Brocade Multi-Service IronWare Switching Configuration Guide (Supporting R05.6.00) - Manual (Page 856)

826 Multi-Service IronWare Switching Configuration Guide
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IPv6 Over IPv4 tunnels in hardware
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Configuring an automatic 6to4 tunnel
An automatic 6to4 tunnel establishes a transient link between IPv6 domains, which are connected
by an IPv4 backbone. When needed, a device on which an automatic 6to4 tunnel is configured in
one domain can establish a tunnel with another similarly configured device in another domain.
When no longer needed, the devices take down the tunnel.
Instead of a manually configured tunnel destination, an automatic 6to4 tunnel constructs a
globally unique 6to4 prefix, which determines the tunnel destination. The 6to4 prefix has the
following format:
2002:::/48
When two domains need to communicate, a device creates a tunnel using the 6to4 prefix. The
software automatically generates the 6to4 prefix by concatenating a configured static IPv6 prefix of
2002 with the destination device’s globally unique IPv4 address. (Each device in an IPv6 domain
that needs to communicate over an automatic 6to4 tunnel must have one globally unique IPv4
address, from which the globally unique 6to4 prefix is constructed.) After the communication ends,
the tunnel is taken down.
FIGURE 205
Configuration notes on 6to4tunnels:
• This tunnel treats the IPv4 infrastructure as a virtual non-broadcast link and support multipoint
connectivity.
• Tunnel mode must be configured as ipv6ip 6to4.
• Tunnel source must be configured.
• Tunnel destination is not configured on 6to4 tunnel explicitly, as the destination is specified as
part of static nexthop or BGP nexthop.
• Static route with 2002::/16 MUST be configured.
• IPv6 address with 2002:A.B.C.D::/48 must be configured for the tunnel to come up (A.B.C.D is
the tunnel source IP address).
• You can have 6to4 tunnel with multiple nexthops depending on the IPv6 nexthop used to
forward the packets.
• With 6to4 tunnels, you can only use routing protocols (that is BGP+) that specify the nexthop in
the configuration.
• OSPFv3, IPv6 IS-IS and RIPng are not supported on the 6to4 tunnels.