Comments on: How to Calculate TCP throughput for long distance WAN links http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-distance-links/ Studies in Data Center Networking, Virtualization, Computing Mon, 06 Feb 2012 01:52:15 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Guru http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-distance-links/comment-page-2/#comment-8623 Guru Fri, 03 Feb 2012 13:39:55 +0000 http://www.bradhedlund.com/?p=74#comment-8623 Nice post.. referred it in my post http://www.consultguru.me/post/2012/02/02/SQL-Server-Replication-Project-–-2-(Network).aspx Guru Nice post.. referred it in my post

http://www.consultguru.me/post/2012/02/02/SQL-Server-Replication-Project-–-2-(Network).aspx

Guru

]]> By: Georgie http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-distance-links/comment-page-2/#comment-8374 Georgie Wed, 30 Nov 2011 13:45:39 +0000 http://www.bradhedlund.com/?p=74#comment-8374 " unless your TCP/IP stack on the server employs a TCP enhancement called “selective acknowledgements”, which most do not" In my experience any recent Linux 2.4/2.6 kernel and any modern Window$ system have SACK enabled by default in the kernel. ” unless your TCP/IP stack on the server employs a TCP enhancement called “selective acknowledgements”, which most do not”

In my experience any recent Linux 2.4/2.6 kernel and any modern Window$ system have SACK enabled by default in the kernel.

]]> By: uday http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-distance-links/comment-page-2/#comment-8153 uday Wed, 21 Sep 2011 17:38:53 +0000 http://www.bradhedlund.com/?p=74#comment-8153 how to find the throughput,end to end delay,delivery ratio for the protocols using mcbr application as it is a single host application.. what all properties has to be set for that in nodes,sunet and mcbr and file statistics... of scenario in qualnet 5.0 environment.. how to find the throughput,end to end delay,delivery ratio for the protocols using mcbr application as it is a single host application..
what all properties has to be set for that in nodes,sunet and mcbr and file statistics…
of scenario in qualnet 5.0 environment..

]]> By: NBN fibre in small towns http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-distance-links/comment-page-2/#comment-8055 NBN fibre in small towns Sat, 20 Aug 2011 02:19:48 +0000 http://www.bradhedlund.com/?p=74#comment-8055 [...] thus the further increase of latency. Alright then Comrade, I'll humour you for a moment. Using this article as a base I will be doing some calculations. Next I will use Tranquillity as my server, which is [...] [...] thus the further increase of latency. Alright then Comrade, I’ll humour you for a moment. Using this article as a base I will be doing some calculations. Next I will use Tranquillity as my server, which is [...]

]]> By: John Tkaczewski http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-distance-links/comment-page-2/#comment-7837 John Tkaczewski Thu, 04 Aug 2011 01:21:23 +0000 http://www.bradhedlund.com/?p=74#comment-7837 It is worth to mention that besides WAAS, there is a number of other commercial software vendors that provide accelerated file transfer software. At FileCatalyst, we use a UDP based protocol to send data at the maximum available link speed. Unlike other UDP based file transfer protocols, we use an efficient algorithm to keep track of lost pockets and we re-transmit only the missing data. With much fewer acknowledgments than any other TCP based protocol, the file transfer speed is not affected by the latency. And the speed loss is linear to the pocket loss (Which is impossible with large Window Sizes) We also use our own built-in congestion control that is immune to latency and takes into the account the average latency of the link before slowing down. We have an on-line calculator on our web site that provides a comparative of TCP over our UDP protocol. http://www.filecatalyst.com/web_demos/comparison_tool.html I recognize that this is plug for a commercial product however this article explains exactly the same problem that we have been trying to fix for the last 5 years. It is worth to mention that besides WAAS, there is a number of other commercial software vendors that provide accelerated file transfer software. At FileCatalyst, we use a UDP based protocol to send data at the maximum available link speed. Unlike other UDP based file transfer protocols, we use an efficient algorithm to keep track of lost pockets and we re-transmit only the missing data.

With much fewer acknowledgments than any other TCP based protocol, the file transfer speed is not affected by the latency. And the speed loss is linear to the pocket loss (Which is impossible with large Window Sizes)

We also use our own built-in congestion control that is immune to latency and takes into the account the average latency of the link before slowing down.

We have an on-line calculator on our web site that provides a comparative of TCP over our UDP protocol. http://www.filecatalyst.com/web_demos/comparison_tool.html

I recognize that this is plug for a commercial product however this article explains exactly the same problem that we have been trying to fix for the last 5 years.

]]> By: knuckles http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-distance-links/comment-page-2/#comment-7486 knuckles Mon, 04 Jul 2011 21:56:20 +0000 http://www.bradhedlund.com/?p=74#comment-7486 Hi...i'm expecting about 1.5 Mbps on a link that i have. UDP works fine, however, TCP has yielded results close to 0.022 Mbps (essentially nothing!). Would the above tweaks be done on both ends of the network (being both PCs)? And also should a TcpWindowSize be added to the Interface Registry key where the network interface details exist? -->(HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ServicesTcpip\Parameters, Tcpip\Parameters\Interface) Thanks! Hi…i’m expecting about 1.5 Mbps on a link that i have. UDP works fine, however, TCP has yielded results close to 0.022 Mbps (essentially nothing!). Would the above tweaks be done on both ends of the network (being both PCs)? And also should a TcpWindowSize be added to the Interface Registry key where the network interface details exist? –>(HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\ServicesTcpip\Parameters, Tcpip\Parameters\Interface)

Thanks!

]]> By: O3B and Google tag team: Rural Africa’s redemption? « Tom Makau http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-distance-links/comment-page-2/#comment-6592 O3B and Google tag team: Rural Africa’s redemption? « Tom Makau Tue, 26 Apr 2011 08:42:21 +0000 http://www.bradhedlund.com/?p=74#comment-6592 [...] reach in a long time. To see how low latency is related to higher throughput see this tutorial here. The O3B idea is a great one and deserves all the support it can get so as to make it a [...] [...] reach in a long time. To see how low latency is related to higher throughput see this tutorial here. The O3B idea is a great one and deserves all the support it can get so as to make it a [...]

]]> By: Rolf Wiklund http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-distance-links/comment-page-2/#comment-6443 Rolf Wiklund Thu, 14 Apr 2011 11:17:54 +0000 http://www.bradhedlund.com/?p=74#comment-6443 Hi Brad. It looks that the window size is more important than the MTU? Do you have any calc. about the MTU size impact? I thinking mostly how to solv throughtput issues in DCI (40km) Thanks Rolf Hi Brad.
It looks that the window size is more important than the MTU?
Do you have any calc. about the MTU size impact?

I thinking mostly how to solv throughtput issues in DCI (40km)

Thanks
Rolf

]]> By: soulhacker http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-distance-links/comment-page-2/#comment-6423 soulhacker Wed, 13 Apr 2011 06:53:00 +0000 http://www.bradhedlund.com/?p=74#comment-6423 I just wonder how the latency comes out? If tcp mss is considered. Because the latency rises when tcp mss grows. I just wonder how the latency comes out? If tcp mss is considered. Because the latency rises when tcp mss grows.

]]> By: Abid http://bradhedlund.com/2008/12/19/how-to-calculate-tcp-throughput-for-long-distance-links/comment-page-2/#comment-4716 Abid Sun, 26 Dec 2010 16:12:54 +0000 http://www.bradhedlund.com/?p=74#comment-4716 Hi Brad, Thanks for excellent material that you have posted. We have WAN link of 45Mbps between point a and point B. We use ODG(oracle dataguard) to transfer arch files between point A & B. We have put WAAS devices at both points but still are getting 26Mbps of utilization. My n/w vendor/speciaalist asked me to increase the number of sessions ODG makes,we increased it to 9 from 4. However problem persists. What i understand is: 1: The throughput is dependent on Latency and TCP window (WAAS vendors says he has tuned the device for max TCP window). 2: With WAAS devices in place, even one session should have shown utilization of 45Mbps. PLease let us know if we are missign on anything.. Thanks Abid Hi Brad,
Thanks for excellent material that you have posted. We have WAN link of 45Mbps between point a and point B. We use ODG(oracle dataguard) to transfer arch files between point A & B. We have put WAAS devices at both points but still are getting 26Mbps of utilization. My n/w vendor/speciaalist asked me to increase the number of sessions ODG makes,we increased it to 9 from 4. However problem persists. What i understand is:
1: The throughput is dependent on Latency and TCP window (WAAS vendors says he has tuned the device for max TCP window).
2: With WAAS devices in place, even one session should have shown utilization of 45Mbps.

PLease let us know if we are missign on anything..

Thanks
Abid

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