Am I calculating total throughput correctly on my LTM?

I am attempting to calculate the total throughput on my F5-Big-LTM-3600-4G-R with PRTG via SNMP queries and my own calculations.

 

I have used the "Collecting data on throughput" section in this post as a reference: http://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip9_0sys/9_0_xSystemMgmtGuide-12-1.html The part of this article that I do not understand is what values in bytes the OIDs they are using are actually providing, and what the "time" value would be that they are suggesting to divide by.

 

 

For reference, here are the OIDs that I am using and their names and descriptions:

 

1.3.6.1.4.1.3375.2.1.1.2.1.74.0 - F5-BIGIP-SYSTEM-MIB|sys global stat|sys stat client bytes in1m "The average number of bytes received by the system from client-side in the last one minute."

 

1.3.6.1.4.1.3375.2.1.1.2.1.76.0 - F5-BIGIP-SYSTEM-MIB|sys global stat|sys stat client bytes out1m "The average number of bytes sent to client-side from the system in the last one minute."

 

1.3.6.1.4.1.3375.2.1.1.2.1.81.0 - F5-BIGIP-SYSTEM-MIB|sys global stat|sys stat server bytes in1m "The average number of bytes received by the system from server-side in the last one minute."

 

1.3.6.1.4.1.3375.2.1.1.2.1.83.0 - F5-BIGIP-SYSTEM-MIB|sys global stat|sys stat server bytes out1m "The average number of bytes sent to server-side from the system in the last one minute."

 

I am doing the following via custom SNMP monitors in PRTG:

 

SNMP get of: 1.3.6.1.4.1.3375.2.1.1.2.1.74.0 and multiply that value (which is in bytes) by 8 (to give me bits) then divide the resultant value by 1024 which results in "Client Kbps In"

 

SNMP get of: 1.3.6.1.4.1.3375.2.1.1.2.1.76.0 and multiply that value (which is in bytes) by 8 (to give me bits) then divide the resultant value by 1024 which results in "Client Kbps Out"

 

SNMP get of: 1.3.6.1.4.1.3375.2.1.1.2.1.81.0 and multiply that value (which is in bytes) by 8 (to give me bits) then divide the resultant value by 1024 which results in "Server Kbps In"

 

SNMP get of: 1.3.6.1.4.1.3375.2.1.1.2.1.83.0 and multiply that value (which is in bytes) by 8 (to give me bits) then divide the resultant value by 1024 which results in "Server Kbps Out"

 

Then, I add all 4 of these values together and divide the sum by 1024 to get Mbps.

 

However, the issue I am seeing is that the "Total Throughput" measurement on the F5 dashboard is significantly lower than my sum calculated in PRTG of the four measurements shown above. For instance, the dashboard is currently showing 95Mbps and my PRTG monitor says 150Mbps.

 

See the respective graphs for the past 24 hours:

 

F5 dashboard:

 

My calculated PRTG dashboard:

 

What am I missing here?