While the Local Area Network (LAN) has seen a rapid convergence toward a single technology and protocol, namely Ethernet, wide area connectivity has gone through some interesting evolution for business customers over the last 20 years.Internet Protocol (IP) over Ethernet on the LAN has been the de facto standard for applications for business customers and consumers alike. In order to provide connectivity across a wide area, IP/Ethernet was traditionally encapsulated over a plethora of OSI Layer 2 protocols on the WAN; from X.25 in the 1980s and Frame-Relay in the early ‘90s, to ATM in the mid-to-late ‘90s, and in the last decade or so, Multiprotocol Label Switching (MPLS).However, the realisation that virtually all business traffic originates and terminates on an Ethernet LAN has forced a continued scrutiny of the appropriateness of these WAN protocols, because none of them fundamentally addresses the business needs of being simultaneously reliable, efficient, high-quality, manageable and cost-effective in transporting what is essentially Ethernet LAN traffic. More recently, with the advent of hosted solutions or managed services offerings from service providers, many businesses have seen the operational benefits of handing over the management of their WAN to a service provider, with clearly spelled-out Service Level Agreements (SLAs). For the service provider, these managed services and SLA offerings drive significant incremental revenue above and beyond simple bandwidth connectivity services.That said, SLAs also represent a significant risk to the service provider; any SLA that is not met could result not only in lost revenue but, potentially, monetary claims against the service provider. That being the case, many service providers continue to use traditional WAN connectivity methods such as Synchronous Digital Hierarchy (SDH) for its superior reliability, quality and manageability, to the detriment of efficiency and cost-effectiveness.Technology enablersWith the tremendous explosion seen globally in bandwidth demand, driven largely by new and exciting applications and devices for businesses and consumers alike, the search has continued for a WAN connectivity solution that offers all the benefits of being reliable and efficient, while also meeting the required levels of quality, manageability and cost-effectiveness.A number of technology innovations in recent years saw Ethernet emerge as the de facto OSI Layer 2 WAN protocols. It not only offers all the benefits of existing protocols, but also has an attractive price point thanks to the ubiquitous and commoditised nature of Ethernet networking hardware, and without any of the inefficiencies of legacy protocols.The technology innovations extend and leverage open industry standards for Ethernet and IP as defined by standards bodies such as the International Telecommunications Union (ITU), the Institute of Electrical and Electronic Engineering (IEEE), and the Internet Engineering Task Force (IETF). Specifically, the innovations are defined by a number of new open industry standards:
- IEEE 802.1Qay, commonly known as Provider Backbone Bridging – Traffic Engineering (PBB-TE)
- IETF Multiprotocol Label Switching-Transport Profile (MPLS-TP), though currently still in draft-standard status
- IEEE 802.1ag, commonly known as Connectivity Fault Management (CFM)
- ITU-T Y.1731, commonly known as Performance Management (PM)
- ITU-T G.8031 and G.8032, Ethernet linear and ring protection
When combined with standards-based Ethernet, these new Carrier Ethernet standards help elevate simple Ethernet OSI Layer 2 transport technology that offers operational efficiencies across the wide area. In addition to these innovative technology building blocks, the Metro Ethernet Forum (MEF), a defining body for Carrier Ethernet involving global industry alliances comprising more than 150 organisations, has defined a number of service constructs that improve upon traditional service delivery topologies, for example, with the definition of services such as E-Line – a point-to-point service; E-LAN – multipoint-to-multipoint service; and E-Tree – a point-to-multipoint service. The MEF’s implementation agreements ensure that vendor solutions not only adhere to the technical requirements of a Carrier Ethernet solution, but also to the service delivery standards and multi-vendor interoperability.Carrier Ethernet brings together the benefits of many legacy protocols without many of their drawbacks. In evaluating Carrier Ethernet as a solution for your business, one should ensure the following key attributes in the chosen solution:Efficiency – Like many technology buzz phrases, ‘Carrier Ethernet’ can be somewhat ambiguous since non-Ethernet based WAN technologies such as SDH or MPLS can also deliver Carrier Ethernet services. However, these do not operate anywhere near as efficiently as a native Ethernet solution and will ultimately result in poor bandwidth utilisation and operational challenges.Reliability – One of the most important foundations of a true Carrier Ethernet solution is reliability. There are a number of aspects to this, for example, equipment reliability, but more significantly the ability to self-heal during network outages. The traditional benchmark for network reliability during outages is the restoration of services on backup paths within 50 milliseconds. The vendor solution chosen must support standards mentioned above such as PBB-TE and ITU-T G.8032, in order for the Carrier Ethernet solution to be truly reliable.Quality – Another key attribute is the ability to support Quality of Service (QoS). The solution chosen should support guaranteed QoS settings in addition to more sophisticated tagging and label manipulation features that are customisable and granular in order to improve quality and enforce SLAs.Scalability – One of the most apparent characteristics of current bandwidth demand is its almost predictable exponential growth. It’s vital to ensure the chosen solution not only supports your immediate needs but can scale with your needs over the next couple of years. Port types of Gigabit Ethernet today are expected to become passé as we see the demand evolve to 10GE and even 100GE in the near future.Interoperability – As the Carrier Ethernet solution is expected to co-exist in a heterogeneous end-to-end network, it’s important to ensure multi-protocol support and standards adherence to ensure interoperability. For example, solutions that support not just Carrier Ethernet access but also MPLS, for IP backbone connectivity, are essential.Manageability – With hosted solutions or managed service offerings, SLAs become a vital element of the service, so manageability is a key requirement. You should ensure your chosen solution supports technology such as Connectivity Fault Management and Performance Management, in addition to basic element-level management of Carrier Ethernet devices. Deployment agility – One key attribute that is perhaps most required by service providers is deployment agility – the ability to deploy a Carrier Ethernet solution quickly and cost-effectively. Many Carrier Ethernet solutions available in the market demand significant expertise and time to deploy; therefore ensuring the chosen solution has plug-and-play attributes is an important criterion.What’s in store for the future?There are a number of additional exciting developments in Carrier Ethernet. With wireless network technology evolving toward Long Term Evolution (LTE), the need for Carrier Ethernet becomes even more important. However wireless network solutions in general, and LTE in particular, have strict operational requirements around network synchronisation and timing; emerging standards such as Synchronous Ethernet (ITU G.8262), and IEEE 1588v2 are supported on these new Carrier Ethernet solutions.Looking ahead, Carrier Ethernet has a bright future as the ultimate universal standard for OSI Layer 2 connectivity that is dynamic, adequately addresses the needs of businesses, and is cost- effective.