Installation guide

Network Infrastructure for EtherNet/IP™
A-6
Appendix A Recommendations for Ethernet Switches in EtherNet/IP Systems
Industrial System Maintainability
In addition to infrastructure-embedded functions, the use of plant-floor network management software
provides added plant maintainability, and compliments the IT-based network management software
already installed in many facilities. This type of software provides a simplified “PLC look” interface to
the entire EtherNet/IP industrial system. The system-wide view allows quick identification of non-
communicating devices, the centralized viewing of SNMP diagnostic “trap” messages, and the ability to
“zoom” into detailed device-specific diagnostics using network management screens or the device’s
embedded web pages. These packages also allow easy upload/download (via open Trivial File Transfer
Protocol [TFTP]) of switch/device configurations and upgrades. Because these packages use the industry
standards, such as SNMP protocol, network management software from one vendor can work with other
vendor’s switches.
The functions below relate to infrastructure (switch or router) embedded functions.
1. Alarm contact: The addition of a physical relay-out allows annunciation of power outages
and/or disabling of key links (cable cut, device powered down, etc). The alarm contact is
connected to either physical alarms, lights, etc., or to automation inputs (i.e., spare PLC
inputs) for operator intervention. This provides added cabling and power supply diagnostics
for non-IT or engineering trained personnel.
2. Serial configuration port for managed switches: A serial configuration port allows the
IP addressing of managed switches or the confirmation of an IP address by plant personnel
(using Hyper Terminal with a laptop) without special software, training, or network access.
3. Automatic re-addressing of replacement devices with DHCP Option 82: DHCP Option
82 allows dynamic IP address assignment for the attached nodes to either be fixed, based on
the port they are plugged into (instead of their MAC_ID), or centrally managed (typically
based in the IT Department) in a server that contains the master IP address list. This function
eliminates the need to manually assign the same IP address to a replacement device’s new
MAC address.
4. Complete web access to all switch parameters: If the EtherNet/IP system is to be
primarily maintained by plant and control engineering personnel, there is a greater need to
have all switch configuration parameters accessible from standard laptop browsers.
Parameters that can only be accessed via SNMP network management software require the
purchase of network management software or reliance on IT Department tools and personnel.
If the control network is to be primarily maintained by IT personnel, this is not as great a
requirement.
5. Port mirroring: This function allows traffic from any port on a switch to be duplicated on a
spare port for advanced network diagnostic monitoring and troubleshooting. Port mirroring is
the function that provides compatibility with IT-level network troubleshooting tools.
6. Physical storage/retrieval of switch configuration: As an alternative to network-based
auto-addressing and auto-reconfiguration, memory cards or modules may be used to store a
switch’s configuration. If replacement of a switch becomes necessary, plant personnel can
remove the card or module from the previous switch, insert it into the new switch, and have