IE8: 6 Connections Per Host

by Dylan SchiemannMarch 5th, 2008

The rumor is true… IE 8 will now allow six HTTP connections per host:

Six connections per host instead of two for broadband scenarios and a scriptable property allow for more improved performance by allowing parallelization of downloads in Internet Explorer 8. In addition, this increases functionality by ensuring a request is not blocked to a host if two connections already exist. Websites can optimize their downloads based on a scriptable property.

Perhaps this is the beginning of the end of the Dreaded 2 Connection Limit? Firefox, Opera, and Safari of course have had a default connection limit of 8 connections per server for some time now. I’m curious why they chose 6 instead of 8.

The downside of more connections is a potential increase in server resources, but this does make it much easier to reserve a connection for Comet and still have connections free for other resource requests.

10 Responses to “IE8: 6 Connections Per Host”

  1. Dan Says:

    For most websites I think this will be great. For most websites I visit, if the pages are dynamic, then most of the other requested files (images, css, js) are static. Since the majority of resources go towards handling the first dynamic request, whether or not I have only 2 connections, 6 or 8 should have negligible impact on most modern web servers.

  2. Jose M. Arranz Says:

    I don’t agree about Firefox, FireFox by default limits to 2 connections per host as HTTP mandates. I’m using the last 2.0 release.

    Try this
    long polling example
    with FireFox. Click two times over “Using Comet” link (every click opens a new cloned page, return to the original page).

  3. Jose M. Arranz Says:

    I forgot: the browser hangs

  4. Jens Hagel Says:

    firefox by default only allows 2 connections per server:

  5. The Internet Explorer 8 beta aftermath « Stone Ward Interactive Says:

    [...] Daily talks about the connection limit being raised from 2 to 6, great news for AJAX and Comet [...]

  6. DylanSchiemann Says:


  7. Comet Daily » Blog Archive » IE8 and JavaScript Download Concurrency Says:

    [...] the recent post IE 8: 6 Connections Per Host, several of the comments suggested that Firefox and other browsers only allow two connections per [...]

  8. High Performance Web Sites :: Roundup on Parallel Connections Says:

    [...] IE8: 6 Connections Per Host [...]

  9. Jens Hagel Says:

    i’ve tested the 2 connection problem with firefox. so if you have two “hanging” GET requests within the browser to the same server, you cannot send another request. so 2 connections is the limit not 8. with http/1.1 all connections are persistent so you only should consider network.http.max-persistent-connections-per-server.


  10. Lombardi Development Blog » Blog Archive » Using the GWT SuggestBox with RPC - Part Two Says:

    [...] limit here is at least four, apparently it’s actually eight. IE8 will allow six connections per host but I didn’t test [...]

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