Does Subscriptions Have a Backplane to Support Multiple Servers

I've tried subscriptions and it works in a single server scenario. How can I make it work when you have multiple load balanced servers? Signal-R uses a concept called a backplane which is basically a data store where a list of subscribers are stored.

Ideally there would be a simple interface I can implement to add, get or delete subscriptions. I could then implement the interface and store the subcriptions in Redis for example.

The closest thing I can find is the `ISubscriptionManager` but that seems to also mix the concepts of storing subscriptions and executing operations.