NAT Gateway Specifications

Public NAT Gateway

An SNAT connection consists of a source IP address, source port, destination IP address, destination port, and a transport layer protocol. The source IP address is the EIP, and the source port is the EIP port. An SNAT connection uniquely identifies a session.

Throughput is the total bandwidth of all EIPs in DNAT rules. For example, a public NAT gateway has two DNAT rules. The EIP bandwidth in the first DNAT rule is 10 Mbit/s, and that in the second DNAT rule is 5 Mbit/s. The throughput of the public NAT gateway will be 15 Mbit/s.

A public NAT gateway supports up to 20 Gbit/s of bandwidth.

The default timeout period of an SNAT connection over TCP is 900 seconds.

The default timeout period of an SNAT connection over UDP is 300 seconds.

Select a public NAT gateway based on your service requirements. Table 1 lists the public NAT gateway specifications.

Table 1 Public NAT gateway specifications

Specifications	Maximum Number of SNAT Connections	Bandwidth	Packets per Second (PPS)
Small	10,000	20 Gbit/s	2,000,000
Medium	50,000	20 Gbit/s	2,000,000
Large	200,000	20 Gbit/s	2,000,000
Extra-large	1,000,000	20 Gbit/s	2,000,000

• The PPS of different NAT gateway specifications is the total PPS in both inbound and outbound directions.
• If the number of requests exceeds the maximum allowed connections of a public NAT gateway, services will be adversely affected. To avoid this situation, create alarm rules on the Cloud Eye console to monitor the number of SNAT connections.
• The DNAT rules of a public NAT gateway are irrelevant to the NAT gateway specifications. Up to 200 DNAT rules can be added to a public NAT gateway.

Private NAT Gateway

An SNAT connection consists of a source IP address, source port, destination IP address, destination port, and a transport layer protocol. The source IP address is the transit IP address, and the source port is the port of the transit IP address.

Select a private NAT gateway based on your service requirements. Table 2 lists the private NAT gateway specifications.

If the number of requests exceeds the maximum allowed connections of a private NAT gateway, services will be adversely affected. To avoid this situation, create alarm rules on the Cloud Eye console to monitor the number of SNAT connections.