Technical data

10 ServerIron ADX NAT64 Configuration Guide

53-1002288-02

Operation of NAT64 for IPv6-only client to IPv4 resource

DRAFT: BROCADE CONFIDENTIAL

The DNS64 server (not supplied by Brocade) is configured to respond to a query from the IPv6

client with an IPv6 address created from the NAT64 prefix and the IPv4 address of the IPv4-only

server. In the example shown in Figure 3, the IPv6 client sends a query to the DNS64 server for the

IP address of “www.brocadetest.com” and the DNS server responds with the IPv6 address

“2001:db8::100.1.1.1”. Notice that this address is made up of the NAT64 prefix (2001:db8::) and

the IP address of the IPv4-only server (100.1.1.1).

FIGURE 3 IPv6 client to DNS server communication

Figure 4 illustrates the stateful NAT64 translation. In this example, the packet is sent with the IPv6

source address of the client (2001:dba:ccc::1) to the destination IPv6 address that was obtained

for “brocadetest.com” (2001:db8::100.1.1.1) from the DNS64 server. The NAT64 gateway then

selects the IP address “192.0.2.1” from the assigned pool (192.0.2.1 - 192.0.2.10) as its source

IPv4 address. It strips the IPv6 prefix from the destination IPv6 address that was sent from the

IPv6-only client and sets the remaining IPv4 address (100.1.1.1) as the new destination address.

Because NAT64 is stateful, the NAT64 gateway keeps track of all its connections. When a return

packet from the IPv4 server destined for the IPv6-only client arrives at the NAT64 gateway, it is able

to map the packet with the destination address “192.0.2.1” (from the pool) to the client’s IPv6

address (2001:dba:ccc::11), and the IPv4-only server’s source address (100.1.1.1) back to the

IPv6 prefixed address.

FIGURE 4 Stateful NAT64 translation

NOTE

If the ServerIron ADX receives an IPv6 packet that contains a protocol other than TCP, UDP, or

ICMPv6 in the last Next Header, then the packet should be discarded silently

DNS Server

IPv6 Client

IPv6

www.brocadetest.com

2001:db8::100.1.1.1

Stateful NAT64 translation

IPv6-only Client

IPv6 address = 2001:dba:ccc::1

IPv4-only Server

IPv4 address = 100.1.1.1

ServerIron ADX

with NAT64

Source IP =2001:dba:ccc::1

Destination IP = 2001:db8::100.1.1.1

Source IP = 192.0.2.1

Destination IP = 100.1.1.1

Source IP = 2001:db8::100.1.1.1

Destination IP = 2001:dba:ccc::1

Source IP = 100.1.1.1

Destination IP = 192.0.2.1