Cisco switch and SNMP Traffic 64bit sensor

hello, what exactly do you want to know.

when the SNMP request is sent to the device it returns a value, if you have two values, the difference between the values is the transferred volume.

The volume divided by the scanning interval is the speed.

Hello, Thank you for your response.

First of all I'd love to know the difference between volume and speed.

Additionally, I want to know whether the return value from the equipment Is the exact speed at the sampling moment or an average value of minute or thirty seconds.

Thank you, Yaron

Hello. I'd love to know the difference between speed and a volume in addition to what is the information that is returned from the monitored switch. Regards, Yaron

The question is already answered. We do not see the difficulties here.

Dear Aurelio,

As I understand from the above answer the PRTG speed info is basically an average. According to the below information there is still a difference - can you explain it?

Time Traffic Total (volume) Traffic Total (speed)

12:25 281 MByte 39 Mbit/s 12:24 278 MByte 39 Mbit/s 12:23 282 MByte 39 Mbit/s 12:22 277 MByte 39 Mbit/s 12:21 246 MByte 34 Mbit/s

Total volume=281 MByte then during this minute speed should be 281*8/60 ~ 37.46 Mbps, but the table suggests it 39 Mbps. same issue with 277 MByte -> 36.9 Mbps and not 39 for sure.

I think that an interesting question is what the monitored switch returns for the SNMP request (for example CISCO). Is the switch making an average by itself over a certain timeframe and returning its average value? Alternatively, is it returning the exact momentary value once the SNMP request arrives?

Thanks for your

Dear Aurelio, All,

Can you clarify this issue of volume and speed - how exactly the speed is calculated ? Thanks,

Rotem

This issue was raised again by our team. can you please refer to this issue and clarify?

According to my check on our enviroment the volume MByte and the Speed Mbps are not matching this explanation. Quote: "...if you have two values, the difference between the values is the transferred volume. The volume divided by the scanning interval is the speed."

Note that our scanning interval is every minute. On the below table, taken from PRTG- 82,304 Mbytes where transferred during one minute, therefore 82,304*8= 658,432 Mbits where transferred - so 658,432/60 =10,973 Mbps. This is much lower than the PRTG speed presented for the same sample 11,507 Mbps.

date	               time	              volume	        speed
10/20/2014	12:49:00		82,304		11,507
10/20/2014	12:48:00		80,725		11,286
10/20/2014	12:47:00		81,467		11,390

Thanks,

Rotem

Volume calculations are 1024 based. Speed calculations are 1000 based.

82304 Mbyte * (1024*1024) = 86301999104 Byte 86301999104 Byte * 8 = 690415992832 Bit 690415992832 Bit / 60s = 11506933213 Bit / Second 11506933213 bps / (1000*1000) = 11507 mbps