Ipv6 Transition Technologies; Dual Stack; Tunneling - HP FlexNetwork MSR2003 Configuration Manual

Figure 84 Path MTU discovery process
1. The source host sends a packet no larger than its MTU to the destination host.
2. If the MTU of a device's output interface is smaller than the packet, the device performs the
following tasks:
Discards the packet.
Returns an ICMPv6 error message containing the interface MTU to the source host.
3. Upon receiving the ICMPv6 error message, the source host performs the following tasks:
Uses the returned MTU to limit the packet size.
Performs fragmentation.
Sends the fragments to the destination host.
4. Step 2 and step 3 are repeated until the destination host receives the packet. In this way, the
source host finds the minimum MTU of all links in the path to the destination host.

IPv6 transition technologies

IPv6 transition technologies enable communication between IPv4 and IPv6 networks. The following
IPv6 transition technologies can be used for different applications:
•
Dual stack (RFC 2893)
•
Tunneling (RFC 2893)
•
NAT-PT (RFC 2766)
•
IPv6 on the provider edge routers (6PE)

Dual stack

Dual stack is the most direct transition approach. A network node that supports both IPv4 and IPv6 is
a dual-stack node. A dual-stack node configured with an IPv4 address and an IPv6 address can
forward both IPv4 and IPv6 packets. An application that supports both IPv4 and IPv6 prefers IPv6 at
the network layer.
Dual stack is suitable for communication between IPv4 nodes or between IPv6 nodes. It is the basis
of all transition technologies. However, it does not solve the IPv4 address depletion issue because
each dual-stack node must have a globally unique IPv4 address.

Tunneling

Tunneling uses one network protocol to encapsulate the packets of another network protocol and
transfers them over the network. For more information about tunneling, see
208
"Configuring tunneling."