HP-UX IPv6 Porting Guide (February 2007)

Overview of IPv4 and IPv6 Call Set-up
Using AF_INET6 Socket to Receive IPv4 Communications
Chapter 5 23
Using AF_INET6 Socket to Receive IPv4 Communications
An IPv6 application using an AF_INET6 socket can accept TCP connection requests from a
remote IPv4 application. The example below is contrived to demonstrate an incoming IPv4
packet destined for an application’s IPv6 socket.
In this overview diagram, an incoming IPv4 packet requests connection to an IPv6 socket.
IPv6 internally creates an IPv4-mapped IPv6 address, accepts the connection, and looks up
the host name of the requesting node.
Figure 5-3
1. An IPv4 packet arrives at an Ethernet port.
2. The Ethernet driver examines the
type field in the Ethernet packet.
86DD
type is an IPv6 packet
0800
type is an IPv4 packet