Optical systems are the only way to deliver the bandwidth necessary for Europe's escalating level - and variety - of broadband traffic.
By Antony Savvas
The delivery of broadband services to companies and consumers is undoubtedly creating an increase in data traffic, and those carriers still expanding their networks will increasingly need to rely on optical solutions. But how is the European market coping?
Tor Hammarström, solutions manager at Ericsson Optical Networks, says of the situation: "Most major operators in Europe are currently looking at the future of interactive multimedia services and the bandwidth requirements these services impose on their networks.
"And there can be no doubt that optical systems are the only feasible solution to deliver high bandwidth over the distances required to offer these services - both now and in the future.
"There are important advances in increasing internet protocol capability of optical networks, such as the vision of an all-IP-over-glass network, but currently the most important issue is to stimulate market demand.
"The key to the future of optical networking is to make the best use of the bandwidth available in the optical backbone and metropolitan networks. To achieve this it is essential to bridge the 'last mile' gap and bring high-speed access to businesses and residential end-users."
Hammarström says European providers already have a good start to build on as a result of many fibre networks reaching from the core network to offices and homes, and more buildings are now being built with fibre infrastructure in mind (see Fig.1).
The optical activity in the metropolitan area network is also borne out by research from Alcatel. "It is the metropolitan area network that most European operators are focusing on. Today, this network is responsible for the major bottleneck, as the core network has already undergone major investment and changes," says a spokesman.
"The MAN is unique, as sufficient bandwidth is either unavailable or only obtainable through expensive leased lines. Because development of a MAN entails high construction costs with installations in built-up and densely populated areas, network overlay in the MAN is much more expensive than in the core."
MAN development also requires the need to provide multiple service interfaces, with diverse applications in a MAN including storage area networking, optical virtual private networking, streaming video, and voice over IP. This needs a mixture of protocols in the MAN, with SONET, SDH and ATM taking the key roles, and Gigabit Ethernet gaining momentum.
Unfortunately, the technology applied in the core to reduce costs through either efficient aggregation to higher speeds or by eliminating regeneration with optical amplifiers and dense wave division multiplexing (DWDM) typically isn't applicable in the MAN. Distances are shorter and there is the problem of different protocols.
Many operators also implement expensive management systems to support levels of reliability that are incompatible with existing long-haul technology.
Alcatel adds: "Because of the application and service mix in the MAN, previous attempts to solve the problems tried to accommodate every kind of protocol using a single box solution. Using exotic aggregation techniques not compatible with management systems, these boxes caused the network to perform woefully."
Analyst company Yankee Group says the network builders have to change their emphasis from simple build to management. Yankee analyst Chris Lewis says providers have been too quick to emphasise the technology behind their networks, instead of homing in on real-user demand to create the necessary revenue streams. Ownership of the network isn't that important now either, with virtual operators ready to step in where the incumbents do not deliver.
As far as British Telecom (BT) is concerned, it also predicts a greater emphasis on the management of new optical builds, with operations support systems (OSS) becoming more sophisticated to cope with broadband demand.
Rob Hooker, product manager at BT Ignite Carrier Services, says optical provisioning is still largely manual at the moment, and that the infrastructure needs to have better OSS solutions in place.
BT Ignite thinks it's stepping in the right direction with the launch of its highly advanced and flexible DWDM network in The Netherlands, which links more than 20 dutch cities.
This network delivers high-speed Internet, voice, and multimedia communications for BT Ignite customers at speeds of between 2Gbit/s and 10Gbit/s, using optical circuits that can be accessed from any node on the network. Customers include GigaPort, a Dutch government and business initiative that aims to give The Netherlands a lead in the development and use of Internet technologies.
As far as the last mile is concerned, Cisco is focusing on a solution which it calls "Ethernet First Mile" (see Fig.2). Bernard Lamy, Cisco European product manager, says: "If you want broadband TV, high-speed Internet, and video-on-demand, you don't need to run a cable to every office and home (see Fig. 3).
"You can run optical cable to a building, put a switch in the basement, and provide Ethernet socket capability in each office or home via existing copper, which isn't as expensive for service providers."
Lamy says this solution is a good opportunity for start-ups to steal ahead of incumbents who are still plugging away at providing the infrastructure in exchanges to deliver services like DSL.
One of Cisco's customers using EFM is Acantho, which has optical cable going into its customers' buildings throughout the Milan metro area. Acantho is delivering Gigabit Ethernet, with the access achieved using the IEEE 802.3ah standard. Broadband TV is a major application being developed by Acantho for its customers, says Lamy.
Cisco's "mix and match" approach is supported by companies like Riverstone Networks, which also sees Ethernet combined with new technologies as a solution.
Richard Benwell, Riverstone European marketing director, says: "The key to success in the broadband metro optical space lies in the ability to deliver services to individuals over a shared optical infrastructure.
"The reason some operators find the metro network too expensive is that they are proposing long-haul solutions in a short-haul environment. Delivering individual fibre strands to single customers is far too expensive both for the operator to provision and for the customer to buy."
Metro router companies like Riverstone are using solutions like Gigabit Ethernet, Multi-Protocol Label Switching (MPLS), and Resilient Packet Ring (RPR) to help operators deliver services like broadband TV over a shared fibre optical network, which reduces the cost of deployment and allows a lower cost of entry for the customer.
Companies which use Riverstone's Layer 2 routers to provide broadband services like broadband TV and video conferencing include Neosnetworks in the UK, Utfors in Scandinavia, Telenet in Belgium, Completel in France, and Storm across Western Europe.
Neosnetworks marketing director Neil Fairbrother says: "Ethernet on its own will not provide the quality of service necessary for voice. But when combined with MPLS, and when switched at Layer 2, and not routed at Layer 3 (Internet), network performance is at least as good as SDH or SONET, at a fraction of the price."
Fairbrother confirms Ethernet's long-distance capabilities by quoting some latency figures for Neosnetworks links. He says there is latency of 1.75ms from London to Manchester - well below the 250ms the human ear will notice.
The expansion of optical networks to deliver broadband services will come to rely on a variety of solutions, which does away with the simple requirement of just making available capacity as seen at the core.
Now, more than ever, the careful management of capacity in partnership between operators, service providers, and customers is key to broadband evolution.
- Minimal initial investment
- Compatibility with current infrastructure
- Reduced operational costs
- Compatibility with the management network
- Creation of new profitable services
- Metro Access solutions extend MAN transmission, supporting SONET and/or SDH rings at 2.5 or 10Gbit/s.
- Metro Core systems provide optical transmission between central offices in a metro structure, and they interconnect this metro infrastructure to POPs for access to regional and long-haul transport facilities. Supporting 2.5Gbit/s and/or 10Gbit/s SONET and/or SDH compliant rings, metro core systems offer between four and 66 wavelengths per chassis.
- Metro edge systems integrate multi-service capabilities with DWDM, reducing the network elements needed to aggregate and transport access traffic within the metro structure.
- The metro Ethernet router market includes platforms for metro POP-to-POP interconnectivity and aggregation at the POP or data centre. Routers in this class typically scale from 32-256Gbit/s (up to 128Gbit/s full duplex).
- WAN Dense Wave Division Multiplexing systems are the long-haul and ultra-long-haul transmission systems used to increase the traffic capacity of fibre optics by multiplexing multiple service channels over discrete wavelengths on each fibre. Used in conjunction with SONET transport, routers, or switches, these systems multiplex from 320Gbit/s to 3.2Tbit/s onto a fibre pair or strand.
- Optical switches provide the means to manage, control, and switch wavelengths at the edge and core in an optical network. Switching wavelengths from one route to another, optical switches respond dynamically to fluctuating demands in a wavelength-switched network.
- Passive Optical Network Systems provide carriers a means to split the bandwidth from a single fibre access line among a cluster of buildings without active electronics, enabling carriers to deliver high-capacity bandwidth over dark fibre without the cost associated with making fibre "active" to each commercial or residential building.
- Free Space Optics (FSO) systems are line-of-sight transceivers using unlicensed spectrum to provide "last mile" transport to extend the MAN access ring or as point-to-point systems in campus applications.
Extra traffic from new mobile data services and future fast ones using broadband 3G means that mobile carriers have to power up their networks using optical technology.
Vodafone, the largest mobile carrier in Europe, is lighting up a new, wholly owned optical network in the UK, using optical switches from Sycamore Networks and dark fibre supplied by Global Crossing to cope with the rapid data expansion.
Mike Pinches, networks managing director at Vodafone UK, says: "Phase 1 is delivering services across the main London sites and the infrastructure is capable of rapid expansion to support up to five terabits of information."
The UK network will be completed over several years, and the flexible mesh infrastructure will eventually be able to support up to 62.5 Terabit/s of capacity.
Virtue Broadcasting has signed a deal with Interoute to use its i-21 fibre-optic network to deliver television quality video streaming over the Internet to 168,000 major businesses across Europe (see network diagram, right).
Interoute has access nodes and hosting centres in 45 major cities in nine countries across its 14,500 kilometres of fibre, and owns everything down to the connection ducts. Interoute uses Corning G.655 LEAF optical fibre and DWDM is being deployed across the network.
Optical broadband through the air
Where companies do not want to commission new digging to link up different parts of their business in densely populated areas, they can use Free Space Optics (FSO) to do it. FSO involves laser beams being "fired" from building to building carrying the data.
LaserBit Communications, a British-American-Hungarian company, is one player in this market, and claims it has patented technology that can carry laser beams up to 5km between points. Bad weather conditions like fog can impinge on the availability of such solutions, but LaserBit says it can reach 99.9% availability levels or higher at 5km. The company says this reliability beats microwaves and spread-spectrum radio as a transport mechanism. A Formula One racing team has already signed up for the system to enable a 100MBit/s link, and a train operator in south-east England is using the system to link a new customer service centre to another building separated by an electrified railway line.
Networks and Telecoms
Antony Savvas is a freelance networks and telecoms journalist and can be reached at firstname.lastname@example.org