Frame Relay hits turbo speed

Recent reports from industry analysts have underscored the business world's move to higher speeds. According to Infonetics Research Inc., companies want-and are willing to pay for-high-speed Internet access. In its December 1996 network strategies report evaluating connections to Web servers, Forrester Research found that nearly two-thirds of network designers polled said they would require 45 Mb/s connections within two years.

A number of factors are driving these trends. Corporate customers are migrating to switched networks to give desktop users more bandwidth for LAN and SNA applications. Aggregation points within these switched networks-such as data centers, corporate headquarters and Web sites-are increasingly requiring higher-speed wide area network interconnections.

Other driving factors include increasing Internet usage and the growth of corporate intranets. These applications are creating demand for increased bandwidth as greater volumes of information-much of it graphical-become accessible to end users. To serve these users, ISPs are requiring high-speed uplinks to the Internet.

Together, these factors are causing tremendous proliferation of T-1 access lines. Large ISPs among Cascade's installed base now are provisioning T-1 lines at the rate of one every few minutes-up significantly from six months ago, when one line was provisioned every few hours, and one year ago, when one was provisioned every few days.

Upgrading existing frame relay networks to high-speed frame relay will allow service providers to meet customer demands and generate higher revenue while leveraging existing investment in infrastructure. High-speed frame relay is a standards-based technology that uses existing switches to upgrade frame relay to T-3 speeds. It can provide channelized and unchannelized connections, delivering either higher-density T-1 or higher-speed T-3, and it can generate additional revenues with a minimal infrastructure upgrade.

Channelized high-speed frame relay technology lowers per-port costs by increasing port densities per switch. Lower per-port costs can enable providers to offer services at a lower cost to their customers, and higher densities enable them to make those services available on a wider scale.

Access or trunking High-speed frame relay upgrades existing frame relay by improving access and trunking.

On the access side, high-speed frame relay can increase bandwidth to a full 45 Mb/s, enabling providers to provision high-speed lines supporting the T-3 User-Network Interface (UNI). This increased capacity addresses the growth in corporate intranets and the need for access at speeds greater than T-1 to accommodate Web server and Internet connections.

For access applications, a 45 Mb/s high-speed frame relay line is implemented by installing a high-speed serial interface module in a slot on the carrier's frame relay switch (Figure 1).

For trunking applications, high-speed frame relay consolidates multiple access lines into a single high-speed T-3 trunk and uses software rather than physically provisioning lines. In this configuration, 28 T-1 lines can be connected through a digital cross-connect system to a single T-3 line, which connects to a T-3 module that uses one slot on the carrier's switch (Figure 2). This configuration previously required three slots to support the same number of T-1 lines, and each line would have required an individual connection into and out of the DCS (Figure 3).

For subscribers, the best time to upgrade to high-speed frame relay access is when network response time slows to the point where it affects user productivity. If retrieving information from the corporate intranet takes so long that employees cannot effectively use the resource, high-speed frame relay makes sense. For ISPs and carriers, when trunks exhibit an unacceptable level of dropped packets and design issues are ruled out, high-speed frame relay becomes a valid option.

Many niches Overall, high-speed frame relay allows carriers and ISPs to bolster service speed and scalability while retaining the cost-effectiveness of traditional frame relay. High-speed frame relay retains this cost efficiency by concentrating multiple circuits, saving space, simplifying and reducing physical cabling and improving network management. Also, because high-speed frame relay requires fewer lines and ports, management and network troubleshooting is easier.

High-speed frame relay will be critical for applications that consume bandwidth, such as medical imaging, as well as for handling the increased volume of graphical content from the Internet and corporate intranets. On busy Web sites, for example, bottlenecks can be eliminated by provisioning high-speed UNI access pipes between the server and the frame relay network. High-speed frame relay will enable carriers and ISPs to provide fast access to even the highest-volume Web sites.

Proliferation of high-speed frame relay will drive the need for solutions that integrate with core OC-3 and OC-12 asynchronous transfer mode backbones.

Frame-to-ATM interworking can be used to integrate high-speed frame relay into ATM backbones, creating infrastructure solutions that accommodate growing bandwidth demands.

High-speed frame relay is also important for networks with multiple remote sites connecting to a single data center such as an SNA network. A high-speed link can provide these networks with access to a data center or corporate headquarters without the use of multiple physical ports.

Rapidly changing technologies, increasingly complex applications and network growth will continue to drive changes in the data services market. By providing complete and flexible solutions that effectively scale large installed networks, high-speed frame relay goes a long way in helping carriers and Internet service providers meet these challenges.

Heidi Hudson Brandte is Senior Product Marketing Manager for Cascade Communications Corp., Westford, Mass.