PTP820G Unit Redundancy Issues


As a function of numerous single point of failure and DOA issues I realized with PTP820Gs, Cambium provided extra PTP820Gs, Electrical Ethernet Protection Splitter cables, TDM Protection Splitter cables, and Management Protection Splitter cables in order to facilitate configuration of Unit Redunancy.

Following the instructions contained in the manual, I attempted to configure Unit Redundancy but have hit a brick wall.  Both PTP820Gs are the same hardware vintage and are both running 9.7.  Both units have been factory defaulted.  When the RJ45 plugs of the Management Protection Splitter cable are plugged into the Management interfaces AND the end of the cable which would terminate to a Management PC is left UNTERMINATED, the LEDs on the IDUs indicate a physical connection to one another, however, as soon as I terminate the cable to a Management station, e.g. a PC, the connection between the IDUs fail and the LEDs go through a cycle implicative of an attempt to negotiate physical connections between one another AND the Management terminal, but the connection never happens.

The PC never realizes a physical connection, either.  I’ve tried changing speed and duplex settings on the NIC, I’ve tried multiple PCs, I’ve tried a different Splitter cable, I’ve tried using an Ethernet switch instead of a PC, I’ve tried using a crossover cable, all to no avail.

Cambium is, at this point, at a loss as to why this is not working.  They assert they performed this exact same configuration in their lab a few weeks ago and did not experience any issues.  I’m currently in a holding pattern waiting to hear back from them with direction.

I should also mention that I’ve enabled Management Interface 2.  

I am am to a point where not being able to form a simple physical connection between the IDUs and my PC prevents me from logging into one of the units through the Protection cable, per the manual, to enable Unit Redundancy.  So, I am experiencing Layer 1 issues before even configuring a single parameter.

Any thoughts?

Hi Matt,

I'm glad we were able to figure this out yesterday.  Let me know if you have any other questions.  For those that might stop by looking for the answer, the missing step was that we had to enable redundancy on both units before connecting the Y cable.

So the steps for enabling unit redundancy on the PTP 820 G are:

  1. After an IP address is assigned to each unit, connect to one of the units via standard straight Ethernet cable and enable unit redundancy
  2. Proceed and disconnect the MNG cable from the first unit, and connect it to the second unit and enable the unit redundancy.
  3. Disconnect the straight Ethernet cable from the second unit
  4. Connect C000082L155A cable to both units
  5. Connect the socket end of the Y cable to your laptop or switch using a standard Ethernet cable


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Thank you for your assistance.  Our configuration efforts went well today.  I will provide you with an update on our email thread.

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