If you are a web administrator, you know that traffic is a volatile resource. It can come from anywhere, anytime, and in unpredictable volumes. If it is not well-regulated, your servers could crash and bring the business to a grinding halt.
Fortunately, you can avert this situation using load balancing. Load balancing can be defined as the process of distributing incoming traffic across multiple servers or endpoints to optimize the performance, availability, and scalability of applications. It ensures that no single server or endpoint becomes overloaded and the spikes in demand or unexpected failures are dealt with.
However, load balancing is not a silver bullet for your traffic management concerns as it comes with a unique set of challenges. For example, you need to handle different kinds of scenarios including dynamic and heterogenous web environments, multiple regions and zones, different protocols and traffic, cloud service integrations, and most importantly, the security of client and server communications.
If your org uses Microsoft Azure, then you have several services that can help negate these challenges.
Here is a list of the select few:
- Azure Front Door: It is a global application delivery network that offers load balancing and site acceleration for web applications.
- Azure Traffic Manager: It is a DNS-based traffic load balancer that empowers you to distribute traffic across clouds, regional backends, or hybrid on-premises services.
- Azure Application Gateway: A regional load balancer that operates at the application layer (Layer 7) and offers load balancing for web applications or other HTTP(S) endpoints.
- Azure Load Balancer: A regional load balancer that runs at the network layer (Layer 4) and offers load balancing for any TCP or UDP traffic.
Again, there is no single service amidst these that can solve all traffic volatility challenges. In other words, they have their pros and cons that make them ideal and less ideal for various business use cases. Comparing and contrasting them is necessary to make a long-term decision.
Let us begin with Azure Front Door.
Azure Front Door
At its core, Azure Front Door is a service that helps you deliver your web applications quickly and securely to your global users. It works by routing your traffic to the closest or best-performing backend server, based on your rules and settings.
Important features
SSL offloading
Azure Front Door can terminate SSL connections at the edge and use integrated certificate management to simplify the configuration and maintenance of SSL certificates. This reduces the load and latency on your backend servers and improves the security of your communication.
Path-based routing
Azure Front Door can route your traffic based on the URL path of the request, allowing you to host multiple web applications on the same backend pool or direct traffic to different backend pools based on the content type or functionality. You can also use request rewriting to modify the URL path before sending it to the backend.
Fast failover
Azure Front Door can detect and avoid unhealthy backends using health probes and automatically redirect your traffic to the next available backend within seconds. This ensures high availability and resilience for your applications and content.
Caching
Azure Front Door can cache static content at the edge locations and serve it directly to your users, truncating the load and latency on your backend servers and improving the performance and user experience of your applications and content. You can customize the caching behavior using cache rules and expiration settings.
Web application firewall
Azure Front Door can protect your web applications from common web vulnerabilities and malicious attacks using a web application firewall (WAF) that is seamlessly attached to your Front Door configuration. You can use predefined or custom WAF policies to define the rules and actions for filtering and blocking unwanted traffic.
Use cases or ideal scenarios
Delivering dynamic web content globally
Azure Front Door can provide load balancing and site acceleration for web applications by routing traffic to the closest or best-performing backend server using features like SSL offload, caching, web application firewall, and path-based routing. This drastically improves user experience and application performance while ensuring they are safe from cybersecurity threats.
Hosting and enabling communication between applications
Hosting multiple web applications on the same backend pool, providing secure communication between clients and servers, enforcing web application security policies, etc. can be easily performed using Azure Front Door.
Providing failover and disaster recovery options
Azure Front Door offers DNS-centric traffic load balancing to distribute traffic across regional backends, clouds, or hybrid on-premises services. It uses features such as geographic routing, performance routing, priority routing, weighted routing, and endpoint health monitoring.
Azure Traffic Manager
This variant deals with DNS-centric traffic load balancing and empowers you to disperse traffic optimally to services across Azure regions spread globally while offering responsiveness and high availability. It functions only at the domain level and uses DNS queries to determine the user location and health of the endpoints. It then returns the DNS address of the most appropriate endpoint based on your routing method.
Use cases
When you want to route traffic systematically, you can fix the routing method based on:
- Priority
- Performance
- Geographic
- Weighted
- Subnet
- Multi-value
You can also use nested profiles to combine different routing methods for more complex scenarios.
Continuous monitoring of endpoints
Azure Traffic Manager monitors the health of your endpoints using HTTP or HTTPS probes and automatically directs traffic to the next available endpoint when an endpoint fails. This ensures high availability and resilience for your applications and services.
Ensuring support for external, non-Azure endpoints
Azure Traffic Manager can load balance traffic across any Internet-facing service hosted inside or outside Azure. This enables you to use Traffic Manager with hybrid cloud and on-premises deployments, including the “migrate-to-cloud”, “burst-to-cloud”, and “failover-to-cloud” scenarios.
Integrating other Azure load balancing services
Azure Traffic Manager can work with other Azure load balancing services such as Azure Front Door, Azure Application Gateway, and Azure Load Balancer to achieve higher levels of performance and availability for your applications. For example, you can use Traffic Manager to distribute traffic across multiple regions or clouds, and then use Front Door or Application Gateway to load balance traffic within a region or a virtual network.
Azure Application Gateway
Azure Application Gateway is a web-based traffic load balancer that allows you to handle traffic to your web applications. It works by routing your traffic to a pool of backend servers based on various rules and health probes.
It has overlapping features such as path-based routing and a web application firewall with Azure Front Door.
Important Features
SSL termination
Azure Application Gateway can terminate SSL connections at the gateway and use integrated certificate management to simplify the configuration and maintenance of SSL certificates. This reduces the load and latency on your backend servers and improves the security of your communication.
URL path-based routing
Azure Application Gateway can route your traffic based on the URL path of the request, allowing you to host multiple web applications on the same backend pool or direct traffic to different backend pools based on the content type or functionality. You can also use request rewriting to modify the URL path before sending it to the backend.
Cookie-based session affinity
Azure Application Gateway can maintain session affinity by using cookies. This ensures that subsequent requests from a user are routed to the same backend server during a session.
Web applications that store user-specific information on the server side can benefit significantly from cookie-based session affinity.
Web application firewall
Like Azure Front Door, Azure Application Gateway also offers a web application firewall that can safeguard your web applications from common web vulnerabilities and cyberattacks. This firewall is attached to the gateway configuration.
Azure Load Balancer
Azure Load Balancer is a regional load balancer that operates at the network layer (Layer 4) and provides load balancing for any TCP or UDP traffic. It is mostly used to handle internal or external traffic to virtual machines or virtual machine scale sets within a virtual network or across zones or regions.
Important Features
High availability
Azure Load Balancer can distribute incoming traffic across multiple backend servers or endpoints within a region, based on rules and health probes that you configure. This ensures that your applications and services are always available and can handle spikes in demand or unexpected failures.
Low latency and high throughput
Azure Load Balancer can provide low latency and high throughput for your applications and services as it operates at the network layer (Layer 4) and scales up to millions of flows for the entire TCP and UDP traffic.
Outbound connectivity
Azure Load Balancer can also support outbound connectivity for virtual machines by translating their private IP addresses to public IP addresses. This enables your virtual machines to communicate with the Internet or other Azure services.
Port forwarding
Azure Load Balancer can also enable port forwarding which allows you to access virtual machines in a virtual network via public IP address and port. This is handy if you require regular remote desktop access, SSH access, or application debugging.
A comparison of different Azure load balancing solutions
We know how the top load-balancing solutions from Azure work and how they are beneficial. However, for decision-making, a detailed analysis of their differences is necessary.
The table below summarizes the differences.
| Differentiator | Azure Front Door | Azure Traffic Manager | Azure Application Gateway | Azure Load Balancer |
| Scope | Global | Global | Regional | Regional or Global |
| Traffic Type | HTTP(S) | Non-HTTP(S) | HTTP(S) | Non-HTTP(S) |
| Routing Method | Path-based | DNS-based | Path-based | Port-based |
| SSL Offload | Yes | No | Yes | No |
| Caching | Yes | No | No | No |
| Web Application Firewall | Yes | No | Yes | No |
| Session Affinity | Cookie-based | No | Cookie-based | No |
| Outbound Connectivity | No | No | No | Yes |
Let us take one step forward and see which load-balancing solution suits various use cases or scenarios.
| Use Case/Scenario | Azure Front Door | Azure Traffic Manager | Azure Application Gateway | Azure Load Balancer |
| Delivering dynamic web content to global users, optimizing user experience and performance, protecting web applications from malicious attacks, etc. | ✅ | ✅ | ✅ | ❌ |
| Hosting multiple web applications on the same backend pool, providing secure communication between clients and servers, enforcing web application security policies, etc. | ✅ | ❌ | ✅ | ❌ |
| Directing users to the closest or best-performing backend service, providing failover and disaster recovery options, supporting multi-cloud or hybrid deployments, etc. | ✅ | ✅ | ❌ | ❌ |
| Maintaining session affinity by using cookies. | ✅ | ❌ | ✅ | ❌ |
| Distributing internal or external traffic to virtual machines or virtual machine scale sets within a virtual network or across zones or regions. | ❌ | ❌ | ❌ | ✅ |
| Supporting outbound connectivity for virtual machines by translating their private IP addresses to public IP addresses. | ❌ | ❌ | ❌ | ✅ |
| Enabling port forwarding for accessing virtual machines in a virtual network via public IP address and port. | ❌ | ❌ | ❌ | ✅ |
| Developing and testing environments, application-to-application communications, applications aimed at a narrow user base that share a common recursive DNS infrastructure (for example, employees of a company connecting through a proxy), etc. | ❌ | ✅ | ❌ | ❌ |
Final Thoughts
That brings us to the close of this guide that explored the different load-balancing solutions in Microsoft Azure and how they can help you improve your applications and services. Azure Front Door, Azure Application Gateway, Azure Traffic Manager, and Azure Load Balancer are all excellent load-balancing solutions and are unique in their way. However, the analysis represented in the tables above indicates that they are ideal for specific scenarios. There is no one-fit solution for all. You must do a thorough check of your business needs and long-term tech dependencies before making a final decision.
As one of the best cloud partners in the USA, Suyati offers Microsoft Azure services that are tailor-made according to our customer’s requirements. If you have any questions, don’t hesitate to reach out to us at services@suyati.com.
