Platforms ready for VoIP media gateways - Embedded.com

Platforms ready for VoIP media gateways

The converged or next generation network will have instead of distinct networks for voice, video and data these merged and managed into a single packet-based network. This should mean that a combined network is easier to manage and build.

Existing time division multiplexing (TDM) circuit-based networks were originally thought to be suitable as they would carry streams of voice traffic but are not efficient at handling data traffic that comes in bursts.

The alternative is to provide bridges between the various networks and this is the job of the the Media Gateway.The latest addition to the Comstruct product line from Motorola Computer Group is an Integrated Gateway Platform (IGP) series, a range of application-ready platforms designed to speed up the development of OEM media gateways.

Each model in the ComStruct IGP series is an open-standards based, integrated and fully tested system which contains all the components required of a media gateway. This means that a telecom OEM has only to add and test its application.

The ComStruct IGP series is designed to scale from 120 ports to 20,000 ports per shelf. The first model is the ComStruct IGP1000 which provides up to 360 ports of compressed VoIP.

Integrated into a CompactPCI chassis are an application processor board, multiple packet voice processor boards, a high availability operating system and Motorola's FACT-MG gateway development software, which includes full resource management.

The ComStruct IGP1000 also includes example applications to allow customers to evaluate voice quality and stability, investigate technology such as session initiation protocol (SIP) or simulate larger installations. Future models in the ComStruct IGP series will build on Motorola's product range, including the MXP multi-service packet transport platform, in order to address the deployment of broadband access gateways, media service platforms, IP and ATM trunking gateways, core network switch replacement and 3G wireless media gateways.

A Media Gateway (MGW) is the entity that translates between networks of differing standards. It provides conversion of streamed media formats such as voice or video and manages the transfer of information between the different networks. As such, it is the equivalent to either a local or transit switch in the switched circuit network.However, converting from any format to any format would be a rather ambitious goal making it difficult for both equipment users and vendors to focus on the key issue of interworking. To help facilitate this, the Internet Engineering Task Force (IETF) considered the most common types of gateway functionality and created specific feature-sets these gateway types should offer.

The most common gateway types are:

Residential Gateways – used in a small office or home office to connect typically less than 10 analog devices to an IP network.

Access Gateways – connect user network interfaces (such as ISDN or traditional analog services) to a VoIP or voice over ATM network. As such, they will typically terminate TDM call signaling and pass this information to a Media Gateway Controller or Softswitch for call control decisions to be made. Access gateways might consist of less than 100 channels today but with some increase in density expected over the next few years.

Trunking Gateways – gateways that interface between the PSTN telephone network and the IPbased network (or ATM network). Such gateways typically manage a large number of digital virtual circuits and TDM bearer circuits with signaling carried on a separate path (through a signaling gateway).

Network Access Server (NAS) – a specialized form of the Access Gateway designed to terminate modem calls or HDLC connections and provide data access to the IP network.

Some of the core features are the same for all media gateway designs, but additional features such as local network services, make the media gateway a complete and customisable design.

According to Motorola a fundamental issue in ensuring that a gateway platform will take an OEM from development to deployment is a software compatible roadmap. The vendor must be able to provide the customer with a roadmap for the product that they are using today.

Motorola says that from concept to a full release for full gateway development would typically take 12 to 18 months with the bulk of the work bringing together the individual pieces and making them all work together. Starting with an integrated platform could reduce this by up to 9 months.

The ComStruct IGP 1000 comes in a 3U 19in rack mount enclosure. The enclosure has a 200W power supply, alarm panel, one master and four peripheral slots with H.110 full hot swap and NEBS level 3 compliance. The enclosure contains an Intel Pentium III based application processor board with 512Mbyte of memory and on-board disk drive. There are multiple packet voice processing boards and an optional IP integration switch.

The pre-installed software includes Red Hat Linux operating systems with high availability extensions and an object oriented API with multiple board resource management.

For packet network termination there is multiple 100BaseT Ethernet with active and standby configuration. A dual Gigabit Ethernet has the optional IP switch and there is support for quality of service (802.1p) and VLAN (802.1Q).

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