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I see what you mean on the Aggregate graphs on the MICE Looking Glass.
http://micelg.usinternet.com/cacti/graph.php?action=view&local_graph_id=2625&rra_id=all
It could be a real member port doing something--but those are ~100 Gbps spikes.
What I also notice is that each spike is followed by a dip of
roughly the same magnitude. This makes me think of sampling
jitter (or artifacts, or noise)
It's hard to describe but port counters don't update every second, sometimes it's every 30 seconds. Then Cacti comes along every approx 5 minutes (300 seconds) to poll the counters. The slight mismatch in timing means that Cacti usually gets 10 counter updates per 300 seconds--but every hour it gets 11 on one interval, and 9 on the next.
Overall, the graph is accurate, but it shows this 5% noise every
hour.
This is guesswork in the case of MICE, but I've seen this in
other networks,
Cheers,
Jonathan
Jonathan Stewart Network Engineer LES.NET - AS18451 Desk: 1-204-666-6191 Mobile: 1-204-990-2120 130 Portage Avenue E Winnipeg, MB R3C 0A1 CANADA