Access Network Convergence

In many service provider networks, voice and data services (primarily Internet access using dial-up services) are deployed using a TDM infrastructure where all traffic is routed through a Class 5 switch. As service providers looked for a way to more efficient means to offer data services, they looked at xDSL and Integrated Access Devices (IADs).

For IADs, two primary alternatives were available, they were TDM or ATM. ATM offered efficiencies unavailable with TDM and provided a starting point for packet-based access. Today in many service provider networks there has been an incremental evolution from TDM access to ATM access primarily to offer data services. This access network deployment model is shown in the diagram below.

Although this solution is more efficient than TDM, it is burdened with the ATM drawback of inefficiency when handling IP traffic, and the requirement for separate voice and data virtual circuits so the ATM infrastructure can segregate the traffic accordingly. Additionally, there remained a requirement for an interworking function (a VoDSL gateway in the diagram above) to bring the voice traffic back into the PSTN. These VoDSL gateways tended to be non-integrated with other network elements.

When the PurePacket™ solution is introduced in this scenario, it enables a service provider to move beyond TDM and ATM access technologies to an IP/MPLS access infrastructure. By taking advantage of the multi-service capabilities of the PurePacketNode®, a service provider can maximize service offerings while utilizing a more cost-effective unified access infrastructure.

The PurePacket solution is introduced into the network architecture diagram below.

PurePacketOUTburst® provides the IAD functionality and either a PurePacketNode® or a PurePacketCompact™ provide an access aggregation function. A PurePacketNode is shown in the picture. The difference between the PurePacket solution and an ATM or TDM solution, is that traffic is managed using MPLS Labeled Switch Paths (LSPs) rather than ATM virtual circuits or even dedicated TDM DS0 channels.

Because the PurePacket solution has been designed and optimized from the beginning with IP services in mind, it is more efficient than ATM in that it carries all traffic in packet format without additional cell tax overhead. This design is also applied to voice services, which are packetized at the IAD.

PurePacket's use of advanced traffic management techniques allow all traffic to be managed to meet service-specific requirements, such as low latency for voice or dedicated bandwidth for dedicated data service application s (eg. Committed Information Rate - CIR).

As can be seen above, PurePacket also provides an integrated VoDSL and Digital Loop Carrier (DLC) function for terminating TDM voice traffic to a Class 5 switch. The advantage of this solution is that it represents less equipment for a service provider to purchase. In keeping with the multi-service nature of the solution, the PurePacketNode forwards IP traffic onto a service provider's core network where it is routed to the Internet or a Private Network domain.

Completing the portfolio is the PurePacketOMS™ (Operations Management System) that provides a common management system for the entire PurePacket solution, as opposed to multiple management systems commonly associated with multiple product implementations. For a service provider, this translates into operational efficiencies in provisioning and configuring network elements as well as delivering new services.

As a next generation access network is deployed, what comes next?

The answer is the ability to leverage this next generation access network with an ongoing evolution of the core network and a migration of voice services to a packet solution. This is shown in the network architecture diagram below.

One key aspect of the PurePacket vision is the ongoing evolution of the core network to an MPLS-enabled network. Because an MPLS aware network is Layer 2 protocol independent, this can be built on top of either IP and ATM infrastructures. By utilizing PurePacket, a complete IP/MPLS solution can be deployed, from access to core.

Another key aspect of the PurePacket solution, is its ability to fit within a service provider's evolution path from the circuit switched voice services network (the PSTN) to a SoftSwitch, packet-based voice services infrastructure.

A SoftSwitch architecture can deliver enhanced revenues using a distributed architecture that allows each functional component to scale independently. This scaling ability will enable a service provider to cost effectively introduce enhanced IP services, enter new markets, or implement small- scale deployments. Yet this same architecture will scale to large market sizes and the requirements of larger customers (eg. enterprise) as their demand for services grow.

PurePacket provides next generation access to a SoftSwitch model as easily as it provides next generation access to the circuit-switched model, without equipment forklifts or replacements.