Interconnecting SANs over metro DWDM networks


Storage Area Networks

Alcatel outlines the increasing importance to businesses of data protection through interconnecting storage systems via DWDM metro area networks.

By Laurent Moureu and Pascal Müller, SAN Business Development, Alcatel Terrestial Networks activities

Data is the most important asset for corporations today and, each year, every corporation creates more and more valuable data that has to be managed, stored, and easily restored, anytime, anywhere. Storage Area Network (SAN) technology has therefore emerged to provide real-time transaction and database access over telecom networks.

Consider the following observations from Disaster Recovery Journal:

  • The average company's computer system is down nine times per year for an average of fours hours per event.
  • Downtime costs range from USD15,000 to USD6.5m per hour.
  • Computer downtime costs US businesses USD4bn per year.
  • After a definitive loss of their data, 43% of US businesses never re-open and another 29% close within two years.

To reduce the risk of these occurrences, companies have looked for fast, carrier-grade and transparent ways to interconnect their storage systems, optimising resources and reducing operation costs.

The answer is now available in the metropolitan networking arena, using DWDM networks. DWDM offers fully optical, multi-service, transparent and carrier-grade capabilities, and therefore more than meets storage networking needs (e.g. streaming video, Gigabit Ethernet, SDH/SONET).

Both core and access metro DWDM markets are growing. However, the access segment is thought to have the greatest potential. Analysts such as RHK are forecasting that, by 2005, up to 60% of the metro DWDM market will be in access.

If the focus is now on storage, it is important to understand that DWDM technology is protocol independent, and that such solutions for metro networks lead to the development of multi-service networks.

Storage market potential
In the metro access market, Storage Area Network services will be among the key services offered.

With up to 210,000 links in 2003 and a potential market value of USD25bn in 2005 (IDC, Global SAN Market), the growth of this segment will be one of the key drivers of metro DWDM. This huge market potential includes both IT storage infrastructure, Fibre Channel switches, and DWDM equipment.

To assess the SAN interconnection market opportunity, it is necessary to analyse both the metro and SAN markets.

A telco business or an IT business
Historically, local point-to-point storage has been an IT business (mainly ESCON driven). However, the market is restructuring itself as storage is now going over telecom networks (mainly Fibre Channel driven) and service providers want to offer to their corporate clients storage services or DWDM transmission (one or several "lambda" over a protected fibre pair with a high SLA).

Data is mission critical and players like banks, stocks markets, R&D centres and insurance companies often invest in order to acquire in-house DWDM knowledge and in-source DWDM systems, aside from their storage systems. In this way, they can ensure that no one can access their data in the telecom network.

In this case, scaling the network becomes a real issue and the expertise required to operate and maintain such a network is not a core competence. In either case outsourcing will play a part.

IT and telecoms vendors therefore need to learn to work together. One of the major concerns here is the way the IT industry has historically viewed storage solutions from a data perspective, whereas the telecoms industry has viewed it from a transport perspective. From a physical point of view, transport doesn't have any impact on data or data security, and most of the service providers ensure a network availability of almost 100%.

Market evolution
Storage architecture is currently conducted mainly via point-to-point connections, but this configuration will change in the near future.

On the one hand, users no longer buy dedicated services - they need complex all-in-one corporate communications solutions.

On the other hand, the constellation is changing: an increasing number of customer locations are being combined. So, instead of point-to-point, the result is Universal Data Access over metro networks.

The fundamental approach is to offer leased data services or telecom services from one multi-service network node, as required (see Figure 1).

A multi-vendor environment
The storage area network market has a multi-vendor structure. In this multi-vendor environment, players must deliver end-to-end certified solutions. For example, storage vendors (e.g. EMC, HP-Compaq, IBM, SUN) currently sell their SAN solutions with integrated Fibre Channel switches from a host of other vendors (e.g. Brocade, Mc Data), with or without OEM. Industry certification is the key to success within this market structure.

DWDM vendors will also have to adapt to this model due to co-selling and OEM agreements. As transport will usually be carried out by a service provider, DWDM vendors only have to provide certificates that prove their systems work properly with the solutions from storage vendors. This enables service providers to further guarantee interoperability to their clients.

Market strategies
What is the most effective way to position a metro solution in the market?

Alcatel believes that the main factor lies not in isolated solutions but in partnerships, i.e. a solution only makes sense when it is supported by, and tailored to, the IT partners, the network manufacturers and the carrier (see Figure 3).

Storage Area Network interconnection over DWDM is a new and challenging business. The technology is mature but the market has yet to learn how to structure itself in order to grow.

Enterprises currently need to find storage solutions, but they are concerned about letting service providers transport their mission-critical data. So, it is the role of SAN IT vendors, together with telecom DWDM vendors and service providers, to understand the needs and concerns of their clients, in order to propose the right solutions and business cases. Since "one solution fits all" is out of the question, alliances on a local basis will be key for this market to develop. Vendors and service providers that recognise this early will gain the most from this thriving market.

Scenario 1: Mission-critical data and business continuance
Data centre access anytime: For enterprises, mission-critical data has to be secure. In Korea, for example, all banks are forced by law to have a disaster recovery centre. In Europe, several countries are now giving the legal responsibility for data to members of the Boards of Directors of companies and not to the IT managers, which must have an impact on investment strategy. In other cases, insurance companies only accept clients that can prove they have such a structure in place.

Scenario 2: Cost savings and decreased time-to-market

  • Optimised bandwidth utilisation: Corporate buildings with limited fibre connectivity may access additional services with no expansion requirements.
  • Faster deployment of new requirements: In the case of immediate need for new services (e.g. a new Fibre Channel link or even a digital video link for conference transmission), adding a wavelength (l) is faster and more flexible than expanding the physical fibre capacity.

This will often be the case for large corporations that have increasing needs for new data services (storage, video, Gigabit Ethernet) on top of voice services. In an existing network, they will often have difficulties finding a new dark fibre, so DWDM is the best way to evolve cost efficiently and quickly towards a multi-service network. RHK (March 2002) believes that in 2005 as much as 50% of metro DWDM spending in North America will be for storage applications support. Europe tends to evolve at the same pace, so it will probably be the same case here too.

Scenario 3: Optimising networks to protect investments

  • Scalable solution: The DWDM entry-level configuration is scalable according to service growth and can be expanded into a logical 32l protected node (as in the case of the Alcatel 1696 Metro Span). The composition of traffic (data, telecom or l services) does not matter in this case. Expansion increases according to the requirements of the user (pay as you grow).
  • Network optimisation: A lot of bandwidth is gained through optimal use of a single fibre (with 32l = 80Gbit/s per fibre in the metro range, with 2.5Gbit/s transponders; up to 320Gbit/s with 10Gbit/s transponders) rather than the common practice of, for example, using one dark fibre for one Gigabit Ethernet. In addition, up to four signals may be combined into one l (2.5Gbit/s) via SDH mapping (ETSI standard).
  • Future-proof solution: The scalability of the solution is not limited to one single box. The operator can very quickly and efficiently meet increasing bandwidth needs, as well as the increasing variety of services.

Scenario 4: Global multi-service network implementation - universal data access

  • Universal data access becomes reality: While globe-spanning storage networks are already being built, they are noticeably changing from static to dynamic networks. Data is no longer stored on one server but in storage pools, which are interconnected and combined in a global storage area network.
  • Transparent transport of different protocols: Fibre Channel, ESCON, digital video, Gigabit Ethernet, SDH.
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