We have identified an issue with high latency transfer rates in some cases.
Turns out our traffic was solely exhausting upstream router fabric, but even increasing fabric capacity did not solve this, or even moving some of our links to an other linecard.
We will move those links to a bigger router and closer to next hop fiber links, with increased capacity sometime Monday after 16:00.
This should solve the issues with some high latency transfers. Essentially a few packets here and there drops, causing the TCP window sizes (essentially how fast to transfer) to decrease significantly. This also causes fluctuation in transfer rates.
Not all higher latency transfer rates are affected, but many are.
We remained peak at ~70-75% of maximum capacity. The router also seemingly, on paper, had more than enough capacity but that particular version has essentially a "gotcha" with fabric configurations, but even distributing the load more did not solve this. It is not every day you exhaust chassis router fabric :)
We have also noticed more and more ISPs are throttling FTP traffic. If you are having FTP speed issues, please move to SFTP. Also ensure you have multiple threads if you are not achieving decent throughput.
Friday, February 14, 2020