B5c and B24 SNMP Monitoring

Network Management
#1

Hi All,

Looking for some guidance on monitoring via SNMP on our B5c’s and B24 back hauls. Currently I have a lot of data being pulled into my Zabbix sever via SNMP and looking to get some confirmation on a few values.

I was following this: http://backhaul.help.mimosa.co/snmp-oid-reference

Examples of what i am able to get in is the Phy TX/RX values, TDMA details(Windows, Traffic Split, Mode) I am wanting to use these Values to calculate the MAC TX/RX values using the formula details here http://backhaul.help.mimosa.co/backhaul-faq-what-is-mac-throughput

So i have B5c back haul, where I have this working by using getting all the Physical TX/RX stream values, adding them together, I have the Traffic split mode, which is 75/25, and the Window which is 8ms, Creating a calculated item in Zabbix i am able to calculate a very close MAC TX/RX that we can monitor now.
Example:
MAC Tx Throughput = (Total Tx PHY rate) * 0.75 * 0.90
MAC Rx Throughput = (Total Rx PHY rate) * 0.25 * 0.90

My issues is coming from the values i get for Traffic Split.
When i pull the Traffic rate from a B24 running in auto mode i get the value “1”, which is the same value of the B24 running 75/25 from the AP side, and 2 from the Station side which is “25” and the MAC is calculated but is wrong in compared to the Web UI

Do you guys know what I should be looking for here, like if it’s in Auto Mode what would a traffic split value of 1 or 2 equal? Is there another OID that maybe I am missing?

I’m going to keep looking into things, Everything else I’ve pulled into Zabbix via SNMP has been really useful, we are just really looking to get the MAC TX/RX in it as well.

Thanks in advance.

#2

I have a B24, could you reference me the specific OUIs you are looking up so I can double check what I get?

#3

Yea For sure,

1.3.6.1.4.1.43356.2.1.2.4.3.0 Traffic Split
1.3.6.1.4.1.43356.2.1.2.4.4.0 Traffic Window

AP side on a 75/25 i get a 1 from the Traffic Split
and a 4 from traffic window
SM Side 25/75 i get a 2 from the Traffic Split
and a 4 from traffic window

Which is good. I Gathered 1 meant 75 and 2 meant 25.

On another link that is set to auto:

AP side on a auto i get a 1 from the Traffic Split
and a 4 from traffic window
SM Side i get a 2 from the Traffic Split
and a 4 from traffic window

Which isn’t good, because its the same results of a 75/25, but the current MAC is 480/360 which isn’t a 75/25 split.

Hopefully that makes sense?

#4

Could it be that the MAC is being impacted by a low SNR? That could drop your split throughput unequally.

#5

Looking at about 24-27 SNR on the RX AP Side

in the formula, they don’t take in account for the SNR, but maybe there is an issue there as well?

#6

ya, 24 dB SNR will start dropping your MCS (Which is a factor in your overall throughput)

http://backhaul.help.mimosa.co/backhaul-faq-snr-mcs

Also:

http://backhaul.help.mimosa.co/backhaul-faq-sensitivity-for-each-mcs-index

You will significantly lower traffic levels and get a lot of modulation changes with an SNR of what you are seeing.

#7

Hi, just jumping in, Jon and I work together, just a few other observations. We were advised to try lowering the power on the link by Mimosa support, right now we are at -3 I think for power. Overall SNR in the cloud data is 32-34.5. However the link will not hold at 2x80, gets flaky. But is rock solid at 2x40 (although we have the differing MAC numbers between RX and TX). So not sure, something just seems strange on this link which is why Jon’s trying to mine more info via SNMP. We have others out there at 2x80 with no problems.

#8

After some tweaking with pulling SNMP values into our Zabbix I Managed to get some data flowing into it.

From looking at the MAC Values in the web UI and pulling the physical values i was able to calculate them accurately as a 75/25 traffic split on a 4ms tdma window(b24 is set to auto mode at the moment). My calculated MAC values now match the web UI.

Here is some Other SNMP data i am pulling in the hope to figure out what causing this link to have issues, this is what the past 12 hours of our link looked like on a b24:

  • Chain 1
    • SNR
      • AVG: 28.79
      • MIN/MAX: 24.8/31.6
        • Diff: 6.8
    • Noise
      • AVG: -85.92
      • MIN/MAX: -86.3/-82.9
    • Rx Power
      • AVG: -57.12
      • MIN/MAX: -60.4/-54.5
  • Chain 2
    • SNR
      • AVG: 29.97
      • MIN/MAX: 24.7/32.9
        • Diff: 8.2
    • Noise
      • AVG: 85.92
      • MIN/MAX: -86.3/-82.9
    • Rx Power
      • AVG: -56.66
      • MIN/MAX: -59.5/-53.2
  • Chain 3
    • SNR
      • AVG: 30.31
      • MIN/MAX: 26.2/32.5
        • Diff: 6.3
    • Noise
      • AVG: -86.82
      • MIN/MAX: -87.1/-84.9
    • Rx Power
      • AVG:-56.51
      • MIN/MAX: -60.2/-54.4
  • Chain 4
    • SNR
      • AVG: 29.74
      • MIN/MAX: 26.7/32
        • Diff: 5.3
    • Noise
      • AVG: -86.82
      • MIN/MAX: -87.1/-84.9
    • Rx Power
      • AVG: -57.08
      • MIN/MAX: -59.5/-54.9

It looks like our 4th chain does drop out time to time, not sure if this is by design.

We have two 2x80 links located with 2km of each other working solid, but can’t get this link to do 2x80 when it off by it’s self. (30km away from the nearest known 24ghz)

The Physical TX and RX rates do drop when the SNR drops (This is in 2x40)

SNR
image
Physical TX
image
Physical RX
image

From the looks of the spectrum analyzer there is no interference for the link.
We might be able to decrease the TX power some more, but comparing to our other links it just seems to not be working when it should.

any idea or suggestions would be great.
If there is any particular data anyone would need to help let me know and i can see if we have it.

#9

Could there be some sort of moving obstruction? that is quite a lot of movement for a signal in such a short amount of time.

TBH, I would suspect the alignment. Maybe you might want to try checking it out and see if maybe something is off kilter. If your signal is dropping below the SNR requirements for holding the higher MCS that would explain the issue.

You could turn up the TX power, but it seems to me like you have more of an issue with signal fluctuation then particular antenna issues. At the moment, I could be wrong and you just have a bum radio. Either way, if you do go to check the alignment, I would leave the power as low as it can go so that you avoid getting stuck on a side lobe a little bit less easily.