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Luminous E200: Enlightened Transport for Ethernet: Page 5 of 5

RPR differs from Sonet in the way it deals with the rings. In a typical Sonet network, one ring is used for traffic, the second is protection against failure. This wastes up to 50 percent of the available bandwidth. RPR allows traffic to be placed on either ring. The traffic can be protected or unprotected--it doesn't matter. Either ring will fail over to the other in case of fiber outage. The E220 performs this failover exactly as advertised. This can double the amount of bandwidth available for both transmitting and receiving.

After consulting with the vendor, Luminous Networks, we would like to clarify that voice calls should not drop or be disconnected since the circuit is restored within 50 milliseconds which is the SONET standard accepted by carriers to prevent TDM voice calls from dropping during a failure.

Darrin Woods is a Network Computing contributing editor. He has worked as a WAN engineer for a telecom carrier. Send your comments on this article to him at [email protected].