About ip tunnels – Allied Telesis AT-WL2411 User Manual
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AT-WL2411 Version 1.80 Installation and User’s Guide
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About IP Tunnels
The physical boundary of a wireless network is usually defined by the
presence of an IP router. Multiple independent wireless networks may
exist, each with its own LAN ID, root access point, and set of wireless end
devices. In this environment, an end device can only operate within the
limited coverage area of its own network and cannot roam across IP
subnet boundaries. However, using IP tunnel technology, end devices
now can roam across subnet boundaries. This technology is designed to
safely and transparently coexist with routed IP installations while
supporting mobility for end devices. IP tunnels do the following:
❑ Enables access points on different subnets to belong to the same
wireless network.
❑ Supports transparent roaming of end devices between access
points that are on different subnets without losing network
connections.
❑ Supports end devices using both IP and other routable or
nonroutable protocols.
The AT-WL2411 consists of a group of multiport Ethernet-to-wireless
bridges. The IP tunnel port uses a standard IP protocol called Generic
Routing Encapsulation (GRE) to encapsulate a frame. These
encapsulated frames can use normal IP routing to pass through IP
routers. Unlike the physical Ethernet and radio ports, the IP tunnel port
does not have its own output connector. It is a logical port that provides
IP encapsulation services for frames that must be routed to reach their
destinations. Once frames are encapsulated, they are transmitted or
received through a physical port.
In other words, IP tunnels use encapsulation to establish a virtual LAN
segment through IP routers. The virtual LAN segment includes the home
IP subnet and logically extends to include end devices attached to
access points on remote IP subnets. An IP tunnel becomes a branch in
the spanning tree. Access points on remote subnets can be directly
connected to an IP tunnel or indirectly connected through another
access point on a remote subnet.