NAT Gateway is a service that supports IP address translation and provides SNAT (Source Network Address Translation) and DNAT (Destination Network Address Translation) capabilities, which can provide secure and high-performance internet access services for resources within a VPC. NAT Gateway supports up to 99.99% high availability, 5Gbps bandwidth, and more than 10 million concurrent connections. Its typical use cases are as follows:
NAT Gateway supports:
- High availability: up to 99.99%
- Bandwidth: 5 Gbps
- Concurrent connections: more than 10 million
Typical Application Scenarios
- Large bandwidth public network egress: For services such as web crawlers and accessing Internet public services.
- Secure public network egress: When a CVM needs to communicate with the Internet but should not be assigned a public IP for security reasons.
Network Topology
When resources in a VPC (e.g., CVMs) send outbound data packets through the NAT Gateway:
- Packets first travel through the router.
- They are then routed according to the routing policy.
- The NAT Gateway sends the traffic to the Internet using the bound EIP as the source IP.
NAT Gateway vs. Public Gateway
CVMs in a VPC can access the Internet through either a NAT Gateway or a Public Gateway. The differences are summarized below:
| Attribute | NAT Gateway | Public Gateway |
|---|---|---|
| Availability | Master/Slave hot backup with automatic failover | Manual switching required for failure |
| Public network bandwidth | Up to 5 Gbps | Depends on CVM network bandwidth |
| Public IP address | Up to 10 EIPs can be bound | Supports one EIP or ordinary public IP |
| Rate limit | 5 Gbps (up to 50 Gbps with support request) | Depends on CVM |
| Max concurrent connections | 10,000,000 | 500,000 |
| Private IP usage | VPC private IPs are not consumed | Subnet private IPs are consumed |
| Security group support | Cannot bind directly; bind to backend CVM instead | Binding supported |
| Network ACL support | Cannot bind directly; bind to subnet of backend CVM | Cannot bind directly; bind to subnet of public gateway |
| Fees | Philippines: • Small (up to 1M connections): $0.09/hr • Medium (up to 3M connections): $0.27/hr • Large (up to 10M connections): $0.89/hr |
Only CVM fees apply; no extra gateway fee |
Advantages of NAT Gateway
Large Capacity
Supports up to 10 million concurrent connections, 5 Gbps bandwidth, and 10 EIPs — ideal for large-scale operations.High Availability
Automatic failover ensures disaster recovery and 99.99% service availability, superior to manual public gateway switching.Cost Effectiveness
Three configurations (small, medium, large) allow flexible billing and high cost-efficiency.