singing the praises of vpls

benefits include service transparency, QoS, scalability

TODAY’S ECONOMICAL CLIMATE REFLECTS the trend in decentralization of enterprise Ethernet networks that are geographically separated, yet require simple, flexible and broadband glue to interconnect them. The customer expects to have a single, scalable Ethernet pipe that will carry multiple services across multiple sites at the desired service level with maximum transparency of the provider network.

The typical example is headquarters and remote offices that are dispersed over a geographical metro area which requires LAN-like communication with a broadband connection. Such a scenario will be preferable with a simple Ethernet connection to the provider network and transparency of communication protocols to satisfy customer needs and to avoid overhead in installations.

Virtual Private LAN Service (VPLS) is a class of Layer 2 Ethernet VPN that allows connection of multiple Ethernet sites over MPLS private or metro networks. It emulates a LAN that provides transparency and full learning and switching capabilities with carrier- class scalability and service delivery.

VPLS embraces the same logical concept as the virtual LAN technology, but with evolution of carriers’ needs with scalability for literally millions of subscribers. VPLS is a carrier-class technology with service transparency, QoS connection, bandwidth scalability and financial argument. It utilizes all the above with the scalability and resiliency of IP/MPLS to carry transparent LAN services between metropolitan areas that standard Ethernet equipment cannot support. Its significant advantage is that at the connection between the provider edge and the customer devices, there is no IP interaction.

All customer sites in a VPLS service appear to be on the same LAN, regardless of their geographical location. Each customer has its own private VPLS service that is completely separated logically from other customers across the whole shared carrier network. VPLS allows an enterprise customer to be in full control of WAN routing policies by running the routing service transparently over a private or public IP/MPLS backbone. VPLS services are transparent to higher layer protocols, so that any type of traffic can be transported and tunneled seamlessly.

VPLS always offers Ethernet port handoff (customer demarcation) between the carrier and the customer router or a simple LAN switch allowing higher bandwidth service at a lower cost of deployment.

Ethernet is the choice of next-generation carrier networks, and it will be embraced with the arguments that dictate the financial and technological future.

Service providers understand that behind the demarcation point of the carrier network there are customers who want to be connected and who also want to be comfortable with the technology, price and service.

A typical customer understands Ethernet LAN technology and has a better understanding of the associated services than any other alternative (legacy services) offered traditionally by the carrier. This demands simplicity in connecting geographically distributed sites, starting from SOHO locations that use only workgroup networks, up to high-end enterprises with complex financial and real-time applications.

This simplicity is required to be manifested by pure transparency and the use of existing LAN infrastructure at the demarcation point to save the service provider the nightmare of workloads and equipment expenses such as IP-tunneling equipment and expensive routers that were previously required.

QoS management is a fundamental requirement of any customer converged network that carries voice, video and data over IP. VPLS networks use the tunneling technique, and the QoS function offers a flexible framework in which to convey customers’ traffic with corresponding service level agreement information over a carrier network with the QoS policy set. Service providers can leverage class-of-service technology to provide priority services and leverage rich QoS signaling protocols with bandwidth reservation technology providing connection-oriented paths for voice, video, and other mission-critical traffic over their networks.

VPLS can guarantee end-to-end QoS and preserve that capability as it scales.

This is a critical function that forces the Ethernet service to be adaptable and to offer lucrative applications.

Bandwidth profiles allow a service provider to bill on bandwidth usage and plan allocation of network resources. Bandwidth profiles enable a service provider to offer multiple service instances per variable, such as physical port, customer-defined Virtual LAN Tag, or a VPLS service. Among the significant benefits of the VPLS access service are price and flexibility, allowing customers to order onthe- fly bandwidth increments for multiple sites instead of being constrained by the traditional legacy services.

In a new network design, bandwidth services can reach arbitrary speeds for an offered Ethernet physical port and with desired VPLS rates for distributed sites.

Bandwidth can be provisioned in real time from 64kbps to 1 gigabit with 1kbps granularity to allow multiprofile independent offerings for different customer needs and prices.

Today, the motivations of CLECs and ILECs are cost-effective infrastructure and revenue growth with attractive new applications and prices. In fact, the main difference between the two is whether the network exists and its size.

Deregulation and increased competition make it imperative that ILECs and CLECs respond quickly to customer demands for new services. After all, time-to-market can mean the difference between new found revenue and lost opportunities. The challenge is to deliver those new services as cost effectively as possible, while keeping a tight control on capital expenditures. VPLS reduces the high cost of ownership typically associated with multiple services replacing non-scalable frame relay and ATM Layer 2 technologies.

Carriers can reduce training, maintenance and administration costs by migrating to Ethernet VPLS that reflects a network design adaptable for service providers for transparent LAN services without facing IP complications that were typically dealt with by ISPs. CLECs and ILECs are typically transport carriers and this is exactly what their business customer expects — to have transparent pipes in a WAN.

In addition to selling VPLS to business customers, some cable operators can use VPLS Instances to create separate multipoint networks for the dual purpose of offering broadcast video services and expanding into other business services.

The emerging VPLS auto-discovery standard, enabled at the provider edge and signaling its service capabilities, offers easy-to-use VPN membership allocation.

With auto-discovery, each VPLS Provider Edge (PE) discovers which other PEs are part of the same VPLS domain and discovers PEs when they are added or removed from the network. The auto-discovery VPLS service allows for a smooth and simple provisioning tool to connect customer sites and is easy to use, has fewer points of failure and enables mass deployment.

Service providers are closer than ever in achieving the goal of service convergence on their MPLS networks. VPLS is the ultimate nextgeneration access technology to enable smooth handoff between the customer LAN and the provider MPLS WAN core. The VPLS concept enables providers to realize tremendously high savings on cost in equipment and operations, and to shed light on new value-added services in access networks with profit assuring solutions.

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