nt/d/1uM1c3zzoehiijh1ZpZuJ1-SzuVVupenv8r5yuCaFshs/edit#heading=h.dwbqvwmg6ud3))

When a ztunnel receives traffic (authenticated or not) from a workload, it will forward that traffic to the Waypoint proxy **after** applying any `TRANSPORT` layer policies (i.e. `Authorization`s). Thus, if the destination workload has at least the equivalent of a `STRICT` `PeerAuthentication`, unauthenticated traffic will be rejected before it reaches the Waypoint proxy. If the effective policy is `PERMISSIVE`...

![CA Flow](docs/ca.svg)

A single SDS request from Envoy goes through a few different layers in istio-agent.

1. First, the request is handled by the SDS server. This is mostly just an intermediate translation layer exposing
   the `SecretManager` to Envoy, without much business logic. For each resource requested by Envoy, the SDS server
   will call `SecretManager.GenerateSecret(resourceName)`

and aggregate telemetry data. Istio's control plane provides an abstraction
layer over the underlying cluster management platform, such as Kubernetes.

Istio is composed of these components:

- **Envoy** - Sidecar proxies per microservice to handle ingress/egress traffic