Selecting a Network Model

CCE uses proprietary, high-performance container networking add-ons to support the tunnel network and VPC network models.

After a cluster is created, the network model cannot be changed. Exercise caution when selecting a network model.

Tunnel network: The container network is an overlay tunnel network on top of a VPC network and uses the VXLAN technology. This network model is applicable when there is no high requirements on performance. VXLAN encapsulates Ethernet packets as UDP packets for tunnel transmission. Though at some cost of performance, the tunnel encapsulation enables higher interoperability and compatibility with advanced features (such as network policy-based isolation), meeting the requirements of most applications.
Figure 1 Container tunnel network
VPC network: The container network uses VPC routing to integrate with the underlying network. This network model is applicable to performance-intensive scenarios. The maximum number of nodes allowed in a cluster depends on the route quota in a VPC network. Each node is assigned a CIDR block of a fixed size. VPC networks are free from tunnel encapsulation overhead and outperform container tunnel networks. In addition, as VPC routing includes routes to node IP addresses and container network segment, container pods in the cluster can be directly accessed from outside the cluster.
Figure 2 VPC network

The following table lists the differences between the network models.

**Table 1** Network model comparison
Dimension	Tunnel Network	VPC Network
Application scenarios	Common container service scenarios Scenarios that do not have high requirements on network latency and bandwidth	Scenarios that have high requirements on network latency and bandwidth Containers can communicate with VMs using a microservice registration framework, such as Dubbo and CSE.
Core technology	OVS	IPvlan and VPC route
Applicable clusters	CCE standard cluster	CCE standard cluster
Network isolation	Kubernetes native NetworkPolicy for pods	No
Passthrough networking	No	No
IP address management	The container CIDR block is allocated separately. CIDR blocks are divided by node and can be dynamically allocated (CIDR blocks can be dynamically added after being allocated.)	The container CIDR block is allocated separately. CIDR blocks are divided by node and statically allocated (the CIDR block cannot be changed after a node is created).
Network performance	Performance loss due to VXLAN encapsulation	No tunnel encapsulation. Cross-node packets are forwarded through VPC routers, delivering performance equivalent to that of the host network.
Networking scale	A maximum of 2000 nodes are supported.	Suitable for small- and medium-scale networks due to the limitation on VPC routing tables. It is recommended that the number of nodes be less than or equal to 1000. Each time a node is added to the cluster, a route is added to the VPC routing tables. Therefore, the cluster scale is limited by the VPC routing tables.

The scale of a cluster that uses the VPC network model is limited by the custom routes of the VPC. Therefore, you need to estimate the number of required nodes before creating a cluster.
By default, VPC routing network supports direct communication between containers and hosts in the same VPC. If a peering connection policy is configured between the VPC and another VPC, the containers can directly communicate with hosts on the peer VPC. In addition, in hybrid networking scenarios such as Direct Connect and VPN, communication between containers and hosts on the peer end can also be achieved with proper planning.

Parent topic: Networking