Citizendia
Your Ad Here

The 21st Century Network (21CN) programme is the network transformation project of the UK telecommunications company BT Group plc. BT Group plc (formerly British Telecommunications plc) which trades as BT (ˌbiːˈtiː bee tee) (previously known as British Telecom and still It will see the UK incumbent's telephone network move from the present AXE/System X Public Switched Telephone Network (PSTN) to an Internet Protocol (IP) system. The AXE telephone exchange is a product line of circuit switched digital Telephone exchanges manufactured by Ericsson, a Swedish telecom company System X was the name of the UK's first national Digital Telephone exchange system The public switched telephone network ( PSTN) is the network of the world's public circuit-switched Telephone networks in much the same way that the The Internet Protocol ( IP) is a protocol used for communicating data across a Packet-switched Internetwork using the Internet Protocol As well as switching over the PSTN, BT has revealed plans to deliver many additional services over their new network, such as on-demand interactive TV services.

BT has stated that it will accrue annual savings of £1 billion when the transition to the new network is complete, with over 50% of its customers transferred by 2008. Capital expenditure is put at £10 billion over the next five years, this being 75% of BT's total capital spending plans in that period.

Contents

21CN Architecture

The new network is based on an architectural model of 5 network nodes. These are:

Premises

The premises node includes residential, Small-Medium Enterprise (SME) and Enterprise. The presumption is that all these will have high speed connections to the network, delivered over copper (in the form of ADSL or other DSL technologies) or over fibre, as either PON or direct fibre in the case of large enterprises. Asymmetric Digital Subscriber Line ( ADSL) is a form of DSL, a data communications technology that enables faster data transmission over Copper Telephone A passive optical network ( PON) is a Point-to-multipoint, Fiber to the premises network architecture in which unpowered Optical splitters The sole exception to this presumption is for legacy PSTN, where provision will continue to be made for analogue voice.

Access Node

21CN introduced the concept of the Multi-Service Access Node (MSAN). A multiservice access node (MSAN is a device typically installed in a Telephone exchange (although sometimes in a roadside Serving area interface cabinet which connects This logical node takes the various access technologies (mentioned above) and, where possible, aggregates these onto a single backhaul network technology. In a hierarchical telecommunication network the backhaul portion of the network comprises the intermediate links between the core or backbone of the network and the small subnetworks This includes converting analogue voice into Voice over IP (VoIP) using the MSAN as a Media Gateway (MGW). Voice-over-Internet protocol ( VoIP, vɔɪp is a protocol optimized for the transmission of voice through the Internet A Media Gateway, abbreviated MGW acts as a translation unit between disparate telecommunications networks such as PSTN; Next Generation Networks; 2G The aim is to implement a few hundred access nodes. Note that these will not have any IP routing capability, but will essentially be Layer 2 Ethernet devices. The Internet Protocol ( IP) is a protocol used for communicating data across a Packet-switched Internetwork using the Internet Protocol The Data Link Layer is Layer 2 of the seven-layer OSI model. It responds to service requests from the Network Layer and issues service requests to the Ethernet is a family of frame -based Computer networking technologies for Local area networks (LANs

Metro Node

The backhaul network will terminate on the metro nodes. At this point the IP-based services will be implemented, and the metro nodes are the first location where IP traffic is routed. Call control (via a softswitch or an IMS CSCF) will be implemented here, although the softswitches and the IMS components won't be described as a part of the metro node - they are parts of the iNode. A softswitch is a central device in a Telephone network which connects calls from one phone line to another entirely by means of software running on a computer system The IP Multimedia Subsystem ( IMS) is an architectural framework for delivering Internet protocol (IP Multimedia to mobile users The metro nodes are also Provider Edge (PE) routers in MPLS terminology, encapsulating the IP traffic in MPLS tunnels for transmission over the core. MPLS redirects here For other uses see Mpls In Computer networking and Telecommunications, Multi Protocol Label Switching The aim is to implement around 100 metro nodes.

Core Node

The core nodes are MPLS switches, with the MPLS traffic carried over optical (DWDM) transport. In Fiber-optic communications wavelength-division multiplexing ( WDM) is a technology which multiplexes multiple optical carrier signals on a They are completely unaware of customer IP traffic, and only switch based on MPLS tags (all customer IP traffic is encapsulated with an MPLS header by the Metro node PEs). Native IP is only used by the Core nodes for protocols such as MP-BGP, an IGP, LDP, and RSVP to exchange routing and label information between all Core and Metro nodes. The aim is to have approximately 10 core nodes.

iNode

The iNode is the name for the logical node that provides the control for the services implemented using the other 4 nodes. BT has announced that it intends to create an IMS based iNode capability, although its initial PSTN replacement will not be an IMS implementation. The iNode will implement a set of standardized functions - common capabilities - that deliver layered services. Common capabilities include session management, authentication, profile, address book, presence and location. Combinations of these capability primitives will be used to deliver different service types and functionality.

The iNode is built upon the BYB501 AXE10 TSS (Telephony Softswitch Server) and is currently using the grade 50 HP based processor (APZ 212 50) as well as the IS-Blade in the APZ logic. After extensive field testing and countless iNode soft revisions in the South Wales Pathfinder area all current logical and intelligent network services now operate in conjunction with the existing PSTN and the MPLS network.

Suppliers

In April 2005, BT announced that it had selected 8 suppliers for its 21CN roll out. These were:

The fact that Marconi received no major 21CN contract was a surprise to commentators and sent the company's shares tumbling. is a Japanese company specializing in Semiconductors Computers ( Supercomputers Personal computers, servers, Telecommunications Huawei Technologies Co Ltd ( in Shenzhen, Guangdong, People's Republic of China is the largest networking and telecommunications equipment supplier Alcatel-Lucent is one of the world's biggest industry players in Telecommunications that provides hardware software and services to Service Providers Enterprises and Lucent Technologies was a technology company composed of what was formerly AT&T Technologies, which included Western Electric and Bell Labs. Ciena Corporation Ciena Corporation is a supplier of communications networking equipment software and services that support the delivery and transport of voice video and data Ericsson ( Telefonaktiebolaget L M Ericsson) () one of the largest Swedish companies is a leading provider of telecommunication and data communication systems telent plc is a Radio, Telecommunication, and Internet systems installation & services provision company. An example of analysis before BT announced the winners of contracts is Dresdner Kleinwort Wasserstein's: "[Marconi is] so advanced with its products and so entrenched with BT Group PLC that its selection looks certain. Dresdner Kleinwort (DKIB is the Investment bank of Dresdner Bank AG, part of the Allianz Group since July 2001 (Dresdner Bank AG is currently being "[1]

Implementation

BT has announced that its initial roll-out of the network will take place in the South Wales area, around Cardiff, beginning in November 2006. This will initially involve the migration of 350,000 customers from the old PSTN to the new network. It has announced that it expects 50% of its customer base to have been migrated by 2008, and the migration to be "substantially complete" by the end of the decade.

BT will be transferring customers on its IPstream product in the West Midlands area (circa 650 exchanges) to the 21CN equivalent IPstream product between October and December 2007 before transferring them over to ADSL2+ products in early 2008. IPstream is the most highly-used Wholesale Broadband Internet service in the United Kingdom[http //www

In October 2006, the first call was made on a migrated test line between 21CN and today's networks.

On 28 November 2006 the first 100 voice customers in Wick were switched onto 21CN. For the town in Argentina, see 28 de Noviembre. Events Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Wick (Y Wig is a small Village in the Vale of Glamorgan in Wales, situated about two Miles from the coast [2]

On 14 September 2007 BT announced that Entanet, BT Wholesale and BT Retail were chosen for the first service trial in the West Midlands[3]

BT also plans to launch ADSL2+ services from early 2008. Events 81 - Domitian becomes Emperor of the Roman Empire upon the death of his brother Titus. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Entanet International is a British Wholesale ISP and is a member of the Internet Service Providers Association History 1996 BT Wholesale is a division of BT Group responsible for the wholesale leasing of PSTN lines Broadband services and other telephony services to retail customers BT Retail is the consumer sales arm of Britain's BT Group. BT Retail is responsible for selling PSTN, Broadband, BT Vision, etc to consumers The West Midlands is a Metropolitan county in western central England with a population of 2591300

Criticism

The plan has come under some criticism, mainly due to BT's plans for broadband internet access services. Broadband Internet access, often shortened to just Broadband, is high-speed Internet access—typically contrasted with dial-up access over a Modem BT's main plan for providing internet access is to upgrade their dslams to ADSL2 in the exchange. A Digital Subscriber Line Access Multiplexer ( DSLAM, often pronounced dee-slam) allows Telephone lines to make faster connections to the Internet ITU G9925 is an ITU ( International Telecommunication Union) standard also referred to as ADSL2+ or ADSL2Plus. This has been controversial because ADSL2+ is already an old technology and is limited to 24Mbit/s downstream,[2] and will be even more dated by the time 21CN is completed (Around 2010), leading to criticisms that BT is not future proofing their network. ITU G9925 is an ITU ( International Telecommunication Union) standard also referred to as ADSL2+ or ADSL2Plus. In telecommunications Bit rate or Data transfer rate is the average number of Bits characters or blocks per unit time passing between equipment in a data transmission For the film see 2010 The Year We Make Contact. For the book see 2010 Odyssey Two. Critics argue that fibre to the home would be more appropriate, which would mean replacing the current copper wire which supplies individual homes (the "last mile").

UK security agency CESG has privately voiced concerns over the decision to use Huawei to provide some of the equipment, citing security concerns, as much UK government, intelligence and military traffic will run on 21CN infrastructure. The Government Communications Headquarters (GCHQ is a British Intelligence agency responsible for providing Signals intelligence (SIGINT and Information Huawei Technologies Co Ltd ( in Shenzhen, Guangdong, People's Republic of China is the largest networking and telecommunications equipment supplier

Potential issues

Any chain is only as strong as its weakest link, and in the case of 21CN, its weakest link – the access network – is also its most valuable. An access network is that part of a communications network which connects subscribers to their immediate Service provider. Although the architecture of 21CN does simplify the network plant, it does not look to solve the problem which will have the greatest effect on data rate, that is loop length i. e. the length of cable from the exchange to the customer. Unlike the active core network, the access network is a passive network and has no capability for self discovery. Reasonable consumer expectations can be established based upon the length and characteristics of these wires. A more global model would require precise knowledge of wire material (e. g. copper or aluminium), where the wires are routed, and the direction in which traffic flows around the circuit. This information is not held at present, and would need significant documentation to obtain.

By moving the MSANs deeper into the network, i. A multiservice access node (MSAN is a device typically installed in a Telephone exchange (although sometimes in a roadside Serving area interface cabinet which connects e. to street side cabinets, length issues are more likely to be reduced, however, line transmission characteristics are still highly variable since lines may be bridged with materials other than copper (such as aluminium) which have a degrading effect on conductivity and hence signal strength. In addition changes in wire gauge (thickness) are often common and introduce signal reflection due to changes in impedance. Wire gauge is a Measurement of how large a Wire is either in Diameter or cross sectional Area. Signal reflection occurs when a signal is transmitted along a transmission medium such as a Copper cable or an Optical fiber, some of the signal power may be reflected The characteristic impedance or surge impedance of a uniform Transmission line, usually written Z_0 is the ratio of the amplitudes of a single

The current 21CN roll out does not look to drive MSANs deeper into the network, instead it locates them in each exchange. Without detailed information on the critical local routings, it is very difficult to ascertain what capacity remains in the duct network and which connections run through it. This makes planning of future upgrades or fibre additions extremely hard to achieve. Openreach is looking at the possibility of integrating MSANs into the access network, although this will probably not happen because there are only 5600 exchange buildings and over 85 000 Primary Connection Points (the place of possible siting of the MSANs, which would push the costs up unnecessarily. Openreach is a division of United Kingdom Telecommunications operator BT Group, established after BT reached an agreement with Ofcom

In July 2007, Sir Christopher Bland, the chairman of BT said that BT was considering fibre to the kerb and that VDSL2 was a 'likely development going forward' but that no final decisions had yet been taken. VDSL2 (Very High Speed Digital Subscriber Line 2 is an access technology that exploits the existing infrastructure of copper wires that were originally deployed for POTS [4]

In October 2007, Ofcom launched a consultation into Next Generation Access Networks in the UK after pressure from the government. The Office of Communications (Y Swyddfa Gyfathrebiadau or as it is more often known Ofcom is the independent regulator and competition authority for the Communication BT will be attending the meetings due to take place soon, although it is expected that they will not be the sole funder of upgrading the access network because they would have to give equal access to other service providers, so they will probably end up footing some of the bill.

References

  1. ^ Le Maistre, Ray. "Analyst: Marconi in Line for 21CN", Light Reading, 27 April 2005. Events 1124 - David I becomes King of Scotland. 1296 - Battle of Dunbar: The Scots are defeated Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. Retrieved on 2006-11-28. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. For the town in Argentina, see 28 de Noviembre. Events  
  2. ^ a b "BT's 21CN has 100 users", The Register, 2006-11-28. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. For the town in Argentina, see 28 de Noviembre. Events Retrieved on 2007-12-04. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. "December 4th" redirects here For the song by Jay-Z, see December 4th (song.  
  3. ^ "Entanet selected for first 21CN broadband trial", thinkbroadband, 2007-09-14. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 81 - Domitian becomes Emperor of the Roman Empire upon the death of his brother Titus. Retrieved on 2007-12-04. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. "December 4th" redirects here For the song by Jay-Z, see December 4th (song.  
  4. ^ Meyer, David. "Outgoing BT chief hints at fibre rollout", ZDNet, 2007-07-19. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 711 - Muslim forces under Tariq ibn Ziyad defeat the Visigoths led by their king Roderic. Retrieved on 2007-08-08. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1220 - Sweden is defeated by Estonian tribes in the Battle of Lihula.  

External links

© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
 Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic