Precautions For Ethernet Switch Selection - Omron NX Series User Manual

5 Installing Ethernet Networks
Ethernet switch type
Unmanaged L2 Ethernet switch
Managed L2 Ethernet switch
OMRON Ethernet switch
(W4S1-series Ethernet switches)
*1. Even QoS settings are made, tag data links and CIP Safety communications are processed with the
same priority.
Additional Information
• If you select Multi-cast Connection for the connection type in the connection settings on the
Network Configurator, multicast packets are used. If the connection type is set to a Point to
Point Connection, multicast packets are not used.
5-1-4

Precautions for Ethernet Switch Selection

The functions supported by the Ethernet switch may affect tag data link transmission delays and the
settings in the Controller configurations and setup.
In addition, if the Ethernet switch supports advanced functions, special settings are required for the
functions.
When you select an Ethernet switch, it is necessary to consider what kind of data transmission and
how much traffic you use over the the network.
Refer to the following precautions when you select an Ethernet switch.
Refer to 12-2 Adjusting the Communications Load on page 12-7 to estimate the communications
load for tag data links.
Selecting the Ethernet Switch Based on the Type of Network Com-
munications
l Executing Tag Data Links Only
We recommend that you use an L2 Ethernet switch without multicast filtering or an L2 Ethernet
switch with multicast filtering.
An L2 Ethernet switch with multicast filtering prevents increased traffic due to unnecessary multi-
cast packets, so the tag data links can operate at higher speed.
If either of the following conditions exists, there is no difference in the traffic condition whether mul-
ticast filtering is supported or not.
• The tag data links are set to share the same data with all nodes in the network. (Multicast pack-
ets are transferred to all nodes in the network, just like broadcast transmission.)
• The tag data link settings are all one-to-one (unicast) and multicast packets are not used.
When multicast filtering is used, settings must be made accordingly on the Ethernet switch. There
must be enough multicast filters for the network.
l Executing Tag Data Links and Message Communications
We recommend an L2 Ethernet switch with multicast filtering and L4 QoS.
5-4
Multicast filtering L4 QoS
Not supported Not sup-
ported
Supported Supported
Not supported Supported
NX-series EtherNet/IP Unit User's Manual (W627)
Remarks
---
Both functions must be set
with a special software tool.
L4 QoS is set with a switch.
No software tool is necessa-
*1
ry.