Cisco 350XG series Administration Manual page 350

IP Configuration
IPv6 Management and Interfaces
Cisco 350XG & 550XG Series 10G Stackable Managed Switches
• IPv6 Prefix List
• IPv6 Access Lists
• IPv6 Routes
• DHCPv6 Relay
Overview
The Internet Protocol version 6 (IPv6) is a network-layer protocol for packet-
switched internetworks. IPv6 was designed to replace IPv4, the predominantly
deployed Internet protocol.
IPv6 introduces greater flexibility in assigning IP addresses, because the address
size increases from 32-bit to 128-bit addresses. IPv6 addresses are written as
eight groups of four hexadecimal digits, for example
FE80:0000:0000:0000:0000:9C00:876A:130B. The abbreviated form, in which a
group of zeroes can be left out, and replaced with '::', is also acceptable, for
example, ::-FE80::9C00:876A:130B.
IPv6 nodes require an intermediary mapping mechanism to communicate with
other IPv6 nodes over an IPv4-only network. This mechanism, called a tunnel,
enables IPv6-only hosts to reach IPv4 services, and enables isolated IPv6 hosts
and networks to reach an IPv6 node over the IPv4 infrastructure.
Tunneling uses either an ISATAP or manual mechanism (see
Tunneling treats the IPv4 network as a virtual IPv6 local link, with mappings from
each IPv4 address to a link local IPv6 address.
The device detects IPv6 frames by the IPv6 Ethertype.
In the same way as occurs in IPv4 routing, frames addressed to the devices's MAC
address, but to an IPv6 address that is not known to the device, are forwarded to a
next-hop device. This device may be the target end-station, or a router nearer the
destination. The forwarding mechanism entails re-building a L2 frame around the
(essentially) unchanged L3 packet received, with the next-hop device's MAC
address as the destination MAC address.
The system uses Static Routing and Neighbor Discovery messages (similar to IPv4
ARP messages) to build the appropriate forwarding tables and next-hop
addresses.
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IPv6 Tunnel).
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