Frame loss on modulation change

Dear All

I am running 2x B5c PTP link in our lab (RF cable & attenuators) and experience some frame losses when modulation changes.
Another issue we saw, the link is very sensitive in MCS9 @40MHz , even in the lab condition (RSSI ~48dBm, SNR 35dB).

I would appreciate your help


I am running 2 X 40MHz on a B5 link at 2.7KM distance, and my MCS is rock solid 9 with similar value to what you have.
RSSI at -45dBm and SNR at 35dB.

Here is what my MCS looks like for one week.

Reading more posts in the forum I am not sure the problem is in the AIR rather than Ethernet port.
We spent too much time already but we would like to find the reasons before giving up.

We changed AP to Auto mode (Freq , TxP, CBW, Ratio), but continue to get frame losses even with low throughput (50Mbps generated with JDSU)

What are we missing ? the setup is very simple , RF Cable & Attenuators.


Here is what I see on the switch port that B5 is connected to:

This is on a Cisco SG-200 switch.

Here is a snapshot of one side:
See the PER scale.

I am very pleased with my results as all looks very good here.

I have seen other users reporting compatibility issues with some switches. Should be fixed in firmware version 1.4.4.

I have my AP set to “MANUAL MASTER” under network interface. Station is set to “MANUAL SLAVE”.
Don’t know if this did anything since I did not notice any problems before doing this.

Here is the router in the opposite end of the link.
B5 connected to WAN1 port.


I am having few problems

  1. Ethernet Port - failed to sync at 1Gbps, only at 100Mbps (we tried everything !!! , changing PoE, connecting it to switch/pc/JDSU…) BIG ISSUE!!!
  2. Radio - Even in controlled lab environment (AP —> ATT–>CABLE<—ATT<–STATION) it seems that there is different between chain around 15dB. (it starts equel but than started a drift till it reach 10dB difference )
  3. Dual Carrier - 4 chains attempt to transmit but only 2/3 chained receive (same for both unit)



I wonder if your Radio issue is related to automatic TX power adjustment.
It is discussed in this post:

Our most critical issue is Ethernet port (L1 sync loss reported via JDSU)
second problem, high PER & low performance in controlled lab environment

Changing roles between units (AP–> STATION , STATION -->AP) solved some performance issue (very strange !!!)

Question about MAC Tx/Rx counter in dashboard- from our test it is far from accurate, we are trying to transmit traffic according to this value while the link can handle lower throughput