[rdli]

Istio is focused on service-to-service traffic (i.e., in your data center). It uses Lyft Envoy's L7 proxy to add security, resilience, and observability to your L7 traffic.

Imagine you've got 50 microservices and you're using RPC to communicate. You're going to want global rate limiting and circuit breaking behavior to insure resilience, particularly as your topology gets deeper.

There is a use case for extending Istio to the Edge, which is why we wrote Ambassador (it's an API Gateway built on Envoy), and we just released an Istio integration (http://www.getambassador.io/user-guide/with-istio.html).

Full disclosure: Work on Ambassador