Ipv4/Ipv6 Over Ipv6 Tunnel - 3Com MSR 50 Series Configuration Manual

698 C 49: T
HAPTER UNNELING
IPv4/IPv6 over IPv6
Tunnel
C
ONFIGURATION
Encapsulation and decapsulation
Packets to be transferred through a tunnel undergo an encapsulation process and
decapsulation process.
Figure 208 Principle of IPv4 over IPv4 tunnel
IPv 4 header IPv4 data
IPv4 network
IPv 4 host
Encapsulation
■
The encapsulation process is as follows:
1 The interface of Router A connecting to an IPv4 host receives an IP packet and
submits it to the IP protocol stack for processing.
2 The IP protocol stack determines how to route the packet according to the
destination address in the IP header. If the destination of the packet the IPv4 host
connected to Router B, the packet is sent to Router A's tunnel interface that is
connected to Router B.
3 After the tunnel interface receives the packet, the packet is encapsulated and
submitted to the IP protocol stack for processing. The IP protocol stack determines
the outgoing interface of the tunnel according to the IP header.
Decapsulation
■
Contrary to the encapsulation process, the decapsulation process is as follows:
1 The IP packet received from the IPv4 network interface is sent to the IP protocol
stack which checks the protocol number in the IP header.
2 If the protocol number is IPv4, the IP packet is sent to the tunnel module for
decapsulation
3 The decapsulated IP packet is sent back to the IP protocol stack for processing.
Introduction to IPv4/IPv6 over IPv6 tunneling protocol
IPv4/IPv6 over IPv6 tunneling protocol (RF2473) is developed for IPv4 or IPv6 data
packet encapsulation so that encapsulated packets can be transmitted over an
IPv6 network. The encapsulated packets are IPv6 tunnel packets.
Figure 208 shows these two processes.
IPv 4 header IPv 4 header IPv4 data
IPv 4 network
IPv4 tunnel
Router A
IPv4 header IPv 4 data
IPv 4 network
Router B
IPv 4 host