Cluster Communication among Clustered Connect Servers

This article addresses how to make sure every URL int a Connect cluster pops up like your grandmother’s trustworthy old pop-up-toaster.  If some published content will not play or display properly from your Connect cluster, do the following:

• Make sure that the load balancing device in front the Connect cluster is not using sticky sessions or session awareness.
• If you are using a Big-IP LTM, make sure that Nagle’s Algorithm is turned off .
• Make sure that Clustered servers communicate with each other on ports 8506 and 8507. A simple netstat -an from the command prompt on each server will make certain each server is listening on 8507.
• Don’t try to cheat on the number of documented VIPs required on the load-balancing device or SSL accelerator. Only one VIP is not the right answer.
• When the servers cannot communicate, trouble ensues.Clustered servers need to be able to communicate with each other on port 8507. When they cannot communicate, the links to content will be broken and end users may experience hanging videos or unavailable content.
• Search in your debug log for “cluster-”
  • [01-31 18:20:23,729] cluster-8507-696969 (INFO) MirrorHandler: waiting for commands”    2014-02-10T16:30:23.739-0600….
  • If you do  not see cluster-8507 then there is a replication communication problem on 8507

• To help facilitate troubleshooting, during setup and during upgrades, if possible, allow the servers to have external access – at least allow the monitored and screened ability to toggle external access on and off by special request if needed. This will allow you access to Adobe’s license server and also to troubleshooting tools.
• Install telnet on each server. Telnet is a great test tool. Placing telnet on each server and actually testing connectivity to each and from each server on ports 8506 and 8507 is prudent.
• It is also prudent to have a useful browser on each server. I often install FireFox on each server along with the latest available Flashplayer. You may want to install Flashplayer on IE as well even though enhanced security will render it a challenge to use for any useful troubleshooting purposes. Useful flash-enabled browsers will facilitate direct tests on any problematic content on the servers from the servers thereby eliminating network and load-balancing variables when isolating issues.