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Developer(s) cFos Software GmbH
Initial release 7 July 2004; 11 years ago (2004-07-07)
Stable release 10.10 / 9 September 2015; 4 months ago (2015-09-09)
Operating system Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Vista, Windows XP, Windows Server 2003 and Windows Server 2008
Platform IA-32 and x86-64
Type Traffic shaping
License Shareware

cFosSpeed is a software solution for traffic shaping for the Windows operating system. It aims to improve Internet latency while maintaining high transfer rates. The program attaches itself as a device driver to the Windows network stack where it can then perform packet inspection and layer-7 protocol analysis.

As such, it is marketed to online gamers and VoIP users.

A version of the software is bundled with some Gigabyte motherboards under the name "Gigabyte Speed"[1] and some ASRock motherboards as "XFast LAN".[2]

Operational summary[edit]

The software divides data packets into different traffic classes. This is achieved through a number of filtering rules that can be set by the user. Data traffic can thus be classified and prioritized by program name, by layer-7 protocol, by TCP or UDP port numbers, by DSCP tags as well as many other criteria.

Outgoing traffic is not sent out indiscriminately. Instead, data packets are first queued and then sent out in order of their priority. This way, data that is needed immediately is transmitted before less time-critical data.[3]

Thus, even if large amounts of data are transferred at the same time, traffic shaping can keep interactive connections like SSH sessions, VNC sessions, VoIP calls, online games or other time-critical programs responsive. .[4][5] This is because the sender will only send out data after the receiver has acknowledged reception of older data (TCP flow control).

cFosSpeed also tries to reduces network congestion for downloads by lowering the TCP window size to keep the sender from sending too much data at once.

In addition, cFosSpeed contains a packet filter firewall, time and volume online budgets a skinnable transfer monitor and several other special purpose features.[6] It has a filter language that allows experts to write their own traffic classifications.[7]

Similar Products[edit]


  1. ^ "GIGABYTE - Motherboard - Socket 1150 - GA-Z87X-D3H (rev. 1.x)". Gigabyte website. Gigabyte Technology. Retrieved 2015-10-03. 
  2. ^ "ASRock XFast LAN - cFos Software". cFos website. cFos Software GmbH. Retrieved 2014-01-14. 
  3. ^ Lüders, Christoph; Winkler, Martin (20 February 2008). "Tweaking TCP/IP". The H Online. Heise Media UK Ltd. 
  4. ^ "How does traffic shaping in cFosSpeed work?". cFos website. cFos Software GmbH. Retrieved 18 January 2011. 
  5. ^ "cFosSpeed 6.10" (in German). Heise Zeitschriften Verlag. Retrieved 18 January 2010. 
  6. ^ "List of cFosSpeed's features". cFos website. cFos Software GmbH. Retrieved 18 January 2011. 
  7. ^ "Filter language used to classify packets". cFos website. cFos Software GmbH. Retrieved 18 January 2011. 

External links[edit]