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IPv6 Support on Devices Running Junos OS

IPv6 builds upon the functionality of IPv4, providing improvements to addressing, configuration and maintenance, and security. The following IPv6 features are supported:

  • IPv6 path maximum transmission unit (MTU) discovery

    Path MTU Discovery is used by single-source devices to determine the correct size of fragments. Path MTU Discovery is enabled for IPv6 packets by default.

  • Dynamic routes distribution through IS-IS and OSPF for IPv6

    Routers learn routes through different routing protocols such as OSPF, BGP, or IS-IS. Learned routes are put in the routing table to enable IPv6 traffic forwarding.

  • Dual stacking (IPv4 and IPv6)

    Dual stacking allows a device to run both IPv4 and IPv6 at the same time. End nodes, routers, and switches run both protocols and use IPv6 as the preferred protocol.

  • IPv6 forwarding

    The port forwarding engine software supports unicast IPv6 routes and next hops. This includes basic route infrastructure, next-hop support, network infrastructure, and exception packet processing.

  • IPv6 over MPLS (6PE)

    Devices can interconnect IPv6 islands over an MPLS-enabled IPv4 network. IPv6 information is sent over the MPLS core using MG-BGP with IPv4. The BGP Next Hop field conveys the IPv4 address of the router so that MPLS LSPs can be used without explicit tunnel configuration.

  • Neighbor Discovery

    The Neighbor Discovery protocol facilitates a substantial number of functions related to local network connectivity, datagram routing, and configuration. Both regular hosts and routers in an IPv6 environment count on the Neighbor Discovery protocol to facilitate the important exchanges of information that are necessary for proper internetwork operations. Neighbor Discovery is a messaging protocol similar to ICMP. The following functions are performed by the protocol:

    • Router discovery—How a host locates routers residing on an attached link.

    • Prefix discovery—How a host discovers address prefixes for destinations residing on an attached link. Nodes use prefixes to distinguish between destinations that reside on an attached link and those destinations that it can reach only through a router.

    • Parameter discovery—How a node learns various parameters (link parameters or Internet parameters) that it places in outgoing packets.

    • Address resolution—How a node uses only a destination IPv6 address to determine a link-layer address for destinations on an attached link.

    • Next-hop determination—The algorithm that a node uses for mapping an IPv6 destination address into a neighbor IPv6 address (either the next router hop or the destination itself) to which it plans to send traffic for the destination.

    • Neighbor unreachability detection—How a node determines that it can no longer reach a neighbor.

    • Duplicate address detection—How a node determines whether an address is already in use by another node.

  • Internet Control Message Protocol v6 (ICMPv6)

    ICMP sends error messages and information messages related to IP operations. ICMPv6 defines additional error messages and informational messages specific to IPv6.

    There are four different ICMPv6 error messages:

    • Destination Unreachable—A packet cannot be delivered due to an inherent problem with how it is being sent. Includes a code that indicates the nature of the problem that caused the packet not to be delivered

    • Packet Too Big—Sent when a packet is too large to be delivered.

    • Time Exceeded—A packet cannot be delivered because it has exceeded the hop count specified in the basic header hop-by-hop field.

    • Parameter Problem—Indicates a problem with a field in the IPv6 header or extension headers that makes it impossible to process the packet.

    ICMPv6 information messages are used for sharing the information required to implement various test, diagnostic, and support functions that are critical to the operation of IPv6. There are a total of eight different ICMPv6 informational messages:

    • Echo Request—

    • Echo Reply—

    • Router Advertisement—

    • Router Solicitation—

    • Neighbor Advertisement—

    • Neighbor Solicitation—

    • Redirect—

    • Router Renumbering—

  • Static routes for IPv6

    Routing information can be configured statically. Whenever a route is configured statically, the routing information base (RIB) is updated with routes specified through the static route. These routes should be configured statically in the “routing-options” hierarchy. The following configuration is used for enabling static routes for IPv6: