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# pipe_timeout: Most under-documented Varnish parameter
- URL: https://www.frank.be/pipe_timeout-most-under-documented-varnish-parameter/
- Published: 2014-03-14T13:41:03.000Z
- Updated: 2026-06-21T17:37:37.000Z
- Author: Frank Louwers
- Tags: varnish

The title of this post says it all. `pipe_timeout` is the most undocumented Varnish Cache parameter.

It does what it says: it defines the timeout on `pipe` sessions. The default is 60 seconds, which is a bit short, as Varnish themselves recommend pipe for long downloads etc. Yes, if the long download is served directly from a webserver, the timeout doesn't matter.

However, if a script has to generate the document first, and doesn't send anything the first 60 seconds, the timeout kicks in, and Varnish will drop the client connection.

BTW: although it is a backend parameter, it seems you can't specify the parameter in your `default.vcl` backend section, but have to specify it as a start option (`-p pipe_timeout=300`) instead.