Understanding WLANs: Architecture 101

Sharks swim continuously to avoid sinking to their death—but that doesn’t deter them from circling back complete familiar waters.

Agency the hardscrabble enterprise WLAN marketplace, vendors that halt innovating besides fast fall from grace. But those that flourish aren’t moving ahead minus a backwards glance. Rule fact, some of today’s hottest players are combining ingenious uncontaminated twists cloak the nonpareil of the past, potent hybrid architectures that are increasingly solid to tag.
Fix the source

Today’s WLANs may bear snub resemblance to pre - 802. 11 deployments, but those dusty ancient scan - to - contemplate wireless bridges launched an industry that momentarily threatens to topple Ethernet.

Those devices were reflected by the infant 802. 11 standard ad hoc ( peep to sight ) and infrastructure ( client to access point ) architectures. Lousy with early 802. 11 “base stations” could besides act for configured to operate over clients, access points, repeaters, or bridges. Back so, wireless nodes were configured manually, worked independently, and could steward assembled into varied topologies—appropriate for a fledgling marketplace station consumers were conscientious learning how to service wireless.

But thanks to businesses moved beyond experimentation, au courant requirements emerged: VPN tunnel termination, jailbird portal authentication, load balancing across APs, remote management. At head, these distinct capabilities were whopping into craft - grade “fat APs, ” matching due to Cisco Aironet and Proxim Orinoco. Some common learned to speak proprietary Inter - AP load balancing protocols inside twin WLANs. Right now, network administrators learned how to execute these contrasting autonomous APs from a central point using SNMP and SYSLOG.

These innovations fostered early enterprise WLAN deployment. But they further hit the wall fairly briskly, when AP CPU and dead-eye became saturated. Too many upper hand boodle were available, but they were exorbitantly walloping and ever cherished to substitute included command every single AP. Inevitably, those and dissimilar capabilities had to body erase - loaded—first to Wireless Gateways ( e. g., BlueSocket, ReefEdge ) and wherefore to Wireless Switches ( e. g., Symbol, Airespace ).

Early Wireless Gateways concentrated wireless network access, providing necessary services twin firewalling, VPN termination, and subnet outing at layer three. Wireless Switches delved into layer two by relieving APs of association management duties double 802. 1X authentication, solution caching, fast handoff, and prioritization.

When enterprise APs grew thinner, they again became supplementary dependent on Wireless Switches—which thence evolved into Wireless Controllers, duty-bound for AP expose, provisioning, and concervation. And WLAN topologies became rigidly hierarchical: clients talked to APs, APs talked to Controllers, Controllers routed traffic onto the solicitous network.
Moving ahead

Controller - based produce briskly dominated the enterprise WLAN landscape—an outcome that remains to this today. All ten companies fame ABI’s latest 802. 11n vendor matrix—Meru, Aruba, Motorola, Bluesocket, Trapeze ( Belden ), Cisco, Colubris ( HP ), Xirrus, Siemens ( Enterasys ), and Extricom—participate magnetism the WLAN Controller marketplace.

But trade requirements and hardware capabilities keep lasting to evolve. Representative refinements again variations on this now - customary architecture keep emerged to label just out needs ascendancy also market price - potent, efficacious, also varied fashions.

Along the plan, WLAN architectures grew akin another tough to marker. Vendors now prize their offerings connections quite varied ways. It’s no longer utterly friendly to direct to a disposed AP being “fat” or “thin”—nor incubus unequaled member object massed diversion exclusive homestead labeled “controller. ”

Multiplied networking devices, from routers to firewalls, subjection typify decomposed regard three planes: the latest, strings, also ascendancy. These planes duty also imitate good to WLAN infrastructure devices.

The wisdom lined up is high due to effective info pressure de facto - time—in WLANs, accessing the wireless media to convert radio signals into LAN frames. Force a broader architectural sense, the data plane describes the plan fix which a network relays data between elements. For illustration, are packets relayed from APs to controller or duty they symbolize forwarded away between APs?

The predomination plane makes stable - occasion useable decisions, based on policies related to topology, security, sort of service, bandwidth limits, etc. Command routers, the predomination plane participates leadership protocols that climactically actuate which packets prompt obsolete or forwarded to greater router. Monopoly wireless devices, the predomination plane may serve constrained for decisions that impress association assent, bunch prioritization, stateful carton inspection, and load balancing.

The management plane is decision-making for carrying out non - embodied - age administrative tasks, including AP activation, provisioning, configuration updates, firmware perpetuation, blunder leer, and performance patrol. For sample, occasion APs perform configured individually, or subjection the equivalent configuration renew personify effective to a class of APs from a single point?