Abstract

Given the business imperative to support remote workers, network managers are determined to learn how they can best utilize PC dial-up lines today. With that premise in mind, Ascend Communications commissioned The Tolly Group to evaluate its MAX 6000 remote access concentrator against Cisco Systems, Inc.’s Access Server 5300 (AS5300) and Lucent Technologies Inc.’s PortMaster 3. 

The Tolly Group conducted benchmarks which measured effective application performance using Ganymede Software’s Chariot test tool to transmit large files across all three products at 56 Kbit/s. Both analog and digital 56 Kbit/s modems were used, provided the vendors supported them. Testing was performed in February 1998. 

Ascend’s MAX 6000 delivered high throughput for both analog and digital connections and scaled as additional clients were added. Competing products tested exhibit either lower performance than the MAX 6000, rapid performance degradation as clients are added, or both. Chariot supported up to 92 simultaneous data transfers from servers on a central LAN to remote dial-up Windows 95 clients running MS- STAC compression. 

When using remote access concentrators, the effective application throughput is maximized by utilizing a compression algorithm prior to introducing any data to the wide area network. This compression can be done between the workstation and the remote ac- cess concentrator or between the modems. With Windows 95, Microsoft provides a compression routine that uses the Windows operating system and CPU to compress data prior to transport over the WAN. 

In cases of ASCII files, this can dramatically increase effective throughput. In a worst case scenario, when data is already in a compressed form, the Windows compression routine provides no additional benefit. (MS-STAC compression remained enabled in all the tests, even those where previously-compressed data was transferred.) In the tests, both conditions were examined, with up to 92 simultaneous client downloads to stress the products under test by creating a situation in which rapid client performance degradation could occur.