Nokia Broadband's D500 a graceful ATM-to-IP DSLAM solution - 2002 Product of the Month - Evaluation

Telecommunications Americas, March, 2002

www.nokia.com

With all the hype surrounding the all-IP converged network, service providers and vendors have realized that migration likely will be a three-step evolution: ATM, a hybrid ATM/IP network and then ultimately all-IP. Since carriers are not only looking for a means to gain incremental revenue, but also to reduce capex and opex, Nokia Broadband Systems' D500 enables a build-as-you-grow approach with support for multiple network architectures.

Nokia labels each evolutionary step as high-speed Internet access (ATM); broadband media (hybrid ATM/IP); and finally full-service access (all-IP). Unlike current Internet data deployments that require several networks and are limited by fixed bandwidth and a lack of QoS and SLAs, the full-service access network is an integrated network over IP that will enable bandwidth-on-demand and customer control. To support this new network with richer broadband media services, there is a drive to integrate intelligence into the edge and access networks held in place by IP.

Building on its earlier D50, Nokia's D500 aims at the DSLAM market. 'Nokia has the opportunity to become a prime-time player in this market," said Erik Keith, broadband infrastructure analyst for Current Analysis. "In terms of DSL service deployment, the Nokia D500 will enable large carriers such as RBOCs, ILECs and PTTs, which are heavily invested in ATM-based network architectures, to deploy ATM-based DSL services and then migrate to all-IP network architectures at their convenience, without massive capex on new equipment."

As part of this evolution, the D500 can support IP multicast and IGMP, enhancing a full suite of DSL services including ADSL, G.SHDSL (single pair high-speed DSL), VDSL-supported DiffServ, RSVP, dynamic bandwidth allocation and control, and MPLS-based QoS. By integrating IP multicasting, the D500 helps service providers offer voice and multimedia services including video on demand, pay-per-view, video conferencing, broadcast TV and streamed audio.

Generally available in Q1, the D500 can support emerging standard broadband interfaces, including GigE, ATM UNI interfaces for Fast Internet access to higher bandwidth applications such as gaming and video conferencing. In addition, it supports VoDSL, VoIP, IP VPN and even POTS. On one line card, an operator can run ATM over ADSL, where they are receiving IP over ATM over DSL. In addition, the D500 can transition from IPv4 to IPv6 networks.

More importantly, the D500 can integrate seamlessly into an operator's access network via standards-based optical and electric trunks, tributary and line interfaces and existing OSS systems through the NetAct Broadband Element manager CORBA interface. NetAct for Broadband 3.0 gives operators a single system that aggregates fault, topology, inventory and configuration management functions.

One element that will set the D500 apart is density. With an 80-Gbps backplane, the D500 can support 912 DSL ports per shelf, 2736 ports per rack, and up to 720 lines per 19-inch ETSI rack. If configured in a remote site, more than 250 users connected to a single cabinet or basement can receive up to 3 Mbps to 6 Mbps of dedicated video channels, The system can scale from OC-3/STM-1 and OC-12/STM-4 to 100BaseT and GigE. With 2-Gbps links to every line card and Gigabit uplinks to the network, the backplane can morph from ADSL to VDSL bit rates and beyond. To scale the system, a carrier can insert line cards in the full shelf or a smaller four-slot product that allows 200 interfaces per box.

Built-in tributary interfaces enable carriers to build subtendered networks with a master DSLAM and a subtendered DSLAM. This subtendered DSLAM could be located at the same site to enable the carrier to use the same trunking interfaces into the network. An operator could have units at multiple locations to deploy a star or chain network configuration. It can support any fiber-to-the-X configuration from fiber to the exchange/CO, fiber to the building to fiber to the curb, enabling carriers to deploy VDSL to support broadcast video in a more cost-effective manner vs. a fiber ring. Part of the product roadmap calls for a VDSL street cabinet solution that uses Ethernet-based PON (passive optical networking).

"If you have a lot of VDSL customers, you are building a fiber ring that's quite expensive, but utilizing an EPON is a more cost-effective way to do it

with the promise to optimize that network speed," said Graham Ellis, Nokia Broadband's director of product management. "The IP mantra is clear, and we will be following EPON and Ethernet in the first mile, both of which allow an operator to remove a layer of cost and static tax of ATM by going to a more dynamic IP-enabled architecture."