Abstract

In the past, Small Office/Home Office (SOHO) sites rarely had connections to corporate LANs. This was because neither of the available connectivity options could deliver both acceptable performance and reasonable cost. Leased lines offered good performance but often at too high a price. Inexpensive dial-up analog links proved too slow for handling bandwidth-hungry LAN applications. Today, the Integrated Services Digital Network (ISDN) presents a viable option. ISDN is an increasingly popular wide area network service capable of combining high bandwidth (128 Kbit/s or greater) with a cost-effective, usage-based “dial up” implementation. The worldwide availability of ISDN brings high-powered internetworking into the realm of possibility for the SOHO user.

In addition to being a viable option for a primary connection, ISDN can be employed as a secondary connection between distant LANs. When used as a secondary connection in conjunction with leased lines, ISDN provides supplemental “bandwidth on demand” or emergency backup in the event of a primary service failure. ISDN brings to the corporate LAN a completely new set of network design challenges that did not exist with traditional leased lines, such as the need for cost control, security and more complex network management.

Cisco Systems commissioned The Tolly Group to demonstrate the effectiveness of Cisco’s ISDN product set, including the 1000, 2500, 4000, and 7000 series routers (all run the Cisco Internetwork Operating System (Cisco IOSTM) version 11.0(2.3)) running actual AppleTalk, IP, and NetWare (IPX) environments. The Tolly Group examined several aspects of ISDN that are important to SOHO and headquarters use: basic dial-on-demand connectivity for primary ISDN connections and leased line backup, bandwidth aggregation, performance (dual B-channels with compression), cost control via link/ tariff management, security, and network management.

Test Results Test results indicate the Cisco products tested offer extensive provisions for effective ISDN use including a complete set of features for dial-on-demand, tariff/link management, performance, security, management and ISDN backup for leased lines. Additionally, Cisco has successfully inte- grated a number of ISDN features, such as PPP Multilink and Tariff Management, into the Cisco IOS software for the 1000, 2500, 4000, and 7000 series routers. Cisco rounds out its ISDN product line with the Cisco 200 series (from the acquisition of Newport Systems, Inc.) and the 750 series (from the acquisition of Combinet Corp.). Cisco IOS software has been incorporated into the entire Cisco product line. Neither the PC-based 200 series nor the standalone 750 series were tested in this evaluation.