The Hidden Cost of Using Unmanaged Switches

Posted by Walter Brumbalow
The 21st century has produced many changes on the plant floor most significantly the introduction of Ethernet networks utilized in control systems. Control system networks form the central nervous system of the manufacturing process allowing associated equipment to communicate in a coordinated and predictable manner. When control system networks are disrupted, the corresponding manufacturing process suffers via plummeting efficiencies and lost production. For this reason, it is crucial that network issues are diagnosed quickly and, if possible, prevented from occurring altogether.

Early in industrial Ethernet adoption, unmanaged switches were commonly utilized mainly for the price savings relative to a managed alternative. To reduce costs, switch manufacturers design unmanaged switches with no feature sets or means of configuration, they are simply plug-n-play devices. Monitoring of vital statistics and diagnostics are also not available.

On the other hand, managed switches implement features allowing for the control and management of frames passing through them. Common management features include VLAN (Virtual Local Area Network), IGMP (Internet Group Management Protocol) Snooping and Querier and network redundancy protocols such as RSTP (Rapid Spanning Tree). These features can be implemented to customize a switches' configuration for specific application requirements vastly improving the availability, stability and efficiency for a given network.

Most managed switches also implement SNMP (Simple Network Management Protocol) for remote monitoring and control. Utilizing SNMP with a NMS (Network Management System), such as Hirschmann Industrial HiVision or Moxa MXView, gives maintenance and administrative staff real-time network status and health of their network. This visibility drastically reduces times associated with troubleshooting and provides for preempting problems before they negatively impact the process.

The initial cost savings of an unmanaged switch over a managed alternative quickly disappears when the increased costs associated with extended troubleshooting times are factored in. Networks implementing unmanaged switches are effectively flying blind leaving maintenance and administrative staff few options when diagnosing issues and no ability to proactively head off problems that would otherwise threaten the stability of the process.

In recent years the price difference between managed and unmanaged switches has closed considerably making managed switches financially justifiable in a wider array of applications. For this reason, INS recommends utilizing managed switches for new applications and upgrading existing unmanaged switches where applicable.

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