High-availability in multipoint to multipoint Ethernet for the delivery of Triple Play servicesLuis Aguirre-Torres and Gady RosenfeldPhone: +1 408 392 9292, luis@corrigent.com101 Metro Drive, Suite 680, San Jose, CA 95110Ethernet has become the most prominent business opportunity for network service providers. During recent years, telecommunications service providers as well as multi-service operators (MSO) have began the migration towards Ethernet, replacing legacy transport and TDM customer interfaces. Either as a point to point or multi-point to multi-point service, Ethernet offers the perfect vehicle for IP-based content distribution, enabling services such as Voice over IP (VoIP), IP Television (IPTV) and Video on Demand (VOD). These services, at times offered as a bundled Triple Play service, require an infrastructure which is not only efficient to transport packet services, but also offers the levels of availability normally associated with traditional TDM transport networks.Several methods for providing high availability have been extensively studied and implemented by a number of system vendors, including spanning tree protocol, MPLS fast-reroute (MPLS FRR) and Resilient Packet Rings (RPR). Specifically, RPR has been demonstrated to offer the levels of availability required to meet the requirements for availability, delay and delay variation, independent of the number or combination of Ethernet services being delivered over the RPR infrastructure.Multi-point to multi-point Ethernet services are typically implemented using Virtual Private LAN Services (VPLS), which offers a common (virtual) broadcast domain for the delivery of broadcast and multicast services such as IPTV. While RPR, through wrap and steer protection, seems to offer a solution for equipment and facility protection, it does not provide a method for protecting against downstream (towards the transport network) unidirectional physical port failure, shown in the figure below as the interface port between the IPTV video server (at times up fronted with an L2 switch) and the RPR transport node. An efficient method to protect against this type of failures is VPLS Remote Fault Indication (VPLS RFI), which in combination with RPR, can guarantee the end-to-end service level availability service providers are contractually committed to provide to the end user.VPLS RFI enables the creation of dual VPLS domains: a primary (active) and a secondary (stand-by) VPLS domain. The RFI feature enables the unidirectional physical port fault indication to be propagated towards every member of the common broadcast domain created to deliver IPTV (or any other IP-based multicast or broadcast service). Upon the reception of an RFI generated after a server port failure, all traffic delivered over the active domain is switched to the standby VPLS domain.In this article, the benefits of combining RPR protection with VPLS RFI are described and compared to other alternative solutions. Specifically, it details the implementation aspects of such approach and the immediate benefits to network service providers relying on a multi-point to multi-point Ethernet infrastructure over RPR for the delivery of unicast, multicast and broadcast services such as Triple Play.Figure 1. Remote Failure Indication

© 2006 Optical Society of America

PDF Article