ACK Edge supports two container network plugins: Flannel and Terway Edge. You must choose a plugin before you create the cluster; the plugin cannot be changed after cluster creation. This topic compares the two options.
Networking models
The networking model determines how pods communicate with your infrastructure.
Overlay (Flannel): Pods run in a logically separate network encapsulated over the physical network. External clients cannot reach pod IPs directly. VXLAN encapsulation adds minor performance overhead.
Underlay (Terway Edge): Pods share the same network plane as compute resources. External clients can reach pod IPs directly, with no encapsulation overhead. In the cloud, Terway Edge integrates natively with Alibaba Cloud load balancers and Elastic Container Instance (ECI).
Choose a network plugin
| Terway Edge | Flannel VXLAN | |
|---|---|---|
| Plugin source | Developed by Alibaba Cloud | Community plugin (Flannel project) |
| Networking model | Underlay | Overlay |
| Choose when | You manage self-managed data centers or ENS instances; you need large-scale clusters, high network efficiency, or seamless cloud product integration | You manage edge devices or compute instances from other cloud providers; you have small-scale or geographically dispersed deployments |
| Network performance | High — ~20% faster than VXLAN encapsulation | Moderate — VXLAN encapsulation overhead |
| Pod CIDR block | In the cloud: scalable, or use a Virtual Private Cloud (VPC) CIDR block directly. At the edge: fixed at cluster creation | Fixed at cluster creation |
| Integration with cloud products | Full integration with Classic Load Balancer (CLB), Application Load Balancer (ALB), Network Load Balancer (NLB), and ECI | Limited — some features unavailable |
| External access to pod IPs | Supported — external clients can access pod IPs directly | Not supported |
| Limitations for cross-LAN communication | Requires a leased line connecting nodes to the cloud VPC and node vSwitches that support BGP route advertisement | Requires Layer 3 connectivity between nodes |