Terrible Download Speeds on Fortigate 90D

Forum|Forum|10 years ago
January 29, 2016
1 reply
15292 views

Hi everyone. Thanks in advance for any help you can provide.

We have a Fortigate 90D and a 50Mbps (up and down) connection at our office. The speed test at http://speedof.me/ came up at approx 37Mbps up and down, which is fine, as I ran the test in the middle of the workday. HOWEVER, downloading files and other web activity can be painfully slow, sometimes as slow as 100KBps (!). I look at the bandwidth graph on the 90D and i see nothing to suggest that something is hogging bandwidth. The CPU is hovering around 10%.

Sometimes, downloads are fine. I downloaded a VMWare iso at 2.4MBps. Other times, the downloads are awful. I tried downloading a Windows Service Pack and it went at about 200KBps.

Any thoughts? I will provide whatever details I can.

ede_pfau

SuperUser

hi,

one reason for slow speeds on a fast line can be a mismatch of the MTU. If IP packets are larger than the MTU they need to be fragmented which can cause latency.

Your ISP should give you infos on the kind of connection and if there is a smaller MTU used than 1518 bytes.

kommgroupAuthor

New Member

thanks! i will ask.

Dave_Hall

New Member

If you have any UTM features (mainly virus scanning) enabled on the policy covering the effected traffic, keep in mind that the fgt will try to buffer the entire file to it's max buffer size limit (usually 10 MB) before "releasing" it or dropping it (based on what is the default action). (At least in proxy mode.) This virus scanning does "slow down" the transfer rate; Fortinet use to publish actual "Antivirus Throughput" data on their datasheets, but appears to be "removed" from later models and/or balled into their NGFW throughput data.

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