Frame Relay Ma kes Its Voice Heard Heard It on the Frame Vine To produce a viable voice offering, carriers must eliminate significant delays from the source CPE through the backbone and out to the target CPE. Only the carriers that have spent the time and money replacing older switches and carefully planning their networks from the start will find this task possible. Upgrading older switches to higher-end equipment from vendors such as Cascade Communications Corp. and StrataCom is a very expensive undertaking, but doing so allows prioritization techniques, advanced bandwidth management and the congestion control needed to handle the load. This can all be accomplished while the carrier provides better data management service to the customer. Nonetheless, the carriers must work carefully with chosen CPE vendors to maximize the likelihood of fulfilling performance guarantees. Take for instance, a F RAD that prioritizes data to certain data link connection identifiers (DLCIs), giving voice priority over any data packets. The carrier can work with a prioritizing feature that delivers the data to the backbone, then continue its own frame prioritization to carry the frames through the backbone and count on the same CPE equipment to perform on the same level at the other side. On the other hand, FRADs with impressive compression, for example, can sometimes accentuate the carrier network's flaws by making delayed traffic or packets lost in route less tolerable as the amount of information crammed into a single packet grows. Guaranteeing Service Most carriers aren't prepared for voice over frame relay and will not guarantee any level of voice over frame relay for some time. Some carriers have no plans to offer this service-level guarantee ever. In fact, there are only two that offer it today: Intermedia Communications International (ICI) and Infonet Services Corp., and both have taken different approaches to solving the performance problems. One way to approach the problem of latency and reliability is to throw money at it, which, as it turns out, works quite well. ICI has done this from the start, building its network with high-end Cascade switches, which not only allow prioritization, control and management functionality, but also allow for redundancy and fallback into the network backbone to protect the critical voice operations between branch offices. This approach costs more money up front, but will let ICI offer CPE equipment that supports an upcoming voice-over-frame-relay standard under development by the Frame Relay Forum. Admittedly, the approach of overengineering with new equipment is not so easy for more established and much larger companies, such as CompuServe and the regional Bells, considering the amount of upgrading required to make a significant difference in their networks' performance. These companies also can get 10 cents to 15 cents per minute in circuit-switched long distance--easily undercut by most voice-over-frame-relay installations. Being new, not having conflicts with other lines of business and being able to build backbones with advanced switches from the start are definite advantages. Another approach is to toss out standards altogether and concentrate on the development of more efficient methods to handle voice from within the CPE through the backbone. Understandably, Infonet's Integrated Media Services (IMS), whose massive network service spreads to more than 30 countries worldwide, is taking this approach. It envisions better performance through its proprietary solution, Multi-Media Cell Technology (MMCT), developed jointly with Northern Telecom, which has said it will include the technology in its future products.

Making Your Server System Scale by Jay Milne Updated March 7, 1997