Moxa Technologies Moxa EtherDevice Switch EDS-508 - Manual (Page 56)

EDS-508 Series User’s Manual Featured Functions
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VLAN Table
In this table, you can review the created VLAN groups, Joined Access Ports, and Trunk Ports.
NOTE The entire physical connected network system can have a maximum of 64 VLANs settings.
Using Multicast Filtering
Multicast filtering improves the performance of networks that carry multicast traffic. This section
explains multicasts, multicast filtering, and how multicast filtering can be implemented on your
EDS.
The Concept of Multicast Filtering
What is an IP Multicast?
A multicast is a packet that is intended for “one-to-many” and “many-to-many” communication.
Users explicitly request to participate in the communication by joining an end-station to a specific
multicast group. If the network is set up correctly, a multicast can only be sent to an end-station or
a subset of end-stations in a LAN, or VLAN, that belong to the relevant multicast group. Multicast
group members can be distributed across multiple subnetworks; thus, multicast transmissions can
occur within a campus LAN or over a WAN. In addition, networks that support IP multicast send
only one copy of the desired information across the network until the delivery path that reaches
group members diverges. It is only at these points that multicast packets are replicated and
forwarded, making more efficient use of network bandwidth. A multicast packet is identified by
the presence of a multicast group address in the destination address field of the packet’s IP header.
Benefits of Multicast
The benefits of using IP multicast are that it:
# Enables the simultaneous delivery of information to many receivers in the most efficient,
logical way.
# Reduces the load on the source (for example, a server) because it does not need to produce
multiple copies of the same data.
# Makes efficient use of network bandwidth and scales well as the number of participants or
collaborators expands.
# Works with other IP protocols and services, such as Quality of Service (QoS).
There are situations where a multicast approach is more logical and efficient than a unicast
approach. A typical use of multicasts is in video-conferencing, where high volumes of traffic need
to be sent to several end-stations simultaneously, but where broadcasting that traffic to all
end-stations would seriously reduce network performance. Besides, several industrial automation
protocols, such as Allen-Bradley, EtherNet/IP, Siemens Profibus, and Foundation Fieldbus HSE
(High Speed Ethernet), use the multicast approach. These industrial Ethernet protocols use