A "Dedicated Load Balancer(s)" option will be included in the list of modifiable domain settings if your LON-CAPA domain contains more than one server or VM.
If you chose to designate one of your servers/VMs as a load balancer, you can configure balancing behavior as follows:
This determines which of your servers will host user sessions (by default) after log-in via the load balancer server. You can separate destinations into "primary" and "default". The least loaded of the primary servers will be selected, unless all primary servers are considered 100% loaded, in which case the least loaded of the default servers will be selected.
The choice of server/VM to host user sessions for particular types of user can be further configured, by choosing an action for particular user types. The chosen action will override the default behavior. The choice of user types includes the various affiliations defined for the institution (e.g., Faculty, Staff etc.). If users are not affiliated with any institutional group, they can be accommodated within the default "Other users" type which is provided automatically. If no status types are defined for your domain, this default group is entitled "All users".
In addition to type based on affiliation, there are additional types:
If an institution runs a library server with multiple domains, the server selected to be the load balancer can be different from the particular domain for which balancing is being configured. Two other additional types are available where the load balancer's domain and domain being configured match:
In all but the last case, the options available are:
In the last case (i.e., users whose home domain is not on any of the servers/VMs you manage), the options are: (a) Offloads to default destinations, (b) Offloads to user's home server, (c) Offloads to Load Balancer in user's domain, (d) No offload
LON-CAPA expects the remote IP address of the client web request to be the same at the authentication stage on the load balancer, and then subsequently, following attempted session migration to the offload server. Where IPs do not match (e.g., a user is accessing LON-CAPA using an internet connection provided by a cellular network, where IP addresses are pooled and can change between requests), you can set how that situation should be handled. The options are:
If the load balancing server's domain and the domain being configured are the same, you will select one of these options separately for (a) Single Sign On (SSO) users from your domain, and also (b) for both non-SSO users from your domain, and for users from other domains in the LON-CAPA network (if you have joined a cluster). If your institution maintains multiple domains then a load balancer can have a different domain from the domain you are currently configuring. In that instance you will select one of these options separately for (a) SSO users from your domain and (b) non-SSO users from your domain.