Network

You can configure a default security group and secondary CIDR block for your clusters.

Cluster Network

**Table 1** Parameters
Parameter	Description
VPC	VPC where a cluster resides VPC enables you to provision logically isolated, configurable, manageable virtual networks for cloud servers, cloud containers, and cloud databases. The VPC gives you complete control over your virtual network, allowing you to select your own IP address range, create subnets, configure security groups, and even assign EIPs and allocate bandwidth in your network, enabling secure and easy access to your business system.
VPC CIDR Block	VPC CIDR Block of a cluster
Default Node Subnet	Node subnet of a cluster A subnet is a network that manages ECS network planes. It supports IP address management and DNS. ECSs in a subnet are assigned with its IP addresses. By default, ECSs in all subnets of the same VPC can communicate with one another, but ECSs in different VPCs cannot. You can create a VPC peering connection to enable ECSs in different VPCs to communicate with each other.
Default Node Subnet \| IPv4 CIDR Block	Node subnet CIDR block of a cluster
Network Model	Network model of a cluster After a cluster is created, its network model cannot be changed.
Retain the non-spoofed CIDR block of the original pod IP address. (available only in clusters using the VPC network model)	In a cluster using a VPC network, 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 are regarded as private CIDR blocks of the cluster by default. If the VPC to which the cluster resides uses a secondary CIDR block, operations such as creating or resetting a node will also add the secondary CIDR block to the private CIDR blocks. If a pod tries to access a private CIDR block, the source node will not perform NAT on the pod IP address. Instead, the upper-layer VPC can directly send the pod data packet to the destination, which means, the pod IP address is directly used to communicate with the private CIDR block in the cluster. This function is available only in clusters of v1.23.14-r0, v1.25.9-r0, v1.27.6-r0, v1.28.4-r0, or later versions. NOTE: To enable a node to access a pod in another node, the node CIDR block must be added to this parameter. Similarly, to enable an ECS to access the IP address of a pod in a cluster that is in the same VPC as the ECS, the ECS CIDR block must be added to this parameter.

Service Settings

**Table 2** Parameters
Parameter	Description
Request Forwarding	Forwarding mode of a cluster After a cluster is created, the service forwarding mode cannot be changed. IPVS and iptables are supported. For details, see Comparing iptables and IPVS.
Service CIDR Block	Each Service in a cluster has its own IP address. When creating a CCE cluster, you can specify the Service CIDR block. The Service CIDR block cannot overlap with the subnet or the container CIDR block. The Service CIDR block can be used only within a cluster.
Service Port Range	NodePort port range The default port range is 30000 to 32767. The port range can be changed to 20106 to 32767. After changing the value, go to the security group page and change the TCP/UDP port range of node security groups 30000 to 32767. Otherwise, ports other than the default port cannot be accessed from external networks. NOTE: If the port number is smaller than 20106, a conflict may occur between the port and the system health check port, which may further lead to unavailable cluster. If the port number is greater than 32767, a conflict may occur between the port and the random port of the OS, which may further affect the performance.

Container CIDR Blocks (Available only in Clusters Using the VPC Network Model)

If a container CIDR block configured during cluster creation cannot meet service expansion requirements, you can add more container CIDR blocks. For details, see Adding a Container CIDR Block for a Cluster.