tunnel ipv4-ipv6(system view)

Usage Scenario

An IPv6 tunnel packet can be encapsulated and carried as payload within an IPv6 packet of another tunnel, which is called IPv6 nested encapsulation. Nested encapsulation occurs when an intermediate node of an IPv6 tunnel is an ingress node of another IPv6 tunnel. If an IPv6 packet undergoes excessive nested encapsulations, the packet will be oversized and discarded. Therefore, when a Huawei device interworks with devices of other vendors, run the tunnel ipv4-ipv6 encapsulation-limit command to configure the maximum number of IPv6 encapsulations that can be performed on embedded tunnel nodes. You are advised to set the encapsulation-limit parameter to a value that is not larger than 4.

To allow a device to recognize and provide special processing for packets in a flow, run the tunnel ipv4-ipv6 flow-label command to mark the packets of a specific service flow.

To rapidly terminate packet transmission when routing loops occur on an IPv4 over IPv6 tunnel, run the tunnel ipv4-ipv6 hop-limit command to set a hop limit for IPv6 packets. To allow IPv6 tunnel packets to reach the egress of the tunnel, you need to set the hop limit based on the actual network topology.

The traffic class value of IPv4 over IPv6 tunnel packets refers to the value that a tunnel ingress node sets in the Traffic Class field of a tunnel header to identify the service types of IPv6 packets. The Traffic Class field functions in the same way as the ToS field in IPv4 packets. To set the traffic class value for an IPv4 over IPv6 tunnel, run the tunnel ipv4-ipv6 traffic-class command.

Prerequisites

The tunnel encapsulation mode has been set to IPv4 over IPv6 using the tunnel-protocol ipv4-ipv6 command.

Precautions

An IPv6 tunnel packet can be encapsulated and carried as payload within an IPv6 packet of another tunnel, which is called IPv6 nested encapsulation. Nested encapsulation occurs when an intermediate node of an IPv6 tunnel is an ingress node of another IPv6 tunnel.

If an IPv6 packet undergoes excessive nested encapsulations, the packet will be oversized and discarded.

Therefore, when a Huawei device interworks with devices of other vendors, run the tunnel ipv4-ipv6 encapsulation-limit command to configure the maximum number of IPv6 encapsulations that can be performed on embedded tunnel nodes. You are advised to set the encapsulation-limit parameter to a value that is not larger than 4.