See RFC1889:
marker (M): 1 bit
The
interpretation of the marker is defined by a profile. It is
intended to allow
significant events such as frame boundaries to
be marked in the
packet stream. A profile may define additional
marker bits or
specify that there is no marker bit by changing
the number of
bits in the payload type field (see Section 5.3).
:
5.3 Profile-Specific
Modifications to the RTP Header
The existing RTP data
packet header is believed to be complete for
the set of functions
required in common across all the application
classes that RTP might
support. However, in keeping with the ALF
design principle, the
header may be tailored through modifications or
additions defined in a
profile specification while still allowing
profile-independent
monitoring and recording tools to function.
o The marker bit
and payload type field carry profile-specific
information, but
they are allocated in the fixed header since
many
applications are expected to need them and might otherwise
have to add
another 32-bit word just to hold them. The octet
containing these
fields may be redefined by a profile to suit
different
requirements, for example with a more or fewer marker
bits. If there
are any marker bits, one should be located in
the most
significant bit of the octet since profile-independent
monitors may be
able to observe a correlation between packet
loss patterns
and the marker bit.
ITU G.729 might hold
further information.
Regards
Anders
Från:
wireshark-users-bounces@xxxxxxxxxxxxx
[mailto:wireshark-users-bounces@xxxxxxxxxxxxx] För Boaz Galil
Skickat: den 29 juli 2009 17:37
Till: Community
support list for Wireshark
Ämne: [Wireshark-users] What does
it mean the "Mark" string under theinfo in RTP packets?
I am reviewing G729 packet stream. I have noticed that I have
lots of packets that have the string "Mark" in the info field.
Guy/or any other expert - can you please share some information about
the "Mark" string?
--
Boaz.
