SCTP support in AKO for L4 services

Overview

This feature supports the SCTP protocol in AKO for L4 services, Kubernetes/OpenShift Load Balancer services, and Gateway objects and their corresponding backend services. Prior to version 1.9.1, only TCP and UDP protocols were supported.

For more information on Gateway class and Gateway objects with AKO, see Gateway and Gateway Class.

Starting with version 22.1.3, Avi Controller supports SCTP traffic for L4 virtual services. The Avi Controller has introduced SCTP-specific properties for virtual services and pools. These include System-SCTP-Proxy TCP/UDP (network) profile for supporting SCTP traffic in virtual services, an SCTP-based System-SCTP health monitor for pools, and an SCTP protocol match option in L4 Policy Set match rules.

The user must create a Load Balancer service or a Gateway-based L4 service with SCTP protocol in the port definition. The AKO running in the Kubernetes/OpenShift cluster will consume the service and gateway definitions. AKO will create the corresponding virtual service in Avi Controller with the appropriate System-SCTP-Proxy TCP/UDP (network) profile and the corresponding pools with the appropriate System-SCTP health monitor. The L4PolicySet is also created with appropriate match rules for the SCTP protocol.

Note: SCTP protocol support is not available for service type NodePortLocal, because Antrea CNI does not support SCTP Service ports for NodePortLocal type services.

Configuration

The configuration mainly includes creating Load Balancer services and Gateway objects and their corresponding backend services with SCTP protocol in port definitions.

Following is the configuration sample of Load Balancer service yaml definitions:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: sctp-demo
  labels:
    app: server
spec:
  replicas: 2
  selector:
    matchLabels:
      app: server
  template:
    metadata:
      labels:
        app: server
    spec:
      containers:
      - name: sctp-demo
        image: <sctp enabled container image>
        ports:
        - containerPort: 9090
          protocol: SCTP
---
apiVersion: v1
kind: Service
metadata:
  name: server
  namespace: default
spec:
  ports:
  - port: 80
    protocol: SCTP
    targetPort: 9090
  selector:
    app: server
  type: LoadBalancer

Following is the configuration sample of Gateway objects yaml definitions:

apiVersion: networking.x-k8s.io/v1alpha1
kind: GatewayClass
metadata:
  name: avi-lb
spec:
  controller: ako.vmware.com/avi-lb
  parametersRef:
    group: ako.vmware.com
    kind: AviInfraSetting
    name: my-infrasetting
---
apiVersion: ako.vmware.com/v1alpha1
kind: AviInfraSetting
metadata:
  name: my-infrasetting
---
apiVersion: networking.x-k8s.io/v1alpha1
kind: Gateway
metadata:
  name: my-gateway
  namespace: svcapi
spec:
  gatewayClassName: avi-lb
  listeners:
  - port: 6060
    protocol: SCTP
    routes:
      group: v1
      kind: services
      selector:
        matchLabels:
          ako.vmware.com/gateway-name: my-gateway
          ako.vmware.com/gateway-namespace: svcapi
---
apiVersion: v1
kind: Service
metadata:
  labels:
    ako.vmware.com/gateway-name: my-gateway
    ako.vmware.com/gateway-namespace: svcapi
  name: avisvc-svcapi
  namespace: svcapi
spec:
  ports:
  - name: sixtysixty
    port: 6060
    protocol: SCTP
    targetPort: 9090
  selector:
    app: avi-server
  type: ClusterIP
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: avi-server
  namespace: svcapi
spec:
  replicas: 1
  selector:
    matchLabels:
      app: avi-server
  template:
    metadata:
      labels:
        app: avi-server
    spec:
      containers:
      - image: <sctp enabled container image>
        imagePullPolicy: IfNotPresent
        name: avi-server
        ports:
        - containerPort: 9090
          protocol: SCTP

Note: The above example of Gateway defines a service of type ClusterIP as the backend service. However, you can also use a service of the type NodePort.