Azure Auto Scaling works but load doesn´t get distributed

Question

i have a problem with auto scaling in azure. The scaling process works fine but when a new instance is added it becomes no traffic.

My scenario:

I have 2 running instances whit a WCF webservice on it. Now i shot from 2 other servers(not azure) data to the webservice. After a while the auto scaling kicks in and a new instance is added. The 2 servers are producing still load on the first 2 azure servers. However the new one doesn´t get any.

I thought azure is using round robin for load balancing or am i missing sth. else?

Thx for any help.

Answer 1

The problem is because of TCP connection keep-alive - when the clients first connect the connection is established to existing instances and then it persists to those instances. So when the service scales out the clients won't reconnect unless the connection is broken. New clients will connect to both existing and new instances.

Here's another question for a very similar scenario. For testing purposes you can just disable keep-alive to ensure that load is indeed distributed between instances.