October 1998

BY TONY RYBCZYNSKI

While there are enterprises that can afford dedicated broadband facilities between their sites, broadband networks are mostly the domain of carriers. And yet enterprises of all kinds - not just the high-end enterprises - look to broadband technologies to bridge the growing gap between current network cabilities and emerging business requirements. Thus, many enterprises are attracted to the idea of leveraging carrier capabilities. Enterprises seek to leverage carrier capabilities directly, by taking advantage of carrier service offerings, and indirectly, by emulating, to the extent practicable, the broadband networking trends in the carrier space.

CARRIER NETWORKS
It is the carriers who have the necessary economies of scale to build broadband access and backbone networks. Let's review what's happening in carrier backbone networks, in the areas of switching and transport, and in the access networks, where several last-mile technologies are emerging.

Switching
Service providers around the world are building backbone networks of IP multi-gigabit routers and ATM core switches running on a common optical transport infrastructure. In 1999, IP terabit routing switches supporting multiple classes of service and high-capacity optical interfaces will form the backbone of the Internet, a major step towards making the Internet more scalable, more reliable, and more application friendly. ATM core switches will support multiple service environments such as private lines and switched telephony. ATM is the only packet infrastructure technology that can support circuit emulation and "pin drop" quality voice services, though alternate IP voice services (with different price/performance) are also being introduced. Most frame relay traffic today runs over ATM. Together, frame relay and ATM services describe a service continuum, with frame relay to ATM interworking being widely available for data, and soon to become widely available for voice. In the longer term, frame relay will be one way of accessing ATM services (see my August Inside Networking column "Frame Relay Finds Its Voice"). While IP running directly on the optical layer is the industry direction, the reality today is that most IP/Internet traffic actually runs over ATM backbones, because this approach provides superior price/performance and meets the need for Layer 2 traffic management.

Transport
The optical transport infrastructure is built on fiber transmission because fiber systems are the technology of choice to transport all sorts of traffic (telephony, private lines, data services, Internet, broadcast TV) in carrier networks. Most of these systems today deploy SONET, running at speeds up to OC192, which corresponds to 10 Gbit/s. In addition, many systems, in heavy cross-sections, use Dense Wave Division Multiplexing (DWDM). SONET is a set of standards providing bandwidth management (of T1 pipes, for example) and ultra-high reliability and operational capabilities on fiber systems. DWDM is used to increase the capacity of fiber systems, by running parallel broadband payloads (for example, SONET streams, IP, or ATM) on multiple frequencies or wavelengths on a single fiber. DWDM increases the capacity of the installed fiber by the number of wavelengths used. Today, SONET with integrated DWDM is the workhorse of carrier networks running at speeds up to 160 Gbit/s per fiber. One major reason that SONET is so popular is that it is a standard. SONET products have been commercially deployed for almost a decade, supporting fault sectionalization/problem isolation in multivendor networks. SONET supports standard mappings of a wide variety of payloads, including voice, ATM, and IP - to mention only a few. This permits true multivendor interconnection of a variety of equipment. By contrast, DWDM is a relatively new technology for which standards are still being developed. In any case, the future will be a hybrid world of SONET running on DWDM, and standalone DWDM systems. The choice of technology will be largely driven by price/performance. For example, DWDM directly on fiber may become an economically attractive solution for broadband payloads in environments in which fibers can be dedicated to these applications (perhaps in certain metropolitan environments).

Access
Carriers are deploying various last mile technologies to extend the broadband networking infrastructure to customer premises. These technologies take many forms: fiber to larger business locations; a plethora of wireless technologies (including point-point and multipoint microwave and satellite); cable modems; powerline systems; and various forms of broadband digital subscriber line (xDSL) technologies. xDSL shows promise as a way to extend broadband networking to smaller business sites and to the residential market at large. While there are many xDSL variations, the one labeled consumer DSL (or multimegabit modems by some vendors) will likely have the largest penetration because of its compatibility with existing residential wiring. This form of DSL will deliver 1 to 2 Mbit/s of data bandwidth and voice. In business environments, the first choice is fiber. But, currently, few businesses have fiber - less than 0.1 percent, in fact. Moreover, broadband access for businesses may exhibit lots of diversity. Factors that may contribute to this diversity include the characteristics of any given business location, bandwidth and connectivity requirements, and the degree of carrier competition.

ENTERPRISE NETWORKS
As demands on current networks escalate, businesses are moving towards more powerful, next-generation networks. The idea is to build networks that can take advantage of broadband technologies, and thereby cope with such challenges as increasing network complexity, burgeoning IP traffic and application growth, the move to client/server and Web technology, increasingly mobile enterprise users, and ever-expanding costs of ownership and management.

Some enterprises are in a position to deploy their own broadband infrastructures. For example, in campus environments, broadband networks based on 10, 100, and (soon) 1000 Megabit ethernet switching (and, to a lesser extent, on ATM technologies) are already well established. Other enterprises, while they recognize the importance of broadband technologies, find the costs prohibitive, at least for now. In the meantime, these enterprises may be able to leverage the broadband investments made by the carriers. That is, enterprises can simply subscribe to carrier broadband services.

Services
There are fundamentally three wide area broadband connectivity service categories offered by carriers. These services can be accessed through a broad range of narrowband to broadband dedicated and switched access interfaces using wireline or wireless technologies.

There are, in addition to the broad range of service provider transport offerings, a range of VPN service offerings designed to provide the enterprise with access to the carrier's broadband infrastructures and the improved price/performance that they offer. In addition, through VPN services, enterprise users can outsource the complexity of managing private networks, allowing the enterprise to focus on its own business.

Optical Transport Services: Many corporations already use SONET rings leased from their favorite service provider on a metropolitan basis. In this case, a multiplexor is deployed to consolidate the range of traffic types. Availability of SONET gear with direct ethernet interfaces is providing another option that allows more cost effective campus LAN extensions across a MAN. In the future, DWDM for broadband payloads such as IP and ATM trunking will also be increasingly available running over dedicated fiber.

Public IP Services: Public Internet services are bursting at the seams, with consumers and businesses alike using the Internet for remote access, Web-based service, and IP connectivity, and with an explosion in new applications ranging from e-commerce to distributed interactive gaming to pointcast. In the case of enterprise users, firewalls, encryption, and tunneling are all elements of the solution addressing the need for security in an Internet environment. Service providers are starting to explore ways of adding multiple classes of service to their Internet offerings. This sets the stage for IP telephony as a toll bypass service and for a plethora of new multimedia applications.

Virtual Circuit Services: Frame relay services, offered at speeds up to T3, are mainstream as a private line alternative. Frame relay switched virtual circuits and COS are being introduced by some carriers, driven partially by voice applications. ATM switched and permanent virtual circuit services are increasingly becoming available, these being offered at T1, T3, OC3, and higher speeds. Interworking for IP traffic is also supported between these environments.

VPN Services: A VPN is a managed service offered by a service provider, in which secure connectivity, management, and addressing, equivalent to that available on a private network, is provided on a shared public network infrastructure. (For more information, see the sidebar entitled "VPN Service Types.")

Internal Initiatives
Although most enterprises can't afford their own dedicated broadband networks, they can still take internal initiatives to leverage these carrier developments to their strategic advantage. Here are a few key strategic moves that enterprise IT managers can take:
Standardize On IP For Remote Access And Extranet Applications: While enterprise users are moving slowly towards an IP world in their intranet environments, they should only use IP for new remote access and extranet applications so that they can optimally use carrier broadband access offerings. This is the basis of the big push by carriers. Coincidentally, it fits industry trends of targeting IP for all new applications.

Organize To Be Able To Leverage Voice/Data Convergence Technologies: Packet voice has emerged as an enabling technology to allow cost-effective integration of voice and data, initially in the WAN and ultimately to the desktop. In a broadband environment, moving voice onto data-driven networks is technically and economically viable. In narrow and wideband environments, moving voice onto data networks can enable the transition towards next generation networking architectures. The result is voice/data integration, lower costs per minute for voice traffic, and improved performance for data. The longer term opportunity is for new ways of doing business and reaching customers.

Consolidate All Inter-Site Traffic: Users are turning to broadband switching technologies to improve networking price/performance, to maximize application performance, and to be more responsive to the rapidly changing needs of end users. To take full advantage of these technologies, enterprise users need to take whatever traffic is generated inside the building, and to carry it effectively between sites over the most appropriate wide area service.

The good news is that the market has matured with multiple vendors offering enterprise network switch products that perform this consolidation function. Industry leading corporations in industries such as finance, healthcare, and transportation have embraced the concept of the enterprise network switch as their next generation platform, demonstrating the value of integrated enterprise networks: simplification, increased reliability, application agility, and cost effectiveness. The enterprise network switch is specifically designed for multimedia network consolidation of bit, byte, cell, frame, and packet traffic, and integrates IP switching to provide low latency, high performance, IP-optimized networking.

The industry is "crossing the chasm" from the realm of the early adoptor to the realm of the early majority. Enterprise users would be well advised to assess how Enterprise Network Switches can help them leverage broadband networking for their business advantage.

If you already have an integrated network running on T1 muxes, think twice. T1 muxes represent a dead-end technology, and they don't allow you to leverage carrier broadband access and core infrastructures. With Y2K around the corner, it doesn't make much sense to continue to invest in these technologies.

CONCLUSION
Broadband networking is a key element of next-generation enterprise networks. Broadband networking lowers the cost per bit, decreases latency, enables the network for new application, and can provide seamless performance from remote user to head office. By leveraging the services of carriers who are already employing broadband technologies, as well as making forward-looking changes to their own networks, enterprises of all types and sizes can gain from broadband networking in a manner that is both affordable and progressive.

Tony Rybczynski is director of strategic marketing and technologies for Nortel's Enterprise Data Networks business unit. Enterprise Data Networks focuses on offering alternatives to increasingly complex data network infrastructures, through direct and indirect sales channels. For more information, visit the company's Web site at www.nortel.com. To contact the author, send e-mail to [email protected].

There are four key VPN service types that allow users to leverage the carrier's broadband infrastructure. Any one or a combination of these VPNs deliver network and application level security, customer service, and network management capabilities, including monitoring, configuration management and billing, and embedded quality of service (QoS). They include: Remote Access; Intranet VPNs; Enterprise VPNs; and Extranet VPNs.