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Chapter 5 MGCP and SIP