Multicast Models - H3C s3100-52P Operation Manual

Operation Manual – Multicast
H3C S3100-52P Ethernet Switch
Multicast provides the following applications:
Applications of multimedia and flow media, such as Web TV, Web radio, and
real-time video/audio conferencing.
Communication for training and cooperative operations, such as remote
education.
Database and financial applications (stock), and so on.
Any point-to-multiple-point data application.

1.2 Multicast Models

Based on the multicast source processing modes, there are three multicast models:
Any-source multicast (ASM)
Source-filtered multicast (SFM)
Source-specific multicast (SSM)
I. ASM model
In the ASM model, any sender can become a multicast source and send information to
a multicast group; numbers of receivers can join a multicast group identified by a group
address and obtain multicast information addressed to that multicast group. In this
model, receivers are not aware of the position of a multicast source in advance.
However, they can join or leave the multicast group at any time.
II. SFM model
The SFM model is derived from the ASM model. From the view of a sender, the two
models have the same multicast group membership architecture.
Functionally, the SFM model is an extension of the ASM model. In the SFM model, the
upper layer software checks the source address of received multicast packets so as to
permit or deny multicast traffic from specific sources. Therefore, receivers can receive
the multicast data from only part of the multicast sources. From the view of a receiver,
multicast sources are not all valid: they are filtered.
III. SSM model
In the practical life, users may be interested in the multicast data from only certain
multicast sources. The SSM model provides a transmission service that allows users to
specify the multicast sources they are interested in at the client side.
The radical difference between the SSM model and the ASM model is that in the SSM
model, receivers already know the locations of the multicast sources by some means.
In addition, the SSM model uses a multicast address range that is different from that of
the ASM model, and dedicated multicast forwarding paths are established between
receivers and the specified multicast sources.
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Chapter 1 Multicast Overview