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Configuring IPv6 IPv6 Overview
OmniSwitch 6600 Family Network Configuration Guide April 2006 page 15-7
Stateless autoconfiguration is not available for assigning a global unicast or anycast address to an IPv6
interface. In other words, manual configuration is required to assign a non-link-local address to an inter-
face. See “Assigning IPv6 Addresses” on page 15-12 for more information.
Both stateless and stateful autoconfiguration is supported for devices, such as a workstation, when they are
connected to the switch. When the stateless method is used in this instance, the device listens for router
advertisements to obtain a subnet prefix. The unicast address for the device is then formed by combining
the subnet prefix with the interface ID for that device.
Stateful autoconfiguration refers to the use of an independent server, such as a DHCP server, to obtain an
IPv6 unicast address and other related information. Of course, manual configuration of an IPv6 address is
always available for devices as well.
Regardless of how an IPv6 address is obtained, duplicate address detection (DAD) is performed before the
address is assigned to an interface or device. If a duplicate is found, the address is not assigned. Note that
DAD is not performed for anycast addresses.
Please refer to RFCs 2462, 2464, and 3513 for more technical information about autoconfiguration and
IPv6 address notation.
Tunneling IPv6 over IPv4
It is likely that IPv6 and IPv4 network infrastructures will coexist for some time, if not indefinitely.
Tunneling provides a mechanism for transitioning an IPv4 network to IPv6 and/or maintaining interopera-
bility between IPv4 and IPv6 networks. This implementation of IPv6 supports tunneling of IPv6 traffic
over IPv4. There are two types of tunnels supported: 6to4 and configured.
Note. RIPng is not supported over 6to4 tunnels. However, it is possible to create a RIPng interface for a
configured tunnel. See “Configuring IPv6 Tunnel Interfaces” on page 15-14 for more information.
6to4 Tunnels
6to4 tunneling provides a mechanism for transporting IPv6 host traffic over an IPv4 network infrastruc-
ture to other IPv6 hosts and/or domains without having to configure explicit tunnel endpoints. Instead, an
IPv6 6to4 tunnel interface is created at points in the network where IPv6 packets are encapsulated (IPv4
header added) prior to transmission over the IPv4 network or decapsulated (IPv4 header stripped) for
transmission to an IPv6 destination.
An IPv6 6to4 tunnel interface is identified by its assigned address, which is derived by combining a 6to4
well-known prefix (2002) with a globally unique IPv4 address and embedded as the first 48 bits of an IPv6
address. For example, 2002:d467:8a89::137/64, where D467:8A89 is the hex equivalent of the IPv4
address 212.103.138.137.
6to4 tunnel interfaces are configured on routers and identify a 6to4 site. Because 6to4 tunnels are point-to-
multi-point in nature, any one 6to4 router can communicate with one or more other 6to4 routers across the
IPv4 cloud. Two common scenarios for using 6to4 tunnels are described below.