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	Switching On Frame Relay SVCs February 22, 1999
		Good News About SVCs: What Our Lab Tests Reveal Using MCI WorldCom's frame relay SVC (Switched Virtual Circuit) service, we discovered the data-carrying capacity of SVCs to be identical to that of PVCs (Permanent Virtual Circuits). Measured by a Wandel and Goltermann DA-30C running the RTBench application, our throughput, loss and delay were indistinguishable whether using SVCs or PVCs. All circuits were configured with identical CIR and port speed (in our test, 32-Kbps CIR and 64-Kbps port). Call setup delays were measured at between 55 milliseconds (ms) and 65 ms, from SETUP to CONNECT at the originator, in a test network with one-way latency of 24 ms. These short-call setup times should have little effect on existing data applications, and will not introduce noticeable delays for voice or video calls. We selected Motorola's Vanguard 6560 for this test, which supports voice over frame relay and SVCs. We achieved natural ringing/dial tone response and audio quality in both PVC and SVC configurations. The 6560 also successfully interoperated with our Bay Networks ASN router in IP data applications.