Chapter 3 Services
of the multicast technology is to copy the packet at the nearest
place to the receiver.
Functions
Multicast provides the following functions:
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Reduce the server load. The server does not need to process
the request of each user.
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Save the network bandwidth. Reduce the network equipment
requirements.
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The user scale is flexible. Enlarging the user scale does not
bring extra load on the network bandwidth.
Principle
The source host sends data whose destination address is the ad-
dress of the multicast group. All receivers in the multicast group
can receive the same data copy. Other hosts in the network cannot
receive the data except the host (destination host) in the multicast
group. The multicast group is identified with Type D
address
(224.0.0.0 – 239.255.255.255).
Multicast Modes
To adapt to various environments, FSAP 9800 supports the follow-
ing multicast modes:
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snooping
In IGMP snooping mode, the system is not responsible for man-
aging the status of multicast members. It only passively imple-
ments IGMP message snooping and forwarding. It has a little
influence on the system load. However, it greatly increases
protocol processing load of the uplink equipment.
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IGMP proxy
In IGMP proxy mode, the system manages the status of mul-
ticast members actively, efficiently reducing the protocol load
of the uplink device.
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IGMP router
The IGMP router mode is a simplified proxy mode. In case the
multicast service is sent to the uplink port, the system does
not require uplink port for multicast service dynamically.
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Controlled multicast
The controlled multicast refers to control multicast service
packets. It implements user management and service man-
agement of multicast services, including the following:
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Multicast authorization and accounting
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Multicast monitoring and analysis
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Multicast
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Multicast encryption
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Multicast address assignment
FSAP 9800 supports controlled multicast technology on the ba-
sis of complete compliance with the standard multicast proto-
col.
When a user joins one multicast group, FSAP 9800 authorizes
the user and decides whether to take the user into the multicast
group depending on the authorization result.
This is called
multicast authorization.
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