F5 Drops WebSockets

Problem: F5 LTM is used als load balancer for multiple web servers. When the client opens a websocket connection to the web server, the connection is closed.

Discussion: F5 LTM version before 11.6.0 has a bug in the request_log module (profile). The “request_log” module crashes and drops the connection. The bug is a known issue:


Solution: If you cannot update. You can apply an iRule as a work arround:

  if { [string tolower [HTTP::header Upgrade]] contains "websocket" } {

This iRule disables http handling and logging for websocket requests.