Unusual peaking of ISP

[Dyop_Geop]

Unusual peaking of ISP

Hi fellow fortinet engineers,

I've been encountering this issue for a few days now, randomly.

Please see screenshot of our monitoring system. PRTG. 

We have 4 ISPs and the 3 ISPs went down and unusually boosted up in terms of bandwidth. I mean ridiculously peaked. All three of them. simultaneously.

All of our ISPs are at 30mbps only.

My question is, have any of you fellow engineers encountered this issue? What do you think is the cause?  Is there a way for our fortigate to show what causes this?  Hope someone could answer.

Thanks everyone.

[Jeff_FTNT]

From timestamp  (11:40), it look FGT is doing AV/IPS signature update.You may use small Fortigate with UTM enable on policy.Check the FortiGate Event to see what happen on that time, thanks.

[Dave_Hall]

If your ISP(s) employ burstable bandwidth then that could be what you are seeing.  But, I'm more incline to think it's a "glitch" or how the buffering of the graphing data is sent to the monitoring software; we see this ourselves with our own monitoring tools (mainly Zenoss) when a site goes down briefly or we have a temp problem with our backhaul or server connection.  I would be more concerned about your 3 x ISP connections going down at once (unless all connections are with the same ISP).