Knowledge Drop for when to use a managed or an unmanaged switch

Dan French, with Anixter's Industrial Communication and Control marketing team, talks a about when to use a managed or an unmanaged switch in an industrial Ethernet network.





Connect with Dan on

Managed Switches Video Transcript

Hi, I’m Dan with the Anixter Industrial Communication and Control marketing team. I want to talk a little bit about when you want to use a managed or an unmanaged switch in an industrial Ethernet network.


First we’ll talk about the differences between an unmanaged switch and a managed switch, and then we’ll cover when it makes sense to use each type of switch. Unmanaged switches simply allow Ethernet devices to communicate with one another by providing a connection to the network. Unmanaged switches are truly plug and play devices, meaning you simply have to plug them in for them to work. This simplicity does come at a cost of higher functionality.


Managed switches, out of the box, offer all of the functionality of an unmanaged switch; however, they also offer plenty of other features that make it possible to manage and troubleshoot your network. In the next part of this video, we’ll get into the most common of those features to be utilized in the industrial space.


Managed switches use a protocol called Simple Network Management Protocol or SNMP. SNMP is used to relay network configuration data to network engineers and allows them to set configuration parameters remotely. SNMP reduces troubleshooting time and increases uptime.


Data prioritization is also important in all networks, especially industrial networks. This can be done on a managed switch by setting quality of service. Another way of achieving this is by segmenting your network with the use of virtual local area networks, or V-LANS. These features are important for time-sensitive control data, but also for nonindustrial applications like Voice over IP.


There are also more advanced timing technologies available such as IEEE 1588 that allows even more deterministic transfer of data. Controlling multicast traffic would fall along that same train of thought. This can be done using the Internet Group Management Protocol, or IGMP. This protocol ensures that multicast traffic reaches its intended destination or destinations while not needlessly flooding that traffic onto the rest of the network.


Unmanaged switches do not support IGMP and treat multicast traffic in the same fashion as broadcast traffic, which can overwhelm a network when uncontrolled and lead to broadcast storms. This feature is particularly important on industrial networks because the protocol EtherNet/IP relies heavily on multicast traffic.

 

Uptime is extremely important in industrial systems, while their environment is often very harsh. If a link or device fails on the network, it is imperative that the remainder of the network remains functional. Managed Ethernet switches have many options for redundancy incase of failure. The two most common redundant configurations are Rapid Spanning Tree Protocol (RSTP) and ring topologies.

 

All of the features of managed switches do come at additional costs, so it is important to know when to select a hardened managed switch or when an unmanaged switch can be used. Unmanaged switches are mostly used to connect edge devices on network spurs or on a small stand-alone network with only a few components.

 

Managed switches should be used on any network backbone switch so that segments of network traffic can be monitored and controlled. Additionally, any device that would be considered critical to your network should be connected via a managed switch. Finally, switches being implemented in an Ethernet IP network should be managed because of their ability to handle multicast traffic.

 

That’s it for this video. I hope you’ve learned something new today. If you have any further questions, please contact your Anixter representative.