The ExtremeXOS software supports Layer 3 tunnels, which serve as a transition option (6in4 and 6to4 tunnels only), as networks change over from IPv4 to IPv6. The software supports these tunnels in Default-VR.



IPv6 tunnels are supported only in Default-VR. IPv6 tunnels are not supported for ExtremeSwitching X435, X440-G2, and X620 switches.

The ExtremeXOS software supports the use of IPv6-in-IPv4 tunnels (known as configured tunnels or 6in4 tunnels) and IPv6-to-IPv4 tunnels (known as 6to4 tunnels). Both types of tunnels are used to connect regions of IPv6 routing across a region of IPv4 routing. From the perspective of the router, the tunnel across the IPv4 region is one hop, even if multiple IPv4 routers are traversed during transport.

A 6in4 tunnel connects one IPv6 region to one other IPv6 region.

Multiple 6in4 tunnels can be configured on a single router to connect with multiple IPv6 regions. Dynamic and static routing can be configured across a 6in4 tunnel. Hosts in the IPv6 regions need not know anything about the configured tunnel, since packets destined for remote regions are sent over the tunnel like any other type of routing interface.

A 6to4 tunnel connects one IPv6 region with multiple IPv6 regions. Only one 6to4 tunnel can be configured on a single router.

GRE (Generic Router Encapsulation) is a tunneling mechanism where the customer network IP packet is encapsulated by a IP+GRE header across a network infrastructure. The decapsulation is done at the remote gateway providing the original IP datagram delivered to the peers local network. The GRE tunnel is a point-to-point path between two sites, in most cases the tunnel is used to enable communication between sites using private address spaces across a service provider network or third-party network.