Switching Hub Types; Switching Hub Functions; Precautions When Selecting A Switching Hub - Omron CS1W-EIP21 Operation Manual

Selecting the Network Devices
Part Maker
Connectors STP Plug
(Modular
Panduit Corporation
plug)
UTP Plug
Panduit Corporation
Boots Tsuko Company
Note
2-2-2

Switching Hub Types

Layer 2 (L2) Switching
Hub
Layer 3 (L3) Switching
Hub
2-2-3

Switching Hub Functions

Multicast Filter
Layer 3/4 QoS (Quality of
Service) Function
2-2-4

Precautions When Selecting a Switching Hub

28
Model number
MPS588
MP588-C
MK boot (IV) LV
(1) Always use a switching hub when using tag data links in the network.
(2) If a repeater hub is used for EtherNet/IP tag data links (cyclic communi-
cations), the network's communications load will increase, data collisions
will occur frequently, and stable communications will be impossible.
These switching hubs use the Ethernet MAC address to switch ports. Ordi-
nary switching hubs have this function.
These switching hubs use the Ethernet MAC address or IP address to switch
ports. When using an EtherNet/IP Unit, select from the following functions.
• L2 switch without multicast filtering function
• L2 switch with multicast filtering function
• L3 switch with multicast filtering function and L2/L3 QoS function
This section describes the switching hub functions which are important when
using an EtherNet/IP network.
The multicast filter transfers multicast packets to the specific nodes only. This
function is implemented in the switching hub as IGMP Snooping or GMRP.
"Specific nodes" are nodes equipped with an IGMP client that have made
transfer requests to the switching hub. (OMRON EtherNet/IP Units are
equipped with an IGMP client.)
When the hub does not use the multicast filter, multicast packets are sent to
all nodes, just like broadcast packets, which increases the traffic in the net-
work. Settings must be made in the switching hub to enable this function.
This function controls the priority of packet transmissions, so that packets can
be sent with higher priority to a particular IP address and TCP (UDP) port.
When tag data links and message communications are executed on the same
network, tag data links can be sent at higher priority to prevent problems such
as transmission delays due to message communications traffic and packet
losses due to buffer overflow. Settings must be made in the switching hub to
enable this function and give higher priority to tag data link packets.
The functions supported by the switching hub may affect tag data link trans-
mission delays and the configuration. In addition, if the switching hub supports
advanced functions, special settings are required for those functions.
Section 2-2
Inquires
Panduit Corporation US Headquar-
ters: (800) 777-3300
Panduit Corporation US Headquar-
ters: (800) 777-3300
Tsuko Company Japan Headquar-
ters 011-81 (03) 3542-2781