Occam Networks Inc. of Santa Barbara, Calif. today introduced Ethernet Protection Switching (EPS) an Occam-developed technology that the company said gives Ethernet the resiliency of SONET networks with a 50 millisecond fail-over to a backup path in case of link or node failure.
With EPS, the Occam Broadband Loop Carrier (BLC) meets the "five nines" network availability required in public telecommunications networks, enabling carriers to take advantage of the cost savings and scalable bandwidth Ethernet provides.
EPS is available with Occam's BLC System, a complete Ethernet- and IP-based loop carrier that combines the functionality of a DLC, DSLAM, and media gateway to deliver broadband data and lifeline POTS from a single, converged access network, company officials also said.
Mark Rumer, Occam co-founder and chief technology officer, said in a statement, "The Occam solution uses standard Ethernet silicon and switching combined with our Ethernet Protection Switching to make networks using Ethernet transport as resilient as SONET networks, while alleviating the ring size and distance limitations of SONET. With EPS, carriers can also leverage the high bandwidth and low cost of Ethernet in the access and metro networks without compromising their voice and data services."
EPS offers several advantages over SONET technology, including greater deployment flexibility. With EPS, carriers can implement a variety of network topologies, including rings, star, and tree. There are no limits on network length or the number of nodes on each network, and EPS can operate over copper, fiber, or other transport media. With its support for a wide variety of media and network configurations, EPS give carriers maximum deployment flexibility that translates directly to lower deployment costs.
A key feature of EPS is its dynamic use of bandwidth, Occam also said. Unlike SONET, where protection links are idle and unused during normal operation, EPS uses all the available bandwidth of all facilities to dynamically distribute network traffic during normal operations. When there is a failure, all remaining bandwidth is used according to quality-of-service priorities.
EPS also offers several benefits not available in other technologies such as Resilient Packet Ring (RPR) and Rapid Spanning Tree Protocol (RSTP). EPS uses the standard Ethernet 802.3 MAC protocol, which is supported by all network equipment unlike RPR, which requires silicon changes. The RPR standard will not be complete before 2003, while EPS is available now. RSTP can detect link failures, but may not detect node or equipment failures, and RSTP makes inefficient use of access network bandwidth.
EPS operates over predefined primary and alternate transport paths, automatically switching to alternate paths on link or node failures. EPS segments traffic into pre-configured Path Groups. Each Path Group uses a heartbeat to ensure the link is operating properly. When a failure occurs, EPS automatically switches the Path Group traffic to a "live" link in less than 50 msec, guaranteeing support for delay-sensitive services like voice and video.
EPS Path Groups are created according to the 802.1q Virtual LAN (VLAN) protocol, and each Path Group may contain multiple VLANs. The access network is designed with overlapping Path Groups and with alternate paths for every node. The network is a "legal" Ethernet network, since none of the VLANs creates a closed ring, company officials added.
Occam also introduced the second generation of its Broadband Loop Carrier System (BLC), a complete loop carrier solution that delivers ADSL and lifeline POTS services from a single, converged access network.
The new system includes: the BLC 1200 Remote Terminal (RT), which integrates the functionality of a DLC, DSLAM, media gateway and copper/telephone line tester; the BLC 1240 Central Office Terminal (COT); and cabinets for outside plant deployment. Occam also announced support for integrated optical loop transport through Ethernet Protection Switching (EPS), an Occam-developed, standards-based technology that provides Ethernet transport with SONET-like reliability.
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