User Manual

C HAPTER 48 | IP Interface Commands
IPv6 to IPv4 Tunnels
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packets (by ensuring an IPv4 MTU of at least 1300 bytes is used) or by
preventing frequent changes to IPv4 routing.
◆ Packets delivered to transport protocols on the decapsulating node
should not be subject to ingress filtering. For bidirectionally configured
tunnels this is done by verifying that the source address is the IPv4
address of the other end of the tunnel. For unidirectionally configured
tunnels, the decapsulating node must be configured with a list of source
IPv4 address prefixes that are acceptable. Such a list must default to
not having any entries, i.e. the node has to be explicitly configured to
forward decapsulated packets received over unidirectionally configured
tunnels.
EXAMPLE
Console(config)#interface tunnel 2
Console(config-if)#tunnel destination 192.168.1.5
Console(config-if)#
tunnel mode ipv6ip This command sets the tunnel mode to manual configuration or 6-to-4
automatic tunneling. Use the no form to restore the default setting.
SYNTAX
tunnel mode ipv6ip {configured | 6to4}
no tunnel mode ipv6ip
configured - Configured IPv6 over IPv4 tunneling using point-to-
point tunnels by encapsulating IPv6 packets within IPv4 headers to
carry them over IPv4 routing infrastructures (based on RFC 2893).
6to4 - Transports IPv6 over IPv4 clouds by assigning a unique IPv6
address prefix to any site that currently has at least one globally
unique IPv4 address, and specifying an encapsulation mechanism
for transmitting IPv6 packets using such a prefix over the global
IPv4 network. (This method is based on RFC 3056.)
DEFAULT SETTING
configured
COMMAND MODE
Interface Configuration (IPv6/v4 Tunnel)
COMMAND USAGE
◆ Configured tunneling of IPv6 over IPv4 based on RFC 2893 uses point-
to-point tunnels made by encapsulating IPv6 packets within IPv4
headers to carry them over IPv4 routing infrastructures. These tunnels
can be either unidirectional or bidirectional. Bidirectionally configured
tunnels behave as virtual point-to-point links. When using configured
tunnels, the IPv4 tunnel end-point address must be manually
configured on the encapsulating node with the tunnel destination
command.