Wireless Roaming and Bridges
WLAN Roaming
Because wireless APs are relatively inexpensive, and the desire for bandwidth is high, most companies opt for deploying multiple APs with a reduced transmission radius and increased throughput. This solution introduces the need for a WLAN roaming scheme. Roaming describes switching from the control of one AP to another. You should position APs so there are no “dead spots.” As a user moves away from one AP, the power and signal quality decrease. A good roaming plan ensures that as this happens, another AP signal is sufficiently strong enough to take control of the wireless connection. The network controls this “handoff” transparently to the user.
Wireless handoff can only occur on the same WLAN. If a user moves between two WLANs, connectivity is lost until the device authenticates on the new WLAN.
Building-to-Building Bridge Systems
Wireless bridges create a single LAN by linking remote networks together. For simple networks, the bridge connects to a hub or a switch on the LAN. If the network contains multiple subnetworks, the bridge is connected to a router. Wireless bridges are a convenient and cost-effective solution for rapidly growing companies or for users located in areas where a fixed connection is either expensive or impractical.
In some cases, building-to-building wireless bridges offer superior price and performance over the following competing technologies:
- Direct cable connections:
- High installation costs
- Difficulty overcoming physical barriers such as lakes, highways, and other buildings
- Often require approval from local governments
- Inflexible after deployment
- Telephone-line connections
- High monthly service fees
- High installation and equipment costs
- Microwave connections
- Expensive
- Require licensing
- Difficult to install
Security Issues and Options
Security is a major concern for WLANs. The two main security issues for WLANs are:
- Access control—Because WLANs use radio waves for access, any WLAN client in the area is capable of accessing the network. Some hackers access networks while sitting in a car outside of a building. Businesses should protect their networks with centralized user-authentication schemes to protect against unauthorized access.
- Privacy—Privacy is also an issue with WLANs. Unlike fixed connections, which send information point to point, WLANs broadcast information everywhere. Hackers can “scoop” this information out of the air. Therefore, it is essential to encrypt the data packets that transmit through the air.
