Technical data

ServerIron ADX NAT64 Configuration Guide 53
53-1002444-02
Stateless NAT46 dynamic mapping configuration
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The stateless operand is required for stateless NAT46 gateway configurations. Only one IPv6 prefix
can be configured with this option.
Configuring NAT46 IPv4 prefixes with real-time dynamic learning
In a NAT46 configuration, the IPv4 prefix defines the range of IPv4 addresses that can be used to
represent the IPv6 resources available to IPv4 clients.
Use the nat64 ipv4-prefix command to specify an IPv4 prefix with a subnet mask. Any IPv4 address
within the defined subnet can then be assigned to an IPv6 resource made available through the
NAT46 gateway.
Enter a command such as the following:
ServerIron ADX(config)# nat64 ipv4-prefix 200.1.1.0/24
In this example, any IPv4 address within the subnet “200.1.1.x” can be assigned to an IPv6
resource in the IPv6-only network.
Syntax: [no] nat64 ipv4-prefix <prefix/subnet>
The <prefix/subnet> variable specifies the NAT46 IPv4 prefix used by the ServerIron ADX when it
operates as a NAT46 gateway.
Configuring NAT46 real-time dynamic learning
You can configure a ServerIron ADX to perform dynamic learning of IPv4 to IPv6 mappings through
DNS as shown in the following example.
ServerIron ADX(config)# nat64 dns-dynamic-learning
Syntax: [no] nat64 dns-dynamic-learning
With this command configured, a ServerIron ADX will discover IPv6 to IPv4 mappings through DNS
whenever the DNS server receives a new IPv4 destination or IPv6 source. With this command
configured, you can configure a ServerIron ADX to prefetch mappings for IPv4 prefixes using the
nat64 ipv4-prefix <prefix/subnet> prefetch command. For more information, refer to “Configuring
NAT46 IPv4 prefixes with prefetched dynamic learning” on page 54.
You can clear all entries created using dynamic learning as described in “Clearing dynamic
IPv6-IPv4 mappings” on page 57.
Configuring NAT46 hold-off intervals for DNS discoveries
In advanced configurations, you can configure hold-off intervals for DNS discoveries. By default, a
DNS discovery (or refresh) fails if three retries time out or if the DNS64 server returns an error. In
this situation, the NAT46 gateway can still receive traffic intended for IPv6 resources.
Use the nat64 dns-fail-holdoff command to direct the ServerIron ADX to wait a specified period of
time (in seconds) before retrying a request to the DNS64 server. In the following example, the
hold-off interval is set to 300 seconds:
ServerIron ADX(config)# nat64 dns-fail-holdoff 300
Syntax: [no] nat64 dns-fail-holdoff <holdoff-interval>