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Understanding Wireless Bridging

 

Wireless bridging is a common technique to accommodate multiple buildings in one company or other entity. Legitimate wireless bridging between two buildings is accomplished with an extension of wireless mesh, a service that enables access points to connect to each other using their radios. You must use mesh to enable bridging. (For more information about wireless mesh, see Understanding Wireless Mesh .) The most typical application of wireless bridging is to provide network connectivity between two buildings using an outdoor wireless link, as shown in Figure 1.

Figure 1: Wireless Bridging Between Two Buildings
Wireless Bridging Between
Two Buildings

A wireless bridge uses two access points as the bridge endpoints in a transparent Layer 2 bridge. As long as there is a clear RF line of sight between the access points, and the distance between the access points is within the capability of the access points, the bridge can connect another building or remote area.

This topic describes:

Why Use Wireless Bridging?

Wireless bridging is frequently used with outdoor access points to connect two buildings. In Figure 1, the network is located in Building 1. Instead of running cable between the two buildings, which is more expensive, two outdoor access points have been configured for wireless mesh. The access point outside of Building 2 is connected to the network in Building 1—that is why the access point on both buildings is a dual-radio network portal. For a description of mesh portals and mesh access points, see Understanding Wireless Mesh .

How Does Wireless Bridging Work?

Wireless bridging is a special case wireless mesh network. A wireless bridge is established between a wired mesh portal access point and an associated mesh access point as shown in Figure 1. A wireless bridge can also consist of two mesh portals. In this case, both outdoor access points must be dual-radio access points, with one of their radios configured with a mesh WLAN Service profile.

When a bridge is operating, a mesh access point serving as a bridge endpoint picks up packets from the wired port and transfers them to the other bridge endpoint. A simple source-destination learning mechanism is used to avoid forwarding unnecessary packets across the bridge.

How is Wireless Bridging Configured?

You need to do the following to create a wireless bridge:

  • Configure a mesh SSID (WLAN Service profile)—be sure to enable Bridging when you enable Mesh on the Basic Settings tab.

  • Connect access points to a controller and configure them to work as the points of a wireless bridge.

  • Disconnect the access points from the controller and place them in the bridge configuration.