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Configure IPv6 Features


Configure IPv6 Duplicate Address Detection Attempts

To set the number of attempts the device makes to detect IPv6 duplicate addresses, use the ipv6-duplicate-addr-detection-transmits statement at the [edit system internet-options] hierarchy level:

Accept IPv6 Packets with a Zero Hop Limit

By default, incoming IPv6 packets that have a zero hop limit value in their header are rejected both when they are addressed to the local host and when they are transiting the device. To accept zero hop-limit packets addressed to the local host, include the no-ipv6-reject-zero-hop-limit statement at the [edit system internet-options] hierarchy level. Transit packets are still dropped.

To re-enable rejection of these packets, use the following statement:

Process IPv4-mapped IPv6 Addresses

By default, the Junos OS disables the processing of IPv4-mapped IPv6 packets to protect against malicious packets from entering the network. You may want to enable IPv4-mapped IPv6 packets:

  • To ensure smooth packet flow in a mixed routing environment of IPv4 and IPv6 networks.

  • So that IPv6 packets aren’t dropped in a pure IPv4 routing environment.

  • When you are transitioning your routing environment from IPv4 to IPv6 networks.

To enable the processing of IPv4-mapped IPv6 packets, use the allow-v4mapped-packets statement:


We recommend that you configure this statement only after fully understanding the security implications of allowing IPv4-mapped IPv6 packets in your network.

Process 6PE Traceroutes

In a dual-stack IPv6 network connected over an IPv4 MPLS network, the P routers in the IPv4 MPLS backbone do not have an IPv6 family. Consequently, the transit P routers are not shown in the output when you do an IPv6 traceroute. To generate an ICMPv6 echo request and a TTL expired response packet to and from the intermediate transit routers in the 6PE network, use the allow-6pe-traceroute statement: