* That may happen later by the connection pool thread.
   */
  fun cancel()

  /**
   * Carries an exchange. This is usually a connection, but it could also be a connect plan for
   * CONNECT tunnels. Note that CONNECT tunnels are significantly less capable than connections.
   */
  interface Carrier {
    val route: Route

    fun trackFailure(
      call: RealCall,
      e: IOException?,
    )

```mermaid
graph TD;
src[src pod]-->|plaintext port|ztunnel{"ztunnel (L4 policy applied here)"}
ztunnel{ztunnel}-->|TLS|wp{waypoint}
wp-->|mTLS|ztunnel
ztunnel-->|plaintext|dst[dst pod]
```

And here's an example of an authenticated request to a captured destination:

```mermaid
graph TD;
src[src pod]-->|15008|ztunnel{ztunnel}
ztunnel-->|HBONE|dwp{"destination waypoint (all policy applied here)"}

    replaceWith = ReplaceWith(expression = "socketAddress"),
    level = DeprecationLevel.ERROR,
  )
  fun socketAddress(): InetSocketAddress = socketAddress

  /**
   * Returns true if this route tunnels HTTPS or HTTP/2 through an HTTP proxy.
   * See [RFC 2817, Section 5.2][rfc_2817].
   *
   * [rfc_2817]: http://www.ietf.org/rfc/rfc2817.txt
   */
  fun requiresTunnel(): Boolean {

  internal var hasFailure: Boolean = false
    private set

  internal val connection: RealConnection
    get() = codec.carrier as? RealConnection ?: error("no connection for CONNECT tunnels")

  internal val isCoalescedConnection: Boolean
    get() = finder.routePlanner.address.url.host != codec.carrier.route.address.url.host

  @Throws(IOException::class)
  fun writeRequestHeaders(request: Request) {

 * Implementations for common types can be found in {@link Funnels}.
 *
 * <p>Note that serialization of {@linkplain BloomFilter bloom filters} requires the proper
 * serialization of funnels. When possible, it is recommended that funnels be implemented as a
 * single-element enum to maintain serialization guarantees. See Effective Java (2nd Edition), Item

1. Immediately upon starting a drain, `ztunnel-old` will close its listeners. Now only `ztunnel-new` is listening. Critically, at all times there was at least one ztunnel listening.
1. While `ztunnel-old` will not accept *new* connections, it will continue processing existing connections.
1. After `drain period` seconds, `ztunnel-old` will forcefully terminate any outstanding connections.

> [!NOTE]

local queries = (import './queries.libsonnet').queries({
  container: "istio-proxy",
  pod: "ztunnel-.*",
  component: "ztunnel",
  app: "ztunnel",
});

dashboard.new('Istio Ztunnel Dashboard')
+ g.dashboard.withPanels(
  grid.makeGrid([
    row.new('Process')
    + row.withPanels([
      panels.timeSeries.base('Ztunnel Versions', queries.istioBuild, 'Version number of each running instance'),

        .addEqualityGroup(Funnels.longFunnel())
        .addEqualityGroup(Funnels.unencodedCharsFunnel())
        .addEqualityGroup(Funnels.stringFunnel(UTF_8))
        .addEqualityGroup(Funnels.stringFunnel(US_ASCII))
        .addEqualityGroup(
            Funnels.sequentialFunnel(Funnels.integerFunnel()),
            SerializableTester.reserialize(Funnels.sequentialFunnel(Funnels.integerFunnel())))

    HashFn hf =
        new HashFn() {
          @Override
          public byte[] hash(byte[] input, int seed) {
            Hasher hasher = murmur3_32(seed).newHasher();
            Funnels.byteArrayFunnel().funnel(input, hasher);
            return hasher.hash().asBytes();
          }
        };
    // Murmur3A, MurmurHash3 for x86, 32-bit (MurmurHash3_x86_32)

//
// 1. Constructs a ztunnel state message to initialize ztunnel
// 2. Syncs the host ipset
func (s *NetServer) ConstructInitialSnapshot(ambientPods []*corev1.Pod) error {
	var consErr []error

	podsByUID := slices.GroupUnique(ambientPods, (*corev1.Pod).GetUID)
	if err := s.buildZtunnelSnapshot(podsByUID); err != nil {
		log.Warnf("failed to construct initial ztunnel snapshot: %v", err)
		consErr = append(consErr, err)