Cluster PMP450i AP and CMM4 Gigabit Considerations

Hello Community,

I am trying to figure out what is the bes installation/cabling of a cluster with Gigabit support using PMP450i and Surge suppressors.

In the cluster I have 3 AP PMP450i Connectorized, their ethernet interfaces are 100/1000 FD.  If I using a CMM4 for SYNC, how suppose I have to do the cabling of system to get Gigabit support of the 3 AP. I have to power up the AP with the PIDU use Gigabit Surge Suppressor but I lost the SYNC of the cluster.  Some have a right diagram to do this or I have to lost the Gigabit capacity in the cluster.  Note: I cannot use the new CMM5, I have to use the CMM4.

Thank you for your comments and help.

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The CMM4 interface is only Fast Ethernet i.e 100Mbps, so even of the radio supports 1000 Gbps the negotiation between the radio and the CMM4.

I believe CMM5 is the solution for you, it supports Gigabit interface.

I will check if there are any alternates apart from the CMM5 and will reply back.


Sanjay Kumar

As Sanjay notes, using the CMM4, the radio will always negotiate to 100BaseT (the CMM4 is not capable of providing Gigabit links to the radios. 

That said, however, with 450i, it is pretty rare to be able to support greater than 100 Mbps in a single direction in reality.  As an example, using 20 MHz channels, the maximum aggregate throughput is ~125 Mbps in 8x mode, and ~95 Mbps in 6x.  In the field, it's pretty rare that all radios are operating in the highest modulation mode.

When you factor in that typically 75% of the frame is downlink, you'll see at most 75-80 Mbps in a single direction, so the 100 Mbps limit of the 100BaseT connection will not be a limiting factor.

If you believe otherwise, please post additional sector information and we can discuss alternative options.