NAT Gateway Specifications

Updated on 2023-08-02 GMT+08:00

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The NAT gateway performance is determined by the maximum number of SNAT connections supported.

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

NOTE:

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.

**Table 2** Private NAT gateway specifications
Specifications	Maximum Number of SNAT Connections	Bandwidth	PPS	Number of NAT Rules (SNAT Rules+DNAT Rules)
Small	2,000	200 Mbit/s	20,000	20
Medium	5,000	500 Mbit/s	50,000	50
Large	20,000	2 Gbit/s	200,000	200
Extra-large	50,000	5 Gbit/s	500,000	500

NOTE:

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.

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