Service Internal Traffic Policy [page]deterministic
If two Pods in your cluster want to communicate, and both Pods are actually running on the same node, use _Service Internal Traffic Policy_ to keep network traffic within that node. Avoiding a round trip via the cluster network can help with reliability, performance (network latency and throughput), or cost.
_Service Internal Traffic Policy_ enables internal traffic restrictions to only route internal traffic to endpoints within the node the traffic originated from. The "internal" traffic here refers to traffic originated from Pods in the current cluster. This can help to reduce costs and improve performance.
## Using Service Internal Traffic Policy
You can enable the internal-only traffic policy for a [Service](#gloss:service), by setting its `.spec.internalTrafficPolicy` to `Local`. This tells kube-proxy to only use node local endpoints for cluster internal traffic.
> Note: For pods on nodes with no endpoints for a given Service, the Service behaves as if it has zero endpoints (for Pods on this node) even if the service does have endpoints on other nodes.
The following example shows what a Service looks like when you set `.spec.internalTrafficPolicy` to `Local`:
```yaml apiVersion: v1 kind: Service metadata: name: my-service spec: selector: app.kubernetes.io/name: MyApp ports: - protocol: TCP port: 80 targetPort: 9376 internalTrafficPolicy: Local ```
## How it works
The kube-proxy filters the endpoints it routes to based on the `spec.internalTrafficPolicy` setting. When it's set to `Local`, only node local endpoints are considered. When it's `Cluster` (the default), or is not set, Kubernetes considers all endpoints.
##
* Read about [Topology Aware Routing](/docs/concepts/services-networking/topology-aware-routing) * Read about [Service External Traffic Policy](/docs/tasks/access-application-cluster/create-external-load-balancer/#preserving-the-client-source-ip) * Follow the [Connecting Applications with Services](/docs/tutorials/services/connect-applications-service/) tutorial