Handbook of Local Area Networks, 1998 Edition:LAN Interconnectivity Basics Click Here! Search the site:   ITLibrary ITKnowledge EXPERT SEARCH Programming Languages Databases Security Web Services Network Services Middleware Components Operating Systems User Interfaces Groupware & Collaboration Content Management Productivity Applications Hardware Fun & Games EarthWeb sites Crossnodes Datamation Developer.com DICE EarthWeb.com EarthWeb Direct ERP Hub Gamelan GoCertify.com HTMLGoodies Intranet Journal IT Knowledge IT Library JavaGoodies JARS JavaScripts.com open source IT RoadCoders Y2K Info Previous Table of Contents Next Voice Over Frame Relay The ability to carry voice over frame relay in a standard way would allow for a scaled-down form of integrated access to be offered by carriers. The pending specification from the Frame Relay Forum describes support for standard voice compression algorithms for interoperability, the use of proprietary algorithms for reduced bandwidth usage, and signaling requirements to support connection to PBXs, key systems, and telephone equipment. With or without standards, voice over frame relay offers cost savings for networks that span regional or international boundaries and therefore suffer from high long-distance charges per minute. Only a few access vendors have or have announced this capability;they include ACT, FastComm, Micom, Memotec, and Scitec. It is anticipated that the standardization of the feature will cause switch and PBX vendors to follow suit with interoperable products, allowing carriers to support the feature in their service offerings. Voice over frame relay is illustrated in Exhibit 3-4-8. In this example, several remote sites have LANs and other data applications sharing access to the frame relay network with compressed voice and demodulated fax traffic. The voice/fax traffic is homed to a PBX, which supports many telephones and fax machines. The remote telephones and fax machines appear to be extensions off the PBX. The voice/fax call across the frame relay network is toll-free—that is, no long-distance charges are accrued. If allowed in the region where the equipment is located, connections to a public switched telephone network may also be supported. Exhibit 3-4-8.  Voice Over Frame Relay Fax traffic must be demodulated and the fax protocol spoofed to pass the fax traffic with minimal bandwidth used. When demodulated, the fax traffic will only require from 4.8K to 9.6K bps, typically. Otherwise, it might require as much as 32K to 64K bps, as seen in the typical public switched telephone network environment. Frame Relay Feeding ATM Whereas ATM for LANs in campus environments is just beginning to be deployed in a meaningful way, most carriers have not yet fully deployed nationwide or international networks to support ATM over the wide area. At present, frame relay appears to be the WAN service of choice. Above T1/E1, through T3/E3, and at higher speeds, ATM would appear be the service of choice in the future, assuming availability and cost-effectiveness of services and the emergence of new business applications that truly require the higher bandwidth of ATM. Frame relay should become an excellent feeder technology for medium to large networks using ATM at the core. Some carriers have already deployed their frame relay service using ATM or synchronous optical network (SONET) equipment as a backbone or core network. Exhibit 3-4-9 illustrates frame relay to ATM interworking. In this example, both network and service interworking between frame relay and ATM are used. The sites on the left of the exhibit (site A and site D) are sending frame relay traffic over ATM, which arrives at site B as native ATM traffic. This is service interworking. Sites A and D are also able to communicate with site C, sending frame relay traffic through the ATM network, which arrives as frame relay. This latter situation is network interworking. Exhibit 3-4-9.  Frame Relay to ATM The interworking functions can reside in the frame relay or ATM networks, or in other devices, such as when a frame relay workstation is, for example, connected to an ATM access device. Its traffic is translated to ATM, or sent through ATM, depending on which site it is sent to. SUMMARY The growing deployment of frame relay products and services will guarantee frame relay a place in the networking hierarchy. The ease of implementation of frame relay, as compared with ATM, will allow equipment vendors to provide frame relay capable ports at a lower cost than just about any other networking protocol available today. Previous Table of Contents Next Use of this site is subject certain Terms & Conditions. Copyright (c) 1996-1999 EarthWeb, Inc.. All rights reserved. Reproduction in whole or in part in any form or medium without express written permission of EarthWeb is prohibited. Please read our privacy policy for details.