Technical data

30 ServerIron ADX NAT64 Configuration Guide
53-1002288-02
Operation of NAT46 for IPv4-only client to IPv6 resource
3
DRAFT: BROCADE CONFIDENTIAL
DNS Dynamic Learning – If a packet is received at the NAT46 gateway with IPv4 destination
address within the range defined by the NAT64 IPv4 prefix and it does not contain an entry in
its mapping table for that IPv4 address, the gateway will send a PTR query to the DNS64 server
to obtain the hostname of the resource it is trying to reach. The NAT46 gateway then sends a
query for the hostname to determine the corresponding IPv6 address. The mapping defined by
this operation is then entered into the mapping table of the NAT46 gateway.
Pre-fetched DNS Dynamic Learning – Optionally, the NAT46 gateway can be configured
(prefetch option) to periodically send PRT queries to the DNS64 server (as described for
Real-time DNS Query) to determine IPv6 address translations for each of the IPv4 destination
addresses defined IPv4 addresses within the range defined by its IPv4 prefix. The NAT46
gateway uses this information to populate its mapping table.
Operation of NAT46 for IPv4-only client to IPv6 resource
Figure 9 provides a high-level view of the IPv4-only client to IPv6 resource configuration. As shown,
the client only resides in an IPv4 network and the server (resource) only resides in an IPv6 network.
The DNS64 server and the ServerIron ADX (configured as a NAT64 gateway) communicate with
both the IPv4 and IPv6 networks.
The ServerIron ADX configured as a NAT46 gateway has an IPv4-prefix that defines the IPv4
addresses that represent the IPv6 resources that it makes available to IPv4 clients. In this
example, an IPv4 prefix of 100.1.1./32 is configured on the NAT46 gateway. This means that any IP
address within the subnet“100.1.1.x” can be assigned to an IPv6 resource in the IPv6-only
network. In this example, the IPv4 address “100.1.1.1” is assigned by the administrator of the
DNS64 server to the IPv6 resource “brocadetest.com” (IPv6 address 2001:db8::).
The gateway is also configured with an IPv6-prefix that when combined with a client IPv4 address
provides a source IPv6 address on the NAT46 gateway that represents each of the IPv4 clients to
the IPv6 resources. The NAT64 IPv6 prefix defined on this gateway is 2001:11::.
FIGURE 9 IPv6-only client to IPv4 resource overview
The DNS64 server (not supplied by Brocade) is configured to respond to a query from the IPv4
client with an IPv4 address within the subnet defined by the IPv4 prefix. In the example shown in
Figure 10, the IPv4 client sends a query to the DNS64 server for the IPv4 address of the resource
“www.brocadetest.com” and the DNS server responds with the IPv4 address “100.1.1.1”.
IPv6
ServerIron ADX
with NAT46
DNS 64 Server
IPv4-only Client
IPv4
IPv6 + IPv4
NAT64 IPv6 Prex: 2001:db8::
NAT64 IPv4 Prex: 100.1.1./32
IPv6 address:
2001:11::
IPv6-only Server
IPv4 address:
192.0.2.1
IPv6 address: 2001.db8.ddd.1
IPv6 address: 192.168.13.12
IPv4 address:
192.168.13.50