Load Balancing of requests coming from a single client

Question

I have a question regarding load balancing of a service by Azure Load Balancer. My load balancing requirement is as follows:

1. I will have multiple application servers for a non-http service. Application servers will be behind Azure load balancer(layer 4).
2. A client will initiate a connection to the load balancer and will send multiple requests over this same connection.
3. Load balancer need to distribute the requests from this single client connection to the multiple application servers in the backend.

Does Azure load balancer provide such load balancing?

Answer 1

Hello @Dhirendra Singh ,

Welcome to Microsoft Q&A Platform. Thank you for reaching out & hope you are doing well.

I understand that you would like to know if requests coming from a single client will be load balanced to the multiple application servers in the backend.

Yes, Azure load balancer will load balance the requests coming from a single client to the multiple application servers in the backend.

Azure Load Balancer uses a five-tuple hashing algorithm for the distribution of inbound flows (not bytes). Load balancer rewrites the headers of TCP/UDP headers flows when directing traffic to the backend pool instances (load balancer doesn't rewrite HTTP/HTTPS headers). When the load balancer's health probe indicates a healthy backend endpoint, backend instances are available to receive new traffic flows.

By default, Azure Load Balancer uses a five-tuple hash.

The hash is used to route traffic to healthy backend instances within the backend pool. The algorithm provides stickiness only within a transport session. When the client starts a new session from the same source IP, the source port changes and causes the traffic to go to a different backend instance. In order to configure hash-based distribution, you must select session persistence to be None in the Azure portal. This specifies that successive requests from the same client may be handled by any virtual machine in the backend.

Refer: https://learn.microsoft.com/en-us/azure/load-balancer/concepts

https://learn.microsoft.com/en-us/azure/load-balancer/distribution-mode-concepts

Kindly let us know if the above helps or you need further assistance on this issue.

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