IP Configuration
IPv6 Management and Interfaces
Cisco 350, 350X and 550X Series Managed Switches, Firmware Release 2.4, ver 0.4 313
16
• 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 IPv6 Tunnel). 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.
A route defines the path between two network devices. Routing entries added by the user are
static, and are used by the system until explicitly removed by the user. They are not changed
by routing protocols. When static routes must be updated, this must be done explicitly by the
user. It is the user's responsibility to prevent routing loops in the network.
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