Overview
The Elastic Network Interface (ENI) is a flexible networking interface that connects Cloud Virtual Machine (CVM) instances within a Virtual Private Cloud (VPC), facilitating smooth migration across multiple CVM instances. It supports the binding of multiple ENIs to a single CVM instance to establish a robust and available network. Furthermore, it allows for the assignment of multiple private IP addresses to a single ENI, enabling deployment scenarios with multiple IPs on a single server.
Benefits
Elasticity
ENI facilitates seamless migration between CVM servers, enabling the establishment of a cost-effective, highly available solution. As an illustration, a single ENI can serve as the network interface for vital services. In the event of a failure of the CVM instance hosting these services, its ENI can swiftly connect to another pre-configured, operational instance, ensuring rapid service restoration.
High Reliability
ENI facilitates the implementation of high-reliability cluster deployments by leveraging multiple network interfaces. This architecture emphasizes the necessity of ensuring system availability through multi-server hot backup for critical components. Utilizing ENI alongside private IPs, which offer flexible binding and unbinding capabilities, enables the configuration of a Keepalived-based disaster recovery solution, thereby ensuring the robust reliability of pivotal system elements.
Security
ENI facilitates the establishment of numerous security protocols within the network. Through this, one ENI can manage external communications by implementing a security group policy to regulate access from the Internet to the server. Meanwhile, another ENI can oversee internal communications by being assigned multiple IPs from various VPC subnets, enabling the configuration of distinct security group policies for these subnets to establish a management network.
Isolation
The CVM server can be outfitted with multiple ENIs across different subnets, with each subnet possessing unique network routes to efficiently separate public and private network traffic.
Flexibility
A single CVM server can be equipped with multiple ENIs, each supporting several private IPs. For instance, a mid-layer web server can leverage multiple ENIs to establish a dual-host solution. In the event of instance failure, primary and secondary IP addresses can be assigned to ENIs to facilitate swift migration.
Features
Multi-network Interface Support
In addition to the primary ENI automatically generated upon the creation of a CVM server, it is possible to attach multiple auxiliary ENIs to the CVM server. These additional ENIs may originate from various subnets within the same VPC or availability zone. Each auxiliary ENI allows for the setup of distinct security group configurations and separate routing settings.
Flexible Migration
ENI migration among CVM servers within the same VPC or availability zone is seamlessly facilitated, without any charges. Upon detachment from a server, ENI retains its private IP, elastic public IP, and security group policy, eliminating the necessity for re-association post-migration.
Multi-IP Support
Depending on the specifications of the CVM server, an ENI can be associated with a maximum of 30 private IPs, each of which can additionally be linked with individual elastic public IPs. A single server has the capability to open multiple identical ports via various elastic public IPs. The correlation between the ENI and the private IPs facilitates this functionality.
Independent Routing and Forwarding
A single CVM server has the capability to be associated with multiple ENIs across various subnets within the same VPC or availability zone. This enables the configuration of distinct routing and forwarding policies for each subnet, facilitating network isolation. It’s possible to establish routing policies for the server to direct specified network traffic accordingly.
Scenarios
Network Isolation
High-reliability Application Deployment
The network deployment of critical businesses often necessitates the segregation of private, public, and administrative networks to uphold data security and network isolation. This can be achieved through various routing and security group policies. By configuring three auxiliary ENIs on distinct subnets for a server within the VPC, isolation objectives can be met effectively. These subnets serve designated purposes: data transfer on the private network, service provision on the public network, and administrative tasks within the private network.
Each ENI can be associated with unique security group policies to enable differentiated security controls across different networks, thereby safeguarding both the server and the private network. Moreover, individual subnets can be equipped with distinct routing tables, allowing each ENI to adhere to its own routing policy. For instance, directing the route of the data transfer subnet towards private traffic sources such as Direct Connect gateway, VPN gateway, or VPC Peering Connection, while routing the subnet containing the public ENI towards public traffic sources like NAT gateway or public gateway, facilitates effective isolation between the private and public networks.
Furthermore, implementing different network ACL policies for the private, public, and management networks enables the enforcement of a comprehensive three-layer security policy across subnets.
The system architecture’s essential elements must ensure elevated system availability through multi-server hot backup. Cloud services offer ENI and private IPs with adaptable binding and unbinding capabilities, facilitating the configuration of a disaster recovery solution based on Keepalived to achieve optimal availability for critical components.
- Procuring two or more CVM servers within the same subnet or across different subnets within the same availability zone serves as disaster recovery units for the critical components.
- Leveraging CVM’s Keepalived notification mechanism enables API-based IP scheduling across multiple CVM servers, ensuring heightened availability across multiple servers.
- ENI’s flexible migration capabilities can be utilized to transfer the faulty CVM server’s ENI to the backup server, facilitating cluster-based disaster recovery.
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