Innovative Access Solutions
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Dear Colleague, Multiservice
Ethernet Network Termination Units: The Need for Integrated TDM and
LAN Access over Ethernet Services
A clear demarcation point between the service provider and customer network is a prerequisite for reliable service delivery and SLA management. The "demarc" serves as the formal dividing line for defining network ownership and responsibility. Service providers frequently prefer to own the termination equipment at the customer premises to ensure reliable service delivery at the formal hand-off to the customer. Network Termination Units can vary from very simple to sophisticated devices. If the service provider is only looking to deliver Ethernet connectivity, a simple media converter that translates between the Last Mile fiber feed and the customer's internal network may be sufficient. If the provider wishes to deliver an Ethernet service with end-to-end control over the service - in or out of its footprint - an intelligent Ethernet Network Termination Unit (E-NTU) is called for. Finally, if the customer also needs support for legacy TDM services over the Ethernet connection, a multiservice NTU is required, providing service emulation over Ethernet. The network interface side of the NTU provides the physical termination of the service provider's fiber loop-fiber is typically used due to the high data rates customers demand. It must have the flexibility to accommodate a variety of data rates, fiber modes and wavelengths to ensure scalable and economical service reach from short distances to dozens of miles. In addition, the network interface needs to support a variety of remote OAM functions for ensuring maximum up time and eliminating costly "truck rolls" to diagnose and correct problems. These include remote diagnostics and loopback tests, fault propagation, in-band and out of band management, and remote software download and configuration. The user interface side of the Ethernet NTU enables service providers to offer critical capabilities such as flexible bandwidth granularity, CoS and VLANs-in effect allowing them to offer SLA guarantees to their customers. Certain applications, such as VoIP and circuit emulation, require prioritization to ensure dependable delivery of real-time traffic, especially in the presence of excess traffic from lower priority sources. The prioritization and associated rate limiting are typically controlled on a per-service and aggregate basis. VLAN tagging and VLAN stacking is needed in order to separate traffic sources from different customers, to provide uniqueness to VLAN numbering, and to ensure that service provider traffic doesn't interfere with user traffic. The Importance of OAM In addition to providing a clear demarcation and service/SLA management capabilities, a suite of OAM capabilities is required to manage the Ethernet services. These include fault indication and isolation, link monitoring, remote diagnostics and loop back tests, fault propagation, in-band and out of band management, and remote software download and configuration. These capabilities have been part of traditional TDM networks for years and are needed for TDM circuits delivered via circuit emulation as well. Successful carrier class Ethernet service delivery and management depends upon an equivalent set of capabilities. An integrated Ethernet and circuit emulation NTU provides the ability to have a single physical demarcation device at the customer premises, and enables remote diagnostics and management of both services using the same management system. Cellular Backhaul
As cellular network architectures evolve, operators are increasingly turning to Ethernet/IP transport for their Radio Access Networks (RANs) as well as for backbone traffic. In addition to leveraging the economies of Ethernet/IP, operators can choose from a larger variety of physical transports to eliminate their existing, expensive leased line circuits. Examples include dedicated fiber connections and point-to-point fixed wireless links. Since a very large percentage of the installed base of cell sites continue to use 2G technology, these sites generate TDM traffic that needs to be backhauled over the Ethernet connection. These sites also need Ethernet access for a variety of control and monitoring functions. Furthermore, as these cell sites migrate to 3G technologies, there will be a need to support Ethernet as part of the end user service offering. An economical multiservice Ethernet NTU is required to demarcate and manage the service as well as provide integrated access for both TDM and Ethernet cell site traffic. (See Time Warner Cable Selects RAD Data Communications for TDM Service over Ethernet.) Summary With Ethernet services becoming the metropolitan-and ultimately wide area-access technology of choice, coupled with the large installed base of TDM devices, a next generation multiservice NTU is clearly needed. This next generation multiservice Ethernet NTU must not only perform the traditional demarcation and OAM functions, but must also provide support for TDM and analog circuits via pseudowire/circuit emulation techniques. This critical pseudowire capability must meet strict performance requirements for a variety of applications such as cellular backhaul.
RAD Unveils Unique Enhancements for Maximizing Cellular Backhaul Traffic over Satellite Links
RAD Opens Office in Mumbai RAD Data Communications has announced the opening
of RAD India, its 23rd international office. Read the full
story Spain's National Railway Turns to RAD to
Connect Remote Sites over SHSDL Infrastructure Spain's Administrator of Railway Infrastructure
(known by its Spanish acronym ADIF) has chosen SHDSL modems from
RAD Data Communications to ensure the interoperability required
to connect remote sites and offices over existing copper infrastructure
to its broadband network. Read the full
story Time Warner Cable Selects
RAD Data Communications for TDM Service Delivery over Metro
Ethernet
Gmux-2000 Central Office TDMoIP
Gateway
Egate-100 Channelized Ethernet Gateway
Read about the challenge in providing cross-generation
access, discussed at length in an interview with RAD's CEO, Efraim
Wachtel. That and more are available in the latest version of RAD's
DataFlow newsletter, which you can read and then download for future
reference at http://www.rad.com/Home/0,6583,13751,00.html RAD Data Communications wishes you and your
families a happy holiday season. Sincerely, |
As the benefits of Ethernet networking in the
metro and wide-area have become clear, service providers are lining
up to meet the rapidly growing demand for Ethernet services. As with
any mainstream telecommunications service, providers need a reliable
way to deliver, control and maintain their offerings. Customers are
selecting providers that can offer SLAs tied to a variety of service
packages. 
Perhaps no application better illustrates the
power and capabilities of pseudowire/circuit emulation technology as
part of a multiservice Ethernet NTU than cellular backhaul. One of
the single largest expenses for cellular operators is the cost of
backhauling traffic from cell sites to mobile network aggregation
points. Frequently, operators rely on leased E1/T1 circuits from
incumbent carriers with whom they also compete. 
At GSM Africa 2005, RAD unveiled several unique
solutions for reducing carrier expenses by maximizing cellular backhaul
traffic over expensive satellite links. 
RAD Data Communications,
Inc. and Time Warner Cable, a division of Time Warner, have
announced the deployment of RAD's TDMoIP® pseudowire technology as
part of Time Warner Cable's rapidly growing Metro Ethernet service
offering in their Houston, Texas market. One of Time Warner Cable's
first customers for integrated Ethernet and TDM access was a large,
nationwide cellular telephone provider. With the Time Warner Cable
service, operators have access to high bandwidth, low latency
Ethernet connections for tower-to-MSC connectivity and use RAD's
IPmux pseudowire solution to transport the TDM traffic across the
same Ethernet link.
The Gmux-2000 is a modular carrier-class
TDMoIP gateway ideally located at large customer sites, points-of-presence
(POPs) and central offices of carriers wishing to transport a large
capacity of TDM traffic over packet-switched networks. 
The Egate-100 is a channelized
gateway for interconnecting TDM and packet networks. It aggregates
and switches Ethernet traffic to a single STM-1/OC-3 port, for up to
63 or 84 remote sites over E1 or T1 circuits respectively; or up to
126 remote sites over fractional E1/T1 circuits. The traffic is
combined into a channelized STM-1/OC-3 stream, and transmitted over
the packet network via the unit's Gigabit Ethernet
port.