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TCP/IP Tutorial and Technical Overview - IBM Redbooks

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Receiver report An R<strong>TCP</strong> receiver report provides reception<br />

statistics for participants that are not active<br />

senders. A sender report is issued if a device has<br />

sent any data packets during the interval since<br />

issuing the last report; otherwise, a receiver report<br />

is issued.<br />

Source description report A source description packet is used by an RTP<br />

sender to provide local capability information. The<br />

currently defined source descriptions include:<br />

764 <strong>TCP</strong>/<strong>IP</strong> <strong>Tutorial</strong> <strong>and</strong> <strong>Technical</strong> <strong>Overview</strong><br />

CNAME A unique name for the source<br />

NAME The real name of the source<br />

EMAIL The e-mail address of the application<br />

user<br />

PHONE The phone number of the application<br />

user<br />

LOC The geographic location of the<br />

application user<br />

TOOL The specific application or tool name<br />

NOTE Additional notes about the source<br />

PRIV Private extensions<br />

BYE The R<strong>TCP</strong> bye message is used by a source when<br />

it leaves a conference. This is used when a mixer<br />

shuts down. The BYE message is used to indicate<br />

all sources contributing to the session.<br />

APP The APP packet is intended for experimental use<br />

as new applications <strong>and</strong> features are developed.<br />

After testing <strong>and</strong> if wider use is justified, it is<br />

recommended that each APP packet be registered<br />

with the Internet Assigned Numbers Authority.<br />

R<strong>TCP</strong> packet format<br />

Figure 21-8 on page 765 shows the format of a R<strong>TCP</strong> sender report. The report<br />

is grouped in three sections. The first section contains the header. This section<br />

specifies the packet type, length, <strong>and</strong> sender identification.<br />

The second section contains sender information. The third section contains<br />

receiver report blocks. The packet can contain several receiver report blocks.<br />

This enables the sender to report feedback from RTP packets received from<br />

other senders.

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