====== How to Enable HTTP/2 ======

LiteSpeed Web Server has supported HTTP/2 out of the box since Enterprise Version 5.0. HTTP/2 and SPDY are enabled by default for SSL listeners.

Some things to keep in mind:
  * If using a front-end SSL proxy server, enabling SPDY or HTTP/2 on LiteSpeed Web Server will have no effect, as front-end SSL proxies are not capable of forwarding SPDY and HTTP/2 requests.
  * HTTP/2 requires OpenSSL 1.0.2 as minimum. OpenSSL versions less than 1.0.2 will force HTTP/2 connections to HTTP/1. However, LiteSpeed Enterprise Web Server is staticly linked with latest OpenSSL 1.0.2 release and does not depend on the OpenSSL version installed in the system. 
  * HTTP/2 should work out of box for all HTTPS sites with LiteSpeed. Although HTTP/2 specification does not require TLS, TLS is required by browser implementations.

You can enable HTTP/2 with the ''SpdyEnabled'' directive in the ''httpd.conf'' configuration file, or via the WebAdmin Console. 

===== Via Configuration File =====

In ''httpd.conf'', use the ''SpdyEnabled http2'' directive to enable HTTP/2, like so:

  <IfModule LiteSpeed>
  SpdyEnabled http2
  </IfModule>

Other valid parameters are ''spdy2'', ''spdy3'', ''http3'' and ''off''. 

All protocols are enabled by default. As such, if you wish to use SPDY, HTTP/2, and HTTP/3, there is no need for a ''SpdyEnabled'' directive at all.

When you use this directive to explicitly enable one or more protocols, anything not selected will be //disabled//. For example, ''SpdyEnabled http2'' will enable HTTP/2, while SPDY and HTTP/3 will be disabled. 

===== Via WebAdmin Console =====

{{ :litespeed_wiki:config:spdyenabled.png?600 |}}

In the WebAdmin Console, you can find the **Enable SPDY/HTTP2/HTTP3** option in the **SSL** tab for both **Listeners** and **Virtual Hosts**. Select the ''HTTP/2'' option to enable HTTP/2. 

====== How to check if HTTP/2 is enabled? ======

Though you can use the third party web tools to check, the most common and easy way to check is through browser's developer tools. 
h2 and http/2 mean HTTP/2 has been enabled for your server.

{{ :litespeed_wiki:config:http2-protocal.png?800 |}}

If you use third-party web tools, it could show as the following:
{{ :litespeed_wiki:config:http2-checker-tool.png?600 |}}