Load distribution with a number of Load Balancers

If a UMS server and load balancer are installed on a shared computer, the UMS server communicates with the thin clients via port 30002, otherwise via port 30001 as is customary with a single server installation. The Load Balancer always communicates with the thin clients via port 30001.

Load distribution to the load balancers can be performed as follows. When booting, IGEL thin clients attempt to establish contact with the UMS server in this order:

In a UMS High Availability network, the load balancers are automatically specified in the list of remote management servers in the local thin client configuration.

If the DNS entry igelrmserver or DHCP tag 224 is used in an HA network, the IP of a load balancer must be entered.

If neither this DNS entry nor the DHCP tag 224 is used, thin clients always connect to the first load balancer in the setup list, i.e. all thin clients are communicating with a single load balancer. The other load balancers are merely stand-bys and will be used only if the first load balancer in the list is not available.

To achieve load distribution between the load balancers, you can however use the DNS entry igelrmserver with a Round Robin DNS. To do this, the IP addresses of all load balancers are recorded in the DNS as a Resource Record Set for the igelrmserver entry (cf. http://en.wikipedia.org/wiki/Round-robin_DNS). The thin clients then connect randomly to one of the available load balancers, thus distributing the query load of all thin clients.