Note_Tech

All technological notes.

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Kubernetes Networking: Topology-Aware Routing (TAR)

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• Kubernetes Networking: Topology-Aware Routing (TAR)
  • Configuring Services to route traffic to nearby endpoints
  • Topology-Aware Routing (TAR)

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Configuring Services to route traffic to nearby endpoints

• When you deploy pods, they are distributed across the nodes in the cluster.

  • If cluster nodes span different availability zones or regions and the pods deployed on those nodes exchange traffic with each other, network performance and traffic costs can become an issue.
  • In this case, it makes sense for services to forward traffic to pods that aren’t far from the pod where the traffic originates.

• svc.spec.internalTrafficPolicy field

  • local:
    • traffic from pods on a given node is forwarded only to pods on the same node.
    • If there are no node-local service endpoints, the connection fails.

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Topology-Aware Routing (TAR)

• Topology-Aware Routing (TAR)

  • intelligently directs network traffic to stay within the same physical zone (like an AWS Availability Zone) where it started, reducing latency, cutting cloud provider costs for cross-zone data transfer, and improving performance by keeping communication local
• all cluster nodes must contain the kubernetes.io/zone label to indicate which zone each node is located in.

• service.kubernetes.io/topology-aware-hints=auto

  • adds the hints to each endpoint in the EndpointSlice object(s)
• Example:

apiVersion: discovery.k8s.io/v1
kind: EndpointSlice
metadata:
  name: example-hints
  labels:
    kubernetes.io/service-name: example-svc
addressType: IPv4
ports:
  - name: http
    protocol: TCP
    port: 80
endpoints:
  - addresses:
      - "10.1.2.3"
    conditions:
      ready: true
    hostname: pod-1
    zone: zone-a
    hints: # hint
      forZones:
        - name: "zone-a"

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