Global and Local Load Balancing

Introduction

From the previous lesson, it may seem like load balancing is performed only within the data center. However, load balancing is required at a global and a local scale. Let’s understand the function of each of the two:

• Global server load balancing (GSLB): GSLB involves the distribution of traffic load across multiple geographical regions.
• Local load balancing: This refers to load balancing achieved within a data center. This type of load balancing focuses on improving efficiency and better resource utilization of the hosting servers in a data center.

Let’s understand each of the two techniques below.

Global server load balancing

GSLB ensures that globally arriving traffic load is intelligently forwarded to a data center. For example, power or network failure in a data center requires that all the traffic be rerouted to another data center. GSLB takes forwarding decisions based on the users’ geographic locations, the number of hosting servers in different locations, the health of data centers, and so on.

In the next lesson, we’ll also learn how GSLB offers automatic zonal failover. GSLB service can be installed on-premises or obtained through Load Balancing as a Service (LBaaS)LBaaS is a cloud-based load balancing technique that follows a pay-per-use model. LBaaS offers the flexibility of automatic scaling up or down depending upon the traffic load..

The illustration below shows that the GSLB can forward requests to three different data centers. Each local load balancing layer within a data center will maintain a control plane connection with the GSLB providing information about the health of the LBs and the server farm. GSLB uses this information to drive traffic decisions and forward traffic load based on each region’s configuration and monitoring information.