H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 287)

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select the same IP address from their address pool and assign the same port number, reverse sessions on
the two devices are the same. As a result, they cannot back up session data.
To solve the problem, the low-priority address pool attribute is introduced to NAT. Configure a
non-low-priority address pool on a device and configure a low-priority address pool on the other device.
The two address pools have the same address range, but have different port number ranges so that the
devices can back up session data.
For more information about stateful failover, see "
Configuring stateful failover ."
Configuration guidelines
When you configure address pools, follow these guidelines:
• On certain types of devices, an address pool cannot include IP addresses in other address pools,
IP addresses of interfaces with Easy IP enabled, or public IP addresses of internal servers.
• Low-priority address pools cannot include IP addresses in non low-priority address pools, external
IP addresses for one-to-one NAT, and public IP addresses of internal servers.
• The address pool, dynamic NAT, static NAT, and internal server configurations can be modified
through Web pages. The modification you make takes effect after the former configuration is
removed by the system.
Recommended configuration procedure
Configuring address translation
A NAT device can be configured with or dynamically generate mapping entries to translate between
internal and external network addresses. Address translation can be classified into dynamic and static
NAT.
Dynamic NAT
A dynamic NAT entry is generated dynamically. Dynamic NAT is implemented by associating an ACL
with an address pool (or the address of an interface in the case of Easy IP). This association defines what
packets can use the addresses in the address pool (or the interface's address) to access the external
network. Dynamic NAT is applicable when a large number of internal users must access external
networks. An IP address is selected from the associated address pool to translate an outgoing packet.
After the session terminates, the selected IP address is released.
Table 96 Dynamic NAT configuration task list
Task Remarks
Creating an address pool Required for configuring NAPT and many-to-many NAT.
Configuring dynamic NAT
Required.
Configure dynamic NAT on an interface.
Static NAT
Mappings between external and internal network addresses are manually configured. Static NAT can
meet fixed access requirements of a few users.