Address Structure; Ipv6 Support On Acx Series Universal Access Routers - Juniper ACX1000 Configuration Manual

IPv6 Support on ACX Series Universal Access Routers

Copyright © 2017, Juniper Networks, Inc.
Multicast addresses support 16 different types of scope, including node, link, site,
organization, and global scope. A 4-bit field in the prefix identifies the scope.

Address Structure

Unicast addresses identify a single interface. The address consists of n bits for the prefix,
and 128 – n bits for the interface ID.
Multicast addresses identify a set of interfaces. The address is made up of the first 8 bits
of all ones, a 4-bit flags field, a 4-bit scope field, and a 112-bit group ID:
11111111 | flags | scope | group ID
The first octet of ones identifies the address as a multicast address. The flags field
identifies whether the multicast address is a well-known address or a transient multicast
address. The scope field identifies the scope of the multicast address. The 112-bit group
ID identifies the multicast group.
Similar to multicast addresses, anycast addresses identify a set of interfaces. However,
packets are sent to only one of the interfaces, not to all interfaces. Anycast addresses
are allocated from the normal unicast address space and cannot be distinguished from
a unicast address in format.
IPv6 builds upon the functionality of IPv4, providing improvements to addressing,
configuration and maintenance, and security. The following IPv6 features are supported
on ACX Series routers:
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 ACX Series 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)
ACX Series Universal Access Routers 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.
Chapter 18: Configuring Routing Protocols
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