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Also, vendors tend to differentiate their products by adding proprietary features, which can complement exis ting standards or anticipate future standards-based functionality. It is prudent, therefore, to limit your suppliers to as few as possible. You should evaluate a vendor's strengths and weaknesses--for these enhanced features and in other areas of your enterprise network, such as routing, legacy switching, desktop connectivity and remote access--when building your short list.

Also remember that ATM switches are blissfully unaware of LANE, but they play an integral role in LANE performance (see "I'd Rather Switch Than Fight," on page 126). Remember, too, that your vendor's strategic direction should be closely aligned with yours.

For instance, if you're planning on implementing LANE in your network on an enterprise scale, you'll probably also transition to Multi-Protocol Over ATM (MPOA) to take advantage of cut-through routing and quality of service (QoS) features. If standards-based redundancy is important to your enterprise, you'll want your vendor to implement LA NE version 2.0, which lets you provisio n backup LANE servers. If you need redundancy now, solutions that implement LANE services redundancy and require only that a LAN Emulation Client (LEC) implement some optional pieces of LANE 1.0 are available--Cisco Systems' Simple Server Redundancy Protocol (SSRP) is one example of such a product. Finally, the ATM Forum's User-to-Network Interface (UNI) 4.0 and Available Bit Rate (ABR) specifications optimize resource utilization by adding support for QoS signaling and flow control.

Under Control The ATM Forum wisely separated LANE control message processing (LECS and LES) from data forwarding (LEC and BUS). Some vendors have taken advantage of this to optimize hardware for one or the other environment. In the former case, you'll typically see a hefty general-purpose CPU under the hood; in the latter, you'll likely encounter hardware ASICs.

In cases where a vendor has bolted LANE onto an existing product to get to market quickly, you should scrutinize the optimality of the platform.

If the LECS or LES is implemented in a nondedicated device, such as a router, make sure that other processes in the router don't impede the performance of the LANE service (and vice versa). If the LECS or LES is located in a dedicated server or workstation, keep in mind the robustness, manageability and performance characteristics of the resident operating systems and the network platform's I/O performance.

A LEC must be able to find the LECS no matter where the LECS is located. LANE 1.0 specifies three mandatory mechanisms that must be tried in sequence. However, an addendum to LANE lets a client use a locally configured address. At least one major vendor uses this addendum to forestall implementation of the first of these mechanisms: discovering the LECS address via the Interim Local Management Interface (ILMI). This is a shame since ILMI LECS discovery provides the greatest degree of scalability. If you plan to implement several LECS (to scale your network or provide several administrative domains), insist t hat your vendor provide ILMI LECS discovery in its LEC and supports this feature in its ATM switches.

To download an Adobe Acrobat .pdf format version of the LANE-Enabled ATM Products Buyer's Guide charts, click here.