In our experience and testing, these types force us to represent data in inefficient ways because they are general purpose.
Ztunnel is not general purpose; it has an extremely tight goal.
We can exploit this to make a more efficient protocol, which is critical to achieve our resource footprint goals.

For example, configuring Istio mTLS in Envoy takes roughly 50 lines of JSON (it is in Protobuf, of course, but still relevant).

#### Endpoints

Endpoints have an optimized code path, as they are by far the most frequently updated resource - in a steady cluster, this will often be the *only* change, caused by scale up/down.

  // +optional
  optional GroupVersionForDiscovery preferredVersion = 3;

  // a map of client CIDR to server address that is serving this group.
  // This is to help clients reach servers in the most network-efficient way possible.
  // Clients can use the appropriate server address as per the CIDR that they match.
  // In case of multiple matches, clients should use the longest matching CIDR.

</a>

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Istio is an open source service mesh that layers transparently onto existing distributed applications. Istio’s powerful features provide a uniform and more efficient way to secure, connect, and monitor services. Istio is the path to load balancing, service-to-service authentication, and monitoring – with few or no service code changes.