Designing and Implementing Application Delivery Services

In an increasingly connected world where applications and services are hosted on the cloud, load balancers are a critical component of any IT infrastructure. They ensure that traffic is distributed evenly among multiple service instances, thereby improving application performance, reliability, and scalability. Microsoft Azure provides a range of options to meet the diverse needs of its customers.

In this chapter, we will discuss the four main load-balancing services in Azure, look at things to consider when designing and implementing these services, and help you to understand how to select the best service for your application.

In this chapter, we will cover the following topics:

• Understanding Azure’s load-balancing and application delivery services
• Designing and implementing an Azure Load Balancer service
• Designing and implementing an Azure Application Gateway service
• Designing and implementing...

Technical requirements

To follow along with the instructions in this chapter, you will need the following:

• A PC with an internet connection
• An Azure subscription

Understanding Azure’s load-balancing and application delivery services

Application delivery and load balancing are two related but distinct concepts in the world of networking and web services. Load balancing refers to the distribution of incoming network traffic across multiple servers or resources in order to improve the overall performance, availability, and scalability of a service.

On the flip side, application delivery pertains to making software applications available to both internal users and external customers. It encompasses a wider range of functionalities beyond load balancing, including securing the application, optimizing application performance, and managing user authentication and access control.

Azure offers various services for load balancing and/or application delivery that we can leverage to distribute incoming network requests across application instances or handle application delivery functionalities. These services include Traffic Manager, Load...

Designing and implementing an Azure Load Balancer service

Azure Load Balancer is a pass-through network load balancer that operates at Layer 4 of the Open Systems Interconnection (OSI) model. It can distribute network traffic for all Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) protocols. Because it does not modify or analyze received traffic, it is the most performant load-balancing option in Azure.

What is a pass-through network load balancer?

A pass-through network load balancer is a type of load balancer that simply forwards traffic to backend services without modifying or analyzing the content. Unlike other types of load balancers, such as application load balancers, a pass-through network load balancer does not perform any application-level processing, such as SSL termination, header manipulation, or content inspection. Instead, it simply distributes incoming traffic across a pool of backend servers based on configured rules, such as round-robin...

Designing and implementing an Azure Application Gateway service

Azure Application Gateway is a regional service that provides Layer 7 load balancing, SSL/Transport Layer Security (TLS) termination, and WAF capabilities. It is optimized for web traffic and enables you to manage traffic to your web applications.

Understanding Azure Application Gateway tiers

When implementing Azure Application Gateway, one of the first decisions that we need to make is the service tier to implement. Azure Application Gateway offers four service-tier options: Standard (V1), Standard V2, WAF (V1), and WAF V2 (Figure 9.25):

Figure 9.25 – Azure Application Gateway service tiers

The Standard tier is suitable for small-to-medium-scale applications that require basic load-balancing and SSL termination capabilities. It supports features such as SSL offload, session affinity, and URL-based routing. It does not, however, support autoscaling or WAF capabilities. This tier...

Designing and implementing an Azure Front Door load balancer service

Azure Front Door is a service that delivers applications and caches content using a network of globally distributed edge nodes. It offers capabilities such as global load balancing, dynamic and static content acceleration, and web application protection at the global edge for web applications and APIs. Unlike the regional Application Gateway, Front Door is a global service that can serve requests and content for endpoints distributed across multiple Azure regions or even those outside of Azure.

In Figure 9.37, the Front Door service receives client requests from end users through a nearby point of presence (or edge location) using an anycast public IP address. It then leverages Microsoft’s high-throughput backbone network to accelerate delivery to the backend application instead of routing traffic entirely over the public internet. Azure Front Door has over 150 points of presence (PoP) distributed globally...

Designing and implementing an Azure Traffic Manager service

Azure Traffic Manager is a DNS-based traffic load balancer that routes incoming client requests to the most suitable endpoint based on routing rules configured by the user. It is important to note that Traffic Manager is not an inline load-balancing service like the three other services that we have discussed so far. Instead, it uses DNS to redirect a client to an available backend target.

Figure 9.64 provides an overview of the Traffic Manager request routing process:

Figure 9.64 – Traffic Manager request routing process

The request routing process in Azure Traffic Manager involves several steps, as explained next using an example:

1. When the client needs to resolve the name partners.contoso.com, it sends a DNS query to its configured recursive DNS service. This service contacts the various authoritative DNS services across the internet to resolve the DNS name. For example, let...

Choosing an optimal load-balancing and application delivery solution

The Azure load-balancing decision tree takes into account various factors when selecting the appropriate load-balancing options. The Help me choose default tab in Azure load balancing considers the following factors:

• Traffic type: Is the application web-based (HTTP/HTTPS)? Is it a public or private application?
• Global versus regional: Do you need to load balance VMs or containers within a VNet? Or do you need to load balance scale units/deployments across different regions, or both?
• Availability: What is the required SLA for the application?
• Cost: In addition to the cost of the load-balancing service itself, consider the cost of managing a solution built on that service.
• Features and limitations: What are the overall limitations of each load-balancing service? Refer to the service limits to identify the constraints.

The flowchart shown in Figure 9.67 provides guidance on selecting the...

Summary

In this chapter, we delved into the topic of load-balancing and application delivery services in Azure. We discussed the importance of load balancing for ensuring the HA and scalability of applications and covered the design and implementation of several Azure load-balancing solutions, including Azure Load Balancer, Azure Application Gateway, Azure Front Door, and Azure Traffic Manager.

We explored the differences between these solutions and their various use cases and provided guidance on how to choose the optimal solution based on specific requirements. This chapter equipped you with a solid understanding of Azure’s load-balancing and application delivery services and the skills needed to design and implement these solutions.

In the next chapter, we will expand on our understanding of Azure networking by concentrating on establishing private connectivity to Azure platform services. See you there!