From: Marc Lavine (firstname.lastname@example.org)
Some versions of our sFlow agent code could improperly report the sampled packet
sizes as 144 bytes. This seems to match up with the numbers you're observing
(215.2 KB * 1024 / 1536 packets = ~144 bytes/packet). I think you'll need to
get an updated version of the router software to correct this problem. Sorry
for the glitch...
Foundry Networks, Inc.
> I am trying to use nTop 2.1.56 to monitor the traffic over my network using
> I use nTop has a collector for the S-Flow packets sent by my router.
> Packet sampling rate is 1 per 512 packets.
> The nTop SFlow plugin should be correctly configured as the sFlow collector.
> But I get strange results:
> For instance, I tried to send a 1 GB file at 1 MB/s on the network. nTop
> reports the following :
> Stats / Throughput : Current / Peak ~ 2 Kbps
> Total Data Sent : 1536 packets = 215.2 KB
> I don't understand those results, I was expecting to have:
> total_size_sent * sampling_rate = total_size_received_by_ntop
> but actually we have here total_size_sent * sampling_rate = 2048 KB
> which has nothing to do with total_size_received_by_ntop...
> But, if we assume an IP packet size is about 1448 bytes, then we have:
> packets_sent = 1 GB / 1448 bytes
> and I observed indeed:
> packet_sent * sampling_rate ~ packets_received_by_ntop
> So, why the size (and the speed) is wrong ?
> Does anyone here has managed to use ntop with sflow correctly ?
> Thanks for your help...
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