1060 Configuring IPv6 RoutingHow Does IPv6 Compare with IPv4?There are many conceptual similarities between IPv4 and IPv6 networkoperation. Addresses still have a network prefix portion (network) and adevice interface specific portion (host). While the length of the networkportion is still variable, most users have standardized on using a networkprefix length of 64 bits. This leaves 64 bits for the interface specific portion,called an Interface ID in IPv6. Depending upon the underlying linkaddressing, the Interface ID can be automatically computed from the link(e.g., MAC address). Such an automatically computed Interface ID is calledan EUI-64 identifier, which is the interface MAC address with ff:fe inserted inthe middle.IPv6 packets on the network are of an entirely different format thantraditional IPv4 packets and are also encapsulated in a different EtherType(86DD rather than 0800 which is used with IPv4). The details forencapsulating IPv6 in Ethernet frames are described in RFC2462.Unlike IPv4, IPv6 does not have broadcasts. There are two types of IPv6addresses — unicast and multicast. Unicast addresses allow direct one-to-onecommunication between two hosts, whereas multicast addresses allow one-to-many communication. Multicast addresses are used as destinations only.Unicast addresses will have 00 through fe in the most significant octets andmulticast addresses will have ff in the most significant octets.How Are IPv6 Interfaces Configured?In PowerConnect 8000-series and 8100-series switches software, IPv6 coexistswith IPv4. As with IPv4, IPv6 routing can be enabled on VLAN interfaces.Each L3 routing interface can be used for IPv4, IPv6, or both simultaneously.Neighbor Discovery (ND) protocol is the IPv6 replacement for AddressResolution Protocol (ARP) in IPv4. The IPv6 Neighbor Discovery protocol isdescribed in detail in RFC4861. Router advertisement is part of the NeighborDiscovery process and is required for IPv6. As part of router advertisement,PowerConnect 8000-series and 8100-series switches software supportsstateless auto configuration of end nodes. The switch supports both EUI-64interface identifiers and manually configured interface IDs.While optional in IPv4, router advertisement is mandatory in IPv6. Routeradvertisements specify the network prefix(es) on a link which can be used byreceiving hosts, in conjunction with an EUI-64 identifier, to autoconfigure a
