Wireless LANs Describing WLAN Topologies WLAN Topologies Wireless

Wireless LANs Describing WLAN Topologies

WLAN Topologies • Wireless client access – Mobile user connectivity • Wireless bridging – LAN-to-LAN connectivity • Wireless mesh networking – Combination of bridging and user connectivity

WLAN and LAN

Service Set Identifier (SSID) • SSID is used to logically separate WLANs. • The SSID must match on client and access point. • Access point broadcasts one SSID in beacon. • Client can be configured without SSID. • Client association steps: 1. Client sends probe request. 2. A point sends probe response. 3. Client initiates association. 4. A point accepts association. 5. A point adds client MAC address to association table.

WLAN Access Topology

Wireless Repeater Topology

Workgroup Bridge Topology

Alternative Peer-to-Peer Topology

Service Sets and Modes Ad hoc mode • Independent Basic Service Set (IBSS) – Mobile clients connect directly without an intermediate access point. Infrastructure mode • Basic Service Set – Mobile clients use a single access point for connecting to each other or to wired network resources. • Extended Services Set – Two or more Basic Service Sets are connected by a common distribution system.

Roaming Through Wireless Cells Roaming

Client Roaming • Maximum data retry count exceeded • Too many beacons missed • Data rate shifted • Periodic intervals • Roaming without interruption requires the same SSID on all access points.

Layer 2 vs. Layer 3 Roaming

Wireless VLAN Support • Multiple SSIDs • Multiple security types • Support for multiple VLANs from switches • 802. 1 Q trunking protocol

Wireless VLAN Support (Cont. ) • VLANs propagate across access points. • VLAN numbers are unique. • Access points handle up to 16 VLANs.

Enterprise Voice Architecture

Wireless Mesh Networking In a mesh network topology, devices are connected with redundant connections between nodes.

Wireless Mesh Networking • Mesh access points automatically establish connection to controller. – Rooftop access points (RAP) connect via wired connection. – Mesh access points (MAP) connect via self-configuring backhaul connection. • Cisco uses mesh access points. • Adaptive Wireless Path (AWP) protocol establishes best path to root. • Access point authenticates to controller and downloads configuration and radio parameters.

Adaptive Wireless Path Protocol (AWP) AWP protocol establishes an optimal path to root. Each access point carries a feasible successor or successors if topology or link health changes. AWP uses a “parent sticky” value to mitigate route flaps.

Key Market Segments for Outdoor Wireless Enterprise outdoor • Indoor and outdoor wireless solutions for education customers. • Rugged mesh solutions for enterprise customers. Public sector • Connecting peripheral devices across the mesh. • Establishing hot zones for public safety or municipal departments. Service provider • Hot spots become hot zones with Wi-Fi access.

Summary • Types of WLAN topologies are client access, bridging, and mesh networking. • Wireless networks are built with multiple wireless cells. • WLAN roaming occurs seamlessly between wireless cells. • WLANs support VLANs and Qo. S. • WLAN mesh networks extend the wireless network beyond the boundaries of wired LANs.