Global Load Balancer Service

A knowledge base article about Global Load Balancer Service provided by the UC Berkeley IT Service Hub - Knowledge Portal

The bIT Load Balancer service supports global load balancing (GSLB) to provide site redundancy in addition to the traditional but site specific server load balancing. GSLB can be used by departments to distribute load between different sites (traditional load balancing) or provide fail-over to a secondary site during outages or maintenance. 

GSLB works by providing different domain name server (DNS) responses based on customer defined criteria (such as a server being offline, failing a test, or identifying itself as active). GSLB is currently in use on the UCB network providing site redundancy for some voice and data services ensuring the reliability of key services.

Customers do not need dedicated SLB service for GSLB, but can if they prefer. GSLB configuration that can be implemented in existing SLB partitions, but there are two requirements that must be met.

  1. Departments must have a SLB partition at two or more SLB supported sites (gslb does not work with a single site)
  2. Departments must delegate a DNS zone to GSLB service (for example department.berkeley.edu can have gslb.department.berkeley.edu)

The process for implementing GSLB is as follows:

  1. If you do not already have SLB partitions in two or more sites submit a load balancer request for new/additional service
  2. Submit a hostmaster request for the following
    1. Identify that you are preparing a GSLB implementation
    2. Request a host record for each SLB partition used for your GSLB service (for example gslb1.department.berkeley.edu on 10.10.100.0/24, gslb2.department.berkeley.edu on 10.20.200.0/24)
    3. Request a DNS zone be reserved for use with the service (for example gslb.department.berkeley.edu)
  3. Configure your GSLB service as needed and test to be sure the hosts requested in step #2 respond to queries as expected
  4. Submit a hostmaster request requesting that the reserved domain be delegated to your GSLB service, and if you need any links made into that domain (such as www.domain.berkeley.edu being an alias to www.gslb.domain.berkeley.edu)

Step by step instructions on configuring GSLB can be found in the Configuring Global Server Load Balancing article.