Load balancing is distribution of workloads across multiple computing resources in order to optimize resource use, maximize throughput, minimize response time, and avoid overloading any single resource. It can also improve availability by sharing a workload across redundant computing resources.
Azure provides a suite of fully managed load-balancing solutions for your scenarios.
- If you are looking to do DNS based global routing and do not have requirements for Transport Layer Security (TLS) protocol termination (“SSL offload”), per-HTTP/HTTPS request or application-layer processing, review Traffic Manager.
- If you want to load balance between your servers in a region at the application layer, review Application Gateway.
- To do network layer load balancing, review Load Balancer.
To understand different options please refer to Load Balancing Decision Tree below. (Source: Understand Azure load balancing)
Azure Front Door is a global, scalable entry-point that uses the Microsoft global edge network to create fast, secure, and widely scalable web applications. It works as a global HTTP/HTTPS layer load balancer. With Front Door, you can transform your global consumer and enterprise applications into robust, high-performing personalized modern applications with contents that reach a global audience through Azure. Supports routing methods: Latency (route to the closest region), Priority, Weighted, Session Affinity. Supports Rate Limiting.
Azure Application Gateway is a web traffic (HTTP/THHPS layer) load balancer that allows to manage traffic to web applications. Traditional load balancers operate at the transport layer (OSI layer 4 – TCP and UDP) and route traffic based on source IP address and port, to a destination IP address and port. Application Gateway can make routing decisions based on additional attributes of an HTTP request, for example URI path or host headers. Supports TSL termination at the gateway (add an SSL wildcard certificate).
Below is visualization of Application Gateway processing request.
To distribute traffic, an application gateway uses several components.
Azure Traffic Manager is a DNS-based traffic load balancer. This service allows you to distribute traffic to your public facing applications across the global Azure regions. Traffic Manager also provides your public endpoints with high availability and quick responsiveness. Routing methods: Priority, Weighted, Performance, Geographic (route to specific region), Multivalue, Subnet.
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