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Network Switch Incompatibilities

Introduction

Networked Robotics NTMS network hardware has trouble in some cases with some, newer, managed network switches. This seems to be the case with Hewlett Packard's HP Procurve® switches.  This document describes situations where this may occur, and describes a solution.

Symptoms and Why the Problem Occurs

The most common manifestation of the problem is that data is initially collected but then stops over time.  Power cycling the NTMS solves the problem, but only for a limited time that might be several minutes or several days.  The "ping" and "Telnet" commands are not successful until the unit is power cycled.

The Networked Robotics NTMS device was developed in 2004, and uses the Realtek 8019AS chip to manage network communications.  This 10 Mbit network controller has since shown some incompatibilities with newer switches.

Avoiding Incompatibilities

Select a switch with advertised 10 Mbit support.  The switch should support 10/100 or 10/100/Gigabit performance and should be autosensing. The RTL 8019 is a full duplex controller. 

Solution

If you have an HP Procurve or other incompatible switch the best solution is to put an intermediate, unmanaged 10 Megabit or 10/100 switch between the incompatible switch and the NTMS hardware.  (A 10 Mbit hub can also be used but do not use hubs of higher speeds.)

Your  network closet is comprised of a patch panel and switch as shown below.  The switch feeds the wall jacks in each room to which your computer is connected to the internet.

Add a second switch, a 10/100 switch in your network closet in between the incompatible switch and the NTMS units such that the NTMSs are plugged into the unmanaged switch.  Power cycle the Networked Robotics NTMS units.  When configured in the Tempurity Server data collection should occur constantly.

Conclusion

If data collection is interrupted, consider the possibility of a switch incompatibility.  Put an unmanaged 10/100 switch in betweeen the incompatible switch and your NTMS units.