How Does IPv6 Compare with IPv4?
There are many conceptual similarities between IPv4 and IPv6 network
operation. Addresses still have a network prefix portion (subnet) and a device
interface specific portion (host). While the length of the network portion is
still variable, most users have standardized on using a network prefix length of
64 bits. This leaves 64 bits for the interface specific portion, called an
Interface ID in IPv6. Depending upon the underlying link addressing, the
Interface ID can be automatically computed from the link (e.g., MAC
address). Such an automatically computed Interface ID is called an EUI64
IPv6 packets on the network are of an entirely different format than
traditional IPv4 packets and are also encapsulated in a different EtherType
(contained within the L2 header to indicate which L3 protocol is used). In
order to route these packets across L3 requires an infrastructure equivalent to
and parallel to that provided for IPv4.
How Are IPv6 Interfaces Configured?
In PowerConnect M6220/M6348/M8024/M8024-k switch software, IPv6
coexists with IPv4. As with IPv4, IPv6 routing can be enabled on VLAN
interfaces. Each L3 routing interface can be used for IPv4, IPv6, or both.
Neighbor discovery is the IPv6 replacement for Address Resolution Protocol
(ARP). Router advertisement is part of the neighbor discovery process and is
required for IPv6. As part of router advertisement, PowerConnect
M6220/M6348/M8024/M8024-k switch software supports stateless auto
configuration of end nodes. The switch supports both EUI-64 interface
identifiers and manually configured interface IDs.
While optional in IPv4, router advertisement is mandatory in IPv6. Router
advertisements specify the network prefix(es) on a link which can be used by
receiving hosts, in conjunction with an EUI-64 identifier, to autoconfigure a
host's address. Routers have their network prefixes configured and may use
EUI-64 or manually configured interface IDs. In addition to zero or more
global addresses, each IPv6 interface also has an autoconfigured link-local
address which is:
Allocated from part of the IPv6 unicast address space
Not visible off the local link
Not globally unique
Configuring IPv6 Routing