Review of the 21CN Architecture and Design Event on 3 April

Matt Beal set the scene by summarising the background to 21CN, the business drivers and the progress to date. He noted the event was very much aimed at the network design community of the Call Providers (CP’s) and that it would not be addressing products, timescales or systems in any detail.

Chris Bilton (Vice President Networks & ICT, BT) presented an overview of the 21CN architecture. He stressed that the full 21CN Target Architecture is a visionary view of the future which will require further developments in terms of standards, technology availability, and even commercial models. 

The architecture will continue to change and evolve to reflect the outcome of consultation with the Industry, regulatory changes and emerging technology. The architecture features a Converged Network based on IP, MPLS and Ethernet, commercial off-the-shelf operational support systems, an Intelligence layer that is mobile enabled, and an open applications layer enabling rapid service creation.

The 21CN design itself was introduced by Graham Blau (Chief Designer 21CN, BT) who said that the network is being designed to be carrier grade industrialised and scaleable with multi-vendor interoperability in each domain and layer. It will support multiple services, multiple Lines of Business and Communications Providers and deliver BT’s TSR commitments. The more detailed design was described in four parts, each emphasising the significant attention that has been given to resilience under various network failure scenarios. Graham stressed that in a number of places, the design had yet to be finalised and was subject to ongoing consultation with Industry on the products to be supported.

Access, Transmission and backhaul was discussed by Peter Bell (Chief Designer Access, Transmission & Ethernet Infrastructure, BT). He explained the different types of MSAN and the way they are connected to aggregate traffic over the backhaul transmission facilities to the Metro Notes. He showed examples of how the traffic would be re-routed under various network failure scenarios including complete node failures. 

James Appleton (Chief Designer IP/MPLS Core Infrastructure, BT) discussed Metro, Core & Interconnecting Transmission. He described the purpose and the interconnectivity of the components that make up a fully functional Metro/Core Node. Some of the components are specific to a particular type of traffic (eg the voice media servers) whereas others such as Ethernet switches are used for most traffic types.

i-Node & Layer 4 Voice Application fell to Richard Gillman (Chief Designer 21CN Voice/Multimedia Infrastructure, BT) He told the audience in more detail the components that make up the voice infrastructure. Particular attention is being paid to resilience (for example of the call servers which can handle up to 750,000 end-user lines). He noted the main difference from 20CNs, especially the separation of the call control (signalling) from the media components.

Service Mappings over 21CN was discussed by Jeff Deslandes (Chief Designer Voice/Multimedia Services & 21CN Common Capabilities, BT). He presented examples of the way 21CN will support and route in a resilient way various types of traffic – voice, broadband, Ethernet and TDM. He also showed some of the options being considered for a multi-service point of handover.

Graham Blau drew the design overview to a close, again emphasising the attention that is being given to resiliency.

If you would like to know more the presentations are available in full at www.btwholesale.com/consult21