![]() ![]() ATM Backbone Switches The ASX-1000 is designed to scale to even the largest ATM backbone needs. With support for up to 64 OC-3 or 16 OC-12 modules, the ASX-1000 was the highest density switch we tested. The switch consists of four 2.5-Gbps ATM fabrics linked by another internal 10-Gbps switching fabric. Each of the four 2.5-Gbps fabrics may have a backup switch control processor, resulting in an ultra-high availability switch. Once populated with a switch control processor, each fabric can hold four ATM network modules. You can choose from a variety of OC-3, OC-12, ATM25 and T1/E1 interfaces. We tested a four-port OC-3 module and a one-port OC-12 module. The cell-buffering capacity of the ASX-1000 is outstanding. The capacity of the switch grows with each adapter module you add. The switch itself has 16,000 internal cell buffers. Each OC-3 module adds 32,000 more buffers, while each OC-12 module adds 64,000 cell buffers. The ASX-1000 is a completely output-buffered switch, ensuring that no head-of-line blocking can occur. The ASX-1000 is loaded with redundancy features to keep your enterprise running smoothly. In addition to its hot-swappable switch control processors, the ASX-1000 features dual hot-swappable, load-sharing power supplies. On the software side, FORE's ForeThought supports redundant LES/BUS (LAN Emulation Server/Broadcast and Unknown Server) pairs distributed across multiple switches to provide LANE (LAN Emulation) protection. The ASX-1000 doesn't include LECS (LAN Emulation Configuration Server) redundancy, a feature we feel is important for a truly fault-tolerant setup. The beefy fabric of the ASX-1000 can support up to 100,000 concurrent VCCs (virtual channel connections), as well as 16,000 root multicast VCCs. Another unique feature of the ASX-1000 is its per-VC (virtual circuit) queuing mechanism--12,000 VCs per class o f service allow the ASX-1000 to queue LAN traffic extremely efficiently, which was reflected in the EPD/PPD (Early Packet Discard/Partial Packet Discard) tests we conducted. The hardware is also fully primed to support hardware-based Explicit Rate ABR (Available Bit Rate) flow control when the firmware update is released next spring. The hardware features of the ASX-1000 are backed by a great set of software options. In addition to per-VC queuing, the ForeThought software offers Phase 1 PNNI support for plug-and-play ATM connections, as well as support for an MPOA (Multiprotocol Over ATM) client. This same software will power FORE's entire line of products, which will support MPOA by press time. If we had a complaint about the ASX-1000, it would have to do with the sluggish response of its management software--but FORE's product was not alone in falling short in this regard (see "How Will You Ever Manage?" page 90). The distributed nature of ATM's features and services make it inherently difficult to manage. For example, to set up an ELAN (emulated LAN) with Ethernet clients on the edge device, you must first configure the LECS on your network to know about the ELAN. Then you must configure an LES/BUS pair with the ELAN's name. If you want fault tolerance, you'll need to configure two of these--but only if the vendor supports redundant LES/BUS pairs. Once you've got the ATM services running, you'll have to tell the edge switch which ports belong on that ELAN. If everything is set up right, you'll have a new emulated LAN on your network.
Overall, its management inefficiencies notwithstanding, the ForeRunner ASX-1000 offers top-of-the-line performance and excellent value. How We Tested
Can NT Balance the Network Management Load?
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In a GUI environment, you have to rely on the vendor's user interface to do all of this for you. Once you've got everything up and running, it would be worthwhile to monitor the ELAN for performance characteristics, security intrusions, or any other alarms you might want to set. The GUI should also let you manage services and connections on a per-switch, per-port basis. All of this is easier said than done, unfortuna
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