As per Damien's response - TCP throughput (single stream) will depend on window size. Default on Microsoft Windows is 64KB from memory.
Latency dramatically impacts the throughput. Based on a 250Mb/s link the below is likely to USA West Coast (with latency of 169ms which just happened to be a random host I picked - I am in Melbourne) Bandwidth / latency (250 Mbit/sec, 169.0 ms) required tcp buffer to reach 250 Mbps with RTT of 169.0 ms >= 5157.5 KByte maximum throughput with a TCP window of 64 KByte and RTT of 169.0 ms <= 3.10 Mbit/sec. You either need to adjust window / buffer size or use multiple streams. Glenn ________________________________ From: AusNOG <[email protected]> on behalf of Damien Gardner Jnr <[email protected]> Sent: Friday, 13 October 2017 7:04:08 PM To: Dino Sosic Cc: [email protected] Subject: Re: [AusNOG] Speeds to international - acceptable minimum Depends on whether you've tuned the TCP stack on the machine you're testing from.. With default window sizes etc, I'd expect maybe 10-20mbps per stream from the US, less from Europe? With nice large window sizes and receive buffers, I'd be expecting 100-150mbps per stream, provided the server on the other end isn't limiting window sizes to something stupidly low? (Have had that issue a few times with SaaS providers in the US.. Usually an email to their helpdesk with some pcaps, and an explanation of how window sizes work, and how they need to tune their servers, will result in a huge jump in performance) A short look with tcpdump, ethereal, etc should tell you whether it's a window size issue, or something further upstream. If you can, adding an adjust-mss rule on your router to say drop your negotiated mss on outbound connections to say 1400, may make a (large) difference if your provider is using a GRE-based DDoS mitigation platform in the US, and they're doing transparent packet fragmentation, rather than just sending back frag-needed packets. On 12 October 2017 at 18:22, Dino Sosic <[email protected]<mailto:[email protected]>> wrote: Hi, Out of curiosity, if you get a 250 mbps circuit from an ISP (IP transit service) and all is fine within ANZ but as soon as you go international speed tests show 2/2 mbps, FTP transfers show 7/8 mbps, would that be acceptable? (Same towards multiple US, Europe and Asia destinations) What is the minimum you would deem acceptable to international destinations? Cheers Dino Confidentiality and Privilege Notice This document is intended solely for the named addressee. The information contained in the pages is confidential and contains legally privileged information. If you are not the addressee indicated in this message or responsible for delivery of the message to such person, you may not copy or deliver this message to anyone, and you should destroy this message and kindly notify the sender by reply email. Confidentiality and legal privilege are not waived or lost by reason of mistaken delivery to you. _______________________________________________ AusNOG mailing list [email protected]<mailto:[email protected]> http://lists.ausnog.net/mailman/listinfo/ausnog -- Damien Gardner Jnr VK2TDG. Dip EE. GradIEAust [email protected]<mailto:[email protected]> - http://www.rendrag.net/ -- We rode on the winds of the rising storm, We ran to the sounds of thunder. We danced among the lightning bolts, and tore the world asunder ________________________________ Message protected by MailGuard: e-mail anti-virus, anti-spam and content filtering. http://www.mailguard.com.au Report this message as spam<https://console.mailguard.com.au/ras/1RRExreQzL/7mQJFYUEJNBOfZ0n7wWQjB/1.2>
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