Broadband Gear Report for May 18, 2007

Feature: Cable Envisions an Ethernet World

By Peter Green, Nortel

Ask any cable operator and they'll tell you, top priorities include controlling network operations, maximizing performance, and allocating bandwidth appropriately to the right services without losing money or customers. Cable operators' success in residential voice has triggered a large-scale, real-time, latency sensitive demand on the network. That same network now has to support an Internet service that is facing the dynamic bandwidth demand of Web 2.0 applications and the proliferation of video content. The deployment of SDV (switched digital video) and VOD is poised to place yet another variable bandwidth demand on the core infrastructure. This massive growth in residential service requirements is placing an unpredictable bandwidth demand on the core network for cable operators.

Business operations demand access to real-time, highly secure and always-available information systems. This has resulted in businesses requesting a stringent SLA (service level agreement) for commercial communication services. To address this requirement, the typical SLA now includes CoS (class of service) for traffic types, frame delay, frame delay variation, frame loss, availability, fault detection time and fault restoration time. For cable operators to grow revenues and profits, their core network must support the bandwidth and SLA demands of commercial services.

To accommodate bandwidth demand variability and stringent SLAs, the cable operator can take advantage of Ethernet based technologies, such as, IEEE 802.1Qay (Provider Backbone Bridges Traffic Engineered -- PBB-TE), IEEE 802.1ag (Continuity Fault Management) and ITU-T Y.1731 (Performance Measurement).

Cable operators can address the business requirement for stringent SLAs through the utilization of PBB-TE in the core Ethernet network. PBB-TE is an address-based connection-oriented network technology, which delivers a deterministic service between customer end points. PBB-TE is address-based in that the backbone source address (B-SA) and backbone destination address (B-DA) is the unique identifier that is maintained throughout the network.

These addresses, in combination with a backbone VLAN ID (B-VID), allow for the implementation of traffic engineering rules that can be observed throughout the network. This connection-oriented nature of PBB-TE allows for the creation of pinned paths through the network. These pinned paths with resource allocation allows the cable operator to guarantee CoS with specific end-to-end frame delay and frame delivery ratio. To ensure connection availability, fault detection time and fault restoration time, equivalent protection paths can be defined. For example, to achieve a 50 ms fault restoration time, IEEE 802.1ag continuity check messages (CCM) can be sent in 10 millisecond intervals. Failure to receive the CCM causes both ends of the path to switch to the protection path.

While IEEE 802.1ag focuses on connectivity measurements, the ITU-T Y.1731 standard is focused on end-to-end performance management metrics. The standard defines the parameters for measuring and reporting the service metrics of frame delay, frame delay variation, frame loss and availability.

These performance measurements can be applied to end-to-end commercial services as well as the core infrastructure supporting residential services. When combined with the performance management of individual network elements, a top-level performance management system is able to resolve a comprehensive view of the health of the core infrastructure. With this service level detail for both commercial and residential service, the top-level operations, administration and management (OA&M) system is able to maximize performance while keeping costs in check.

Ethernet has emerged as a network and service infrastructure that is high on quality and low on cost. With technology standards, such as IEEE 802.1Qay, IEEE 802.1ag and ITU-T Y.1731 now a part of the Ethernet solution, cable operators have capabilities essential for their operations, including a robust security framework, a common set of network management functions and common service assurance and delivery mechanisms. Cable operators can benefit from the added flexibility, reliability and predictability to deliver both residential and commercial services over a common core infrastructure with best in class OA&M.

Peter Green is a cable MSO business development and solutions director for the Metro Ethernet Networks business unit of Nortel (www.nortel.com). During his eight years at Nortel, he has held a variety of positions, including solutions architecture leader and carrier services planner.