Microsoft Azure Network Traffic Management

Network Traffic Management uses network monitoring tools and management techniques such as bandwidth monitoring, deep packet inspection, and application-based routing to ensure optimal network operation.

In doing so it helps maximize the performance and security of existing networks. It also allows for the identification of network-intensive operations that can be incorporated into network planning and growth strategies.

Network Traffic Management is used alongside other optimization techniques like Application Traffic Management as part of an overall Application Delivery Network solution.

Availability Set

Availability Set is a logical grouping capability for isolating VM resources from each other when they’re deployed. By deploying your VMs across multiple hardware nodes Azure ensures that if hardware or software failure happens within Azure, only a sub-set of your virtual machines is impacted and your overall solution is safe and in working condition.

It provides redundancy for your virtual machines. An Availability set spreads your virtual machines across multiple fault domains and update domains.

Fault Domain

• Azure Fault domains define the group of virtual machines that share a common power source and network switch.
• Each and every fault domain contains some racks and each rack contains a virtual machine.
• All the resources in the fault domain become unavailable when there is a failure in the fault domain.

Update Domain

• Virtual machines get update domains automatically once they are put inside the availability set.
• All virtual machines within that update domain will reboot together.
• They are used for patching virtual machines.
• Only one update domain can be updated at a time.                                                                                                                                                                         

                                                              

Azure Traffic Manager     

Azure Traffic Manager allows you to regulate the distribution of user traffic by using DNS to direct requests to the most appropriate service endpoint supported on a traffic-routing method and therefore the health of the endpoints.                                                                             

Azure traffic manager selects an endpoint based on the configured routing method. It supports a variety of traffic-routing methods to suit different application needs. After the selection of endpoints, the client is connected directly to the appropriate service point. It also provides endpoint health checks and automatic failover. It also enables you to build a highly available application that is resilient to failure, including the failure of an entire Azure region.

                                         

Traffic Manager routing methods

Azure Traffic Manager supports six traffic-routing methods to determine how to route network traffic to the various service endpoints. For any profile, Traffic Manager applies the traffic-routing method associated to it to each DNS query it receives. The traffic-routing method determines which endpoint is returned in the DNS response.

The following traffic routing methods are available in Traffic Manager:

• Priority: Select Priority routing when you want to have a primary service endpoint for all traffic. You can provide multiple backup endpoints in case the primary or one of the backup endpoints is unavailable.
• Weighted: Select Weighted routing when you want to distribute traffic across a set of endpoints based on their weight. Set the weight the same to distribute evenly across all endpoints.
• Performance: Select Performance routing when you have endpoints in different geographic locations and you want end users to use the "closest" endpoint for the lowest network latency.
• Geographic: Select Geographic routing to direct users to specific endpoints (Azure, External, or Nested) based on where their DNS queries originate from geographically. With this routing method, it enables you to be in compliance with scenarios such as data sovereignty mandates, localization of content & user experience and measuring traffic from different regions.
• Multivalue: Select MultiValue for Traffic Manager profiles that can only have IPv4/IPv6 addresses as endpoints. When a query is received for this profile, all healthy endpoints are returned.
• Subnet: Select Subnet traffic-routing method to map sets of end-user IP address ranges to a specific endpoint. When a request is received, the endpoint returned will be the one mapped for that request’s source IP address.                                                                      

Priority traffic-routing method :-

Traffic Manager profile contains a prioritized list of service endpoints. By default, Traffic Manager sends all traffic to the primary (highest-priority) endpoint. If the primary endpoint isn’t available, Traffic Manager routes the traffic to the second endpoint. If both the primary and secondary endpoints are not available, the traffic goes to the third endpoint, and so on. Availability of the endpoint is based on the configured status (enabled or disabled) and the ongoing endpoint monitoring that is set up.

                                              

Weighted traffic-routing method :-      

Choose weighted when you want to distribute traffic across a set of endpoints, either evenly, or based on different weights. The weight is an integer from 1 to 1,000. For each DNS query received, Traffic Manager randomly chooses an available endpoint. The probability of choosing an endpoint is based on the weights assigned to all available endpoints.                                                                                                                             

                                                                     

Performance traffic-routing method :-

Performance traffic routing method connects users with the server that performs best for the user. If you have endpoints in different geographic locations, you can use performance routing to send users to the endpoint that has the best performance for the user. It might be better performing because it’s physically closer to the user, but it might also be due to congestion on internet network connectivity.

To choose the best endpoint to use, this routing method uses an internet latency table, which actively tracks network latency to the endpoints from locations around the globe. When a user makes a request, Traffic Manager returns the best performing endpoint based on the location of the request.                                                

Geographic traffic-routing method :-

With the geographic routing method, users are directed to specific endpoints based on where their DNS query originates. Using this method enables you to geo-fence content to specific user regions. For example, European users can be directed to an endpoint in Europe that has specific terms and conditions for regional compliance. Users in China can be directed to an endpoint that has been localized in Mandarin.

                                                               

Multi-value traffic-routing method :-

You can use the multi value routing method to get multiple healthy endpoints in a single DNS query response. The caller can make client-side retries with other endpoints if an endpoint is unresponsive. This pattern can increase the availability of a service and reduce the latency associated with a new DNS query to obtain a healthy endpoint.

Subnet traffic-routing method :-

This method maps the set of user IP address ranges to specific endpoints within a Traffic Manager profile. When a request is received, the endpoint returned will be the one mapped for that request’s source IP address. For example, using subnet routing, a customer can route all requests from their corporate office to a different endpoint, where they might be testing an internal-only version of the app. Another scenario is if you want to provide a different experience to users who connect from a specific ISP (for example, to block users from a specific ISP).