Moxa Technologies PT-7728 User Manual

PT-7728 User’s Manual Featured Functions
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all end-stations would cause a substantial reduction in network performance. Furthermore, several
industrial automation protocols, such as Allen-Bradley, EtherNet/IP, Siemens Profibus, and
Foundation Fieldbus HSE (High Speed Ethernet), use multicast. These industrial Ethernet
protocols use publisher/subscriber communications models by multicasting packets that could
flood a network with heavy traffic. IGMP Snooping is used to prune multicast traffic so that it
travels only to those end destinations that require the traffic, reducing the amount of traffic on the
Ethernet LAN.
Multicast Filtering
Multicast filtering ensures that only end-stations that have joined certain groups receive multicast
traffic. With multicast filtering, network devices only forward multicast traffic to the ports that are
connected to registered end-stations. The following two figures illustrate how a network behaves
without multicast filtering, and with multicast filtering.
Network without multicast filtering
LNK/ACT SPEED FDX/HDX
FAULT MASTER COUPLER
STAT PWR1 PWR2
RING PORT
COUPLER
PORT
MODE
3
7
4 8
2
6
1
5
3
7
4
8
2 6
1
5
4
3
2
1
3
7
4
82
6
1
5
M1
M2
M3
M4
LNK/ACT SPEED FDX/HDX
FAULT MASTER COUPLER
STAT PWR1 PWR2
RING PORT
COUPLER
PORT
MODE
3 7
4 82
6
1
5
3
7
4 82 6
1
5
4
32
1
3 7
4
8
2
6
1 5
M1
M2
M3
M4
1
2
3
4
5
6
7
8
M3
PT-7728
M4
1
2
3
4
4
1
3
2
1
3
5
24
6
M1
TX
RX
TX
RX TX
RX
24
6
13
5
M2
TX
RX TX RX TX RX
All hosts receive the multicast traffic, even if they don’t need it.
Network with multicast filtering
IGMP Group2
Group 1 Multicast Stream Group 2 Multicast Stream
IGMP Group1 IGMP Group2 IGMP Group1
LNK/ACT SPEED FDX/HDX
FAULT MASTER COUPLER
STAT PWR1 PWR2
RING PORT
COUPLER
PORT
MODE
3
7
4 8
2
6
1
5
3
7
4
8
2 6
1
5
4
3
2
1
3
7
4
82
6
1
5
M1
M2
M3
M4
LNK/ACT SPEED FDX/HDX
FAULT MASTER COUPLER
STAT PWR1 PWR2
RING PORT
COUPLER
PORT
MODE
3 7
4 82
6
1
5
3
7
4 82 6
1
5
4
32
1
3 7
4
8
2
6
1 5
M1
M2
M3
M4
1
2
3
4
5
6
7
8
M3
PT-7728
M4
1
2
3
4
4
1
3
2
1
3
5
24
6
M1
TX
RX
TX
RX TX
RX
24
6
13
5
M2
TX
RX TX RX TX RX
Hosts only receive dedicated traffic from other hosts belonging to the same group.

Moxa Technologies PT-7728 Specifications

General

Brand	Moxa Technologies
Model	PT-7728
Category	Switch
Language	English