Overview

A container network assigns IP addresses to pods in a cluster and provides networking services. In CCE, you can select the following network models for your cluster:

The VPC network model seamlessly combines VPC routing with the underlying network, making it ideal for high-performance scenarios. However, the maximum number of nodes allowed in a cluster is determined by the VPC route quota. This model is suitable for small- and medium-scale networking.
In the VPC network model, container CIDR blocks are separate from node CIDR blocks. To allocate IP addresses to pods running on a node in a cluster, each node in the cluster is allocated with a pod IP range for a fixed number of IP addresses. This network model outperforms the container tunnel network model in terms of performance because it does not have tunnel encapsulation overhead. When the VPC network model is used in a cluster, the routes between container CIDR blocks and VPC CIDR blocks are automatically configured in the VPC route table. This means that pods within the cluster can be accessed directly from cloud servers in the same VPC, even if they are outside the cluster.
The container tunnel network creates a separate network plane for containers by using tunnel encapsulation on the host network plane. This network model uses VXLAN for tunnel encapsulation and Open vSwitch as the virtual switch backend. VXLAN is a protocol that encapsulates Ethernet packets into UDP packets to transmit them through tunnels. Open vSwitch is an open-source virtual switch that provides functions such as network isolation and data forwarding.
While there may be some performance costs, packet encapsulation and tunnel transmission allow for greater interoperability and compatibility with advanced features, such as network policy–based isolation, in most common scenarios.

Network Model Comparison

Table 1 describes the differences of network models supported by CCE.

After a cluster is created, the network model cannot be changed.

**Table 1** Network model comparison
Dimension	Tunnel Network	VPC Network
Application scenarios	Low requirements on performance: As the container tunnel network requires additional VXLAN tunnel encapsulation, it has about 5% to 15% of performance loss when compared with the other two container network models. Therefore, the container tunnel network applies to the scenarios that do not have high performance requirements, such as web applications, and middle-end and back-end services with a small number of access requests. Large-scale networking: Different from the VPC network that is limited by the VPC route quota, the container tunnel network does not have any restriction on the infrastructure. In addition, the container tunnel network controls the broadcast domain to the node level. The container tunnel network supports a maximum of 2000 nodes.	High performance requirements: As no tunnel encapsulation is required, the VPC network model delivers the performance close to that of a VPC network when compared with the container tunnel network model. Therefore, the VPC network model applies to scenarios that have high requirements on performance, such as AI computing and big data computing. Small- and medium-scale networks: Due to the limitation on VPC route tables, it is recommended that the number of nodes in a cluster be less than or equal to 1000.
Core technology	OVS	IPVLAN and VPC route
Applicable clusters	CCE standard cluster	CCE standard cluster
Container network isolation	Kubernetes native NetworkPolicy for pods	No
Interconnecting pods to a load balancer	Interconnected through a NodePort	Interconnected through a NodePort
Managing pod IP addresses	Separate container CIDR blocks are needed. Container CIDR blocks cannot overlap with VPC CIDR blocks. After a cluster is created, the container CIDR block cannot be expanded. To avoid insufficient IP addresses, you are advised to set the subnet mask of the container CIDR block to a maximum of 19 bits.	Separate container CIDR blocks are needed. Container CIDR blocks cannot overlap with VPC CIDR blocks. You can add multiple container CIDR blocks. You can add container CIDR blocks after a cluster is created. For details, see Expanding the Container CIDR Block of a Cluster That Uses a VPC Network. When pod IP addresses are allocated, a fixed IP address range is configured for each node from the container CIDR block. The IP addresses of all pods on a node are allocated from the IP address range.
Maximum number of pods on a node	The value of the kubelet configuration parameter maxPods is used. For details, see Maximum Number of Pods on a Node.	The smaller value between the following two options is used: The value of the kubelet configuration parameter maxPods. For details, see Maximum Number of Pods on a Node. Pod IP addresses reserved for each node. For details, see Number of Allocatable Pod IP Addresses on a Node.
Network performance	Performance loss due to VXLAN encapsulation	No tunnel encapsulation, and cross-node traffic forwarded through VPC routers (The performance is so good that is comparable to that of the host network, but there is a loss caused by NAT.)
Networking scale	A maximum of 2,000 nodes are supported.	Suitable for small- and medium-scale networks due to the limitation on VPC route tables. It is recommended that the number of nodes be less than or equal to 1,000. Each time a node is added to the cluster, a route is added to the VPC route tables. Evaluate the cluster scale that is limited by the VPC route tables before creating the cluster.