In APIM we need to have a key that a client knows about: ocp-apim-subscription-key
What happens when traffic manager round robins to another server? Does the client need to know about the second subscription key?
Similar to Azure Traffic Manager and OAuth 2.0 , since Azure Traffic Manager operates at the DNS level, it is not a part of the client-server communication. Any authentication and key handoffs are transparent to Traffic Manager.
Please refer to https://azure.microsoft.com/en-us/documentation/articles/traffic-manager-how-traffic-manager-works/#how-clients-connect-using-traffic-manager for more details