All carrier grade engineered networks embody certain characteristics which remain as relevant to next generation networks as they do today. They include:
Flexibility: This is the ability of a network to flex its capacity and connectivity to meet the different needs of users and support the different product types. IP is more flexible than traditional circuit switched networks. This is because it can handle communications previously carried by multiple, bespoke networks. Based on IP, 21CN is multi-service - a single network infrastructure supporting voice, data, internet and video services. In an IP world, services are applications - so voice becomes one of many applications running on a common platform and the systems, services and management processes are shared.
Efficiency: This is the ability of a network to meet the needs of its users in a cost effectively and hardware-efficient manner. Adopting IP as the common transport method in 21CN will bring efficiencies in the delivery of products and services and in the operational systems which support them.
Reliability, service continuity and resilience: This is the ability of a network to consistently meet its service level agreements, offering continuity of service. Good reliability is achieved by good design using high quality components coupled with a high level of resilience - the ability of a network to continue to provide normal (or near-normal) service even if faults occur through diverse routing which enables, for example, an alternative node to process the calls of another one.
The resilience of 21CN has been designed to be equivalent to that of today's networks with opportunities taken to improve it where possible. 21CN has both physical and logical resilience. Its significant physical resilience is afforded by multiple physically separate paths in, out and between nodes, plus the replication of key devices, for example, dual power supplies. The logical resilience is provided by protection switching and alternative routing protocols between equipment - enabling communications to be automatically switched to an alternative route if necessary - and service is also supported by equipment at discrete locations. For example, each MSAN in 21CN will have a primary and secondary parent Metro Node and a primary and secondary call server. The introduction of the single 21CN IP-based network will result in physically a simpler network which will simplify the service management enhancing reliability and resilience.
Evolution: Network technology is constantly changing and improving allowing new market and commercial opportunities to be developed. Networks therefore need to be capable of evolution to accommodate new technologies - a principle taken into account when designing new networks. Network designers work closely with suppliers and the standards community to build an appropriate level of future proofing into the infrastructure. Looking back we can see four telecom infrastructure eras - namely:
manual switch boards and heavy copper cables
analogue communications with Strowger auto-mechanical switching
digitalisation
overlay of service specific technologies including ATM and IP.
These are telecoms revolutions and with the introduction of 21CN we are witnessing another. Between these step changes are periods of refinement and enhancement where networks evolve to meet market requirements.
Quality: Voice quality on 21CN will be the equivalent or better than PSTN as
the use of Multi Protocol Label Switching (MPLS) prioritisation technology will ensure voice calls are given precedence over less time critical communications such as email. By employing state-of-the art technology, helping to define appropriate industry standards and through rigorous assessment of voice quality, BT is seeking to ensure that voice quality on 21CN is optimised. The bottom line is that no-one should notice any difference.
Security: In a telecommunications context 'security' is the ability of a network to resist attack from, for example, software virus and hackers - and also includes secure data transmission and the physical security of our buildings and infrastructure. For some the word internet can raise concerns about security. But with 21CN calls are not going over the internet. They will be carried on our dedicated high capacity IP network. But let's take a closer look...
The internet is a term widely used to describe the public network that we connect to when accessing the world wide web. Intranet and extranet are terms used for private secure internet-type networks. However, IP is something different: it is a protocol - a language, a set of rules - that computers use to talk to each other and exchange data.
It is the way an IP network is set-up that defines if it is public, private, open or secure. BT and other communications providers use IP today for data networks. Finance and defence information networks where security is paramount use IP. 21CN will be an IP-based network.
BT deploys security today in the physical and logical world, to protect all our network infrastructure, our services and the confidentiality and integrity of our customers' data. These security measures use technology combined with operational processes, procedures and standards to protect and monitor our IP networks - and we have dedicated, expert teams and control processes to identify and respond to suspicious activity. Building on these measures and our vast experience in both traditional networks and the IP-based networks we already operate, 21CN will meet the high standards that BT provides to our customers today.