nternet and intranet traffic. technologies (Frame Relay, IP, and ATM), Frame Relay is The lowest QoS, Available/Unspecified Frame Rate, is the most widely deployed. It is commonly used in cor- used for e-mail, file transfer, and residential Internet porate data networks due to its flexible bandwidth, traffic. In addition, the VFRAD can be configured to widespread accessibility, and support of a diverse traffic assign less sensitive traffic with a Discard Eligibility (DE) mix and technological maturity. bit. These frames will be dropped first in case of network Frame Relay service is based on PVCs. This service is congestion. appropriate for closed user groups and is also recom- mended for star topologies and predictable performance Fragmentation needs. VoFR is a logical progression for corporations al- ready running data over Frame Relay. VFRADs incorporate fragmentation schemes to improve VFRADs integrate voice into the data network by performance. Data packets are divided into small frag- connecting the router, SNA controller, and the PBX at ments, allowing higher-priority voice packets to receive each site in the corporate network to the Frame Relay the right-of-way without waiting for the end of long data network. transmissions. The remaining data packets in the data stream are momentarily halted until the voice trans- Many VFRADs employ sophisticated techniques to overcome the limitations of transporting voice over the mission gets through (see Figure 3.2-5). The downside of fragmentation is that it increases the Frame Relay network without the need to add costly bandwidth. number of data frames, thereby increasing the number of flags and headers. This also increases overhead as well as reduces bandwidth efficiency. RAD's FR+ application VoFR prioritization provides an enhanced fragmentation mechanism that As we know, Voice is a real-time application. Prioritiza- fragments data frames only in cases where voice packets tion over any other packet is mandatory to have a suc- arrive at the switch during a data t