Ethernet Becomes King Of The Networking World

Calling ethernet a success story is the understatement of the year. Ethernet is about as ubiquitous as you can get. Whatever happened to ARCnet, AppleTalk, Token Ring, MAP, FDDI, and the many other local-area networks (LANs)? Not only has Ethernet replaced them all, but now it's moving into every other area of networking, including metropolitan-area networks (MANs or metros), storage-area networks (SANs), and wide-area networks (WANs). But it doesn't stop there. Ethernet also owns the wireless networking space, big time.

Talk about a dominant technology. When they were inventing Ethernet, Bob Metcalfe and his colleagues didn't realize they were creating the ultimate networking solution (see "What Is This Thing They Call Ethernet?," p. 48). It has changed some over nearly 30 years, but so has the technology, and it's still evolving as you read this article.

Whenever we think of Ethernet, most of us picture the typical enterprise LAN running 100 Mbits/s over CAT5 twisted-pair switched stars. Almost everyone has one now. A few Token Ring LANs still exist, yet even these are slowly giving way to Ethernet's relentless onslaught. But if you haven't been paying close attention, you may not know that Ethernet has worked its way into almost every other niche of networking. Consider these applications:

• MANs: The newer 1-Gbit Ethernet (1GE), fiber-optics version of Ethernet can carry more traffic over longer distances than those typical even for large campus LANs. As a result, some companies have used this new technology to open new businesses in the metro network market. An example is Yipes, who is doing a brisk business of connecting remote LANs via MANs. The newer 10-Gbit Ethernet (10GE) is another candidate for this market. Plus, the Resilient Packet Ring (RPR) effort by IEEE working group 802.17 and vendors like Infineon should ultimately provide the manageability, quality of service (QoS), and security necessary for Ethernet to succeed as a carrier-class metro networking technology.



• WANs: The 1GE and, especially, the 10GE capabilities could find applications in the WAN market. This is now dominated by Sonet, which will no doubt hold on to most of that business. But as we move more to the Internet protocol (IP), Ethernet will become even more attractive. It might eventually take some market share from OC-192 Sonet when carriers begin offering services that let companies connect remote LANs at higher speeds with lower-cost Ethernet switches and without protocol translation.



• Home networking: Only now is this market beginning to take off. Some early home networkers have actually wired their homes with CAT5 twisted pair and installed an inexpensive Ethernet network. Today, many newer homes are routinely wired with CAT5 along with ac power, telephone, cable TV, and security wiring.



• Wireless Ethernet: This Ethernet business segment is growing significantly in the enterprise and the home. Wireless' flexibility is now eminently affordable at all levels. Significant devel- opment continues in this arena, so there's more to come.



• Industrial Ethernet: Many different specialty and proprietary networks for devices, sensors, controllers, and the like have always made up the in-dustrial networking market. But today, most of these specialty networks are giving way to Ethernet due to its wide availability, low cost, and compatibility with adjacent business LANs.

Keepers of the standards for widely used industrial networks are finding they can encapsulate their protocols into TCP/IP and transmit them via standard 100-Mbit/s UTP/CAT5 Ethernet. Some industrial standards now possible with Ethernet are DeviceNet/ControlNet/EtherNet/IP, Profibus-DP/Profinet, Modbus, and Foundation Fieldbus H1/HSE. Security and real-time issues not solved by Ethernet are being handled. But plants and factories are enjoying the high speed, low cost, wide availability, and compatibility with office LANs Ethernet offers.

• SANs: As storage needs increase in all business sectors because of massive e-mail files, more multimedia data, and the need to have faster, easier access to data, SANs are growing in number. SCSI is still the most widely used SAN interface, but the popular Fibre Channel (FC) standard has grown dramatically over the years. FC's 1-Gbit and now 2-Gbit rates make high-speed access possible, but it is expensive.

Ethernet is slowly working its way into this sector. A forthcoming ITEF standard called Internet SCSI (iSCSI) encapsulates the SCSI protocol into IP packets and transmits them via Ethernet. This provides higher speeds than FC and eliminates FC's distance limitations (10 km at 1 Gbit/s). Data access with iSCSI can be to a nearby data center or to storage anywhere worldwide via the Internet. While FC is fighting back with the development of a 10-Gbit/s version and its own FC-over-Internet solution, most expect FC to eventually fade away as 10GE and iSCSI make SANs faster, cheaper, and fully compatible with existing LANs.

Ethernet is a hot market. With over 1 billion ports already in place and the growth continuing, it's no wonder that we keep seeing even more new product activity. With so many new Ethernet products appearing almost daily, it's hard to keep track.

1GE Standards: Back in 1998, the 1GE standard was approved. It offers both copper and fiber media options (Table 1). The copper option has become the "sweet spot" in the market simply because users can implement 1GE on existing CAT5 unshielded twisted pairs (UTP) now used for 100-Mbit/s Ethernet. 1GE employs four twisted pairs to get the 1-Gbit/s rate up to 65 m. This offers a fast, inexpensive, and easy upgrade path to 1 Gbit/s for enterprise LANs. High speed is the draw, but 1GE also permits the LAN to handle more users and lets network-attached storage (NAS) systems be accessed at a reasonable speed.

Semiconductor vendors now provide chips that make it possible to include affordable 1GE ports on PCs. These chip sets implement the 10/100 Ethernet ports common on most PCs today but also include the 1-Gbit/s capability. Soon, 10/100/1000 ports will be standard on most PCs and laptops. Just as 100-Mbit/s Fast Ethernet eventually became the standard when its pricing fell into the $100 per port range, 1GE is expected to become the desktop standard as its cost continues to drop.

An example of a 1GE chip set is Massana's Everest series introduced earlier this year. The MA1110 is a single-port device while the MA1140 and MA1141A are quad-port devices. Made with 0.18-µm CMOS, these chips fully comply with the IEEE-802.3, -802.3u, and -802.3ab standards, letting them handle 10BaseT/100BaseTX/1000BaseT connections.

The Everest series deploys a proprietary oversampling technology called IntelliRate. Incoming parallel 125-MHz signals are sampled at 250 MHz, giving two samples per symbol. This technique supplies a better signal-to-noise ratio that leads to an improved bit error rate (BER). Consequently, Massana's algorithms offer superior performance over a wider range of cable types. This heavy digital architecture in the analog front end scales better than traditional ap-proaches and leads to lower power consumption and cost.

Other suppliers of Ethernet controllers and transceivers include Broadcom, Intel, and National Semiconductor. All have lines of Ethernet MAC, physical layer (PHY), and combo chips to meet just about any design need.

For example, Broadcom's recent products address the power consumption issue. The 0.13-µm CMOS BCM5464S quad-transceiver chip cuts power consumption by nearly 30% with its less than 700 mW per port dissipation. Broadcom's BCM5705M, a single chip 10/
100/1000BaseT controller with integrated transceiver for mobile applications, also minimizes the power consumption problem with a low 900-mW dissipation.

Intel's 82540EP is power-consumption-conscious as well. This integrated MAC and PHY chip for 802.3, 802.3u, and 802.3ab standards is optimized for LAN on motherboard (LOM) designs. It communicates via a standard PCI bus. Also, National Semiconductor's DP83820 is a complete 10/100/1000-Mbit/s PCI Ethernet interface controller that covers all the bases in this competitive market.

Another nifty Ethernet product is LSI Logic's StreamPack L64524 managed Ethernet switch for vendors making layer 2 switches. It integrates 24 10/100 ports, two 10/100/1000 ports, and a switch fabric along with a 143-MHz ARM9 embedded processor. The internal MAC address table has a capacity of over 16,000 entries. The two 1GE ports provide links to the LAN backbone or a local server farm. Priority queuing in the chip lets time-sensitive data access the network with minimal delay. While the new chip greatly improves the performance of Ethernet switches, it can also reduce time-to-market when used with the royalty-free companion StreamPack Managed Switch Software (SMSS).

Even though the UTP version of 1GE is hot right now, the 1GE fiber option also is getting some attention. For a new LAN, fiber is obviously the better choice, not only because of the security impact but also due to its greater range and ability to scale to higher speeds in the future. Though fiber has traditionally always been more expensive, that's no longer the case.

According to Herb Gongdon, global fiber product manager at AMP Netconnect, "All of the arguments against installing a fiber in the desk network have been systematically removed over the past five years. Today, you can take advantage of the centralized network design and new fiber technologies to install an all-fiber network at the same cost as a copper network."

Over the years, fiber and connectors have become cheaper and much better. Competition in the optics with the new vertical-cavity surface-emitting lasers (VCSELs) has reduced the cost of transceivers. Fiber has never been a better option.

A really dynamite example is the Narad Broadband Access Network (NBAN). This system by Narad Networks uses 1GE on the fiber in cable TV networks to achieve 100-Mbit/s and 1-Gbit/s connections to small- and medium-size businesses and consumers. Multiple system operators (MSOs), the cable TV companies, can leverage their existing hybrid fiber cable (HFC) networks into even faster data services.

Many cable operators, such as Time Warner's Road Runner, already offer fast broadband connections to consumers. They do this by employing some of the 6-MHz bands in the cable TV part of the cable spectrum from dc to 860 MHz. This takes away spectrum from TV to provide data services. Furthermore, the 6-MHz channels and the bus architecture limit the speeds to several hundred thousand bits per second. Speeds of several megabits per second are possible, yet not typical.

The Narad system uses the cable spectrum above 860 MHz to provide even faster data transmission. Figure 1 shows the cable spectrum. Data is transmitted via the optical fiber at 1 Gbit/s, while taps of coax to the fiber carry 100-Mbit/s data to and from homes and businesses. A switched Ethernet architecture is implemented with a 16QAM modulation scheme.

Narad's Service Delivery Platform (NSDP) is the software that helps to create, provision, and manage broadband services over an existing cable network. It partitions the 1-GHz bandwidth into segments of 100 Mbits/s as required on each fiber network segment.

With this arrangement, who needs the proposed fiber to the home (FTTH) that so many have been predicting and proposing? What's not to like about a 100-Mbit/s Ethernet broadband connection to the home or office over existing cable systems? Narad makes the complete systems, yet it will sell or license the 2-Gbit/s Ethernet modem chip and the software to others.

10GE Standard: The future is now focused on 10GE, which has been under development for the past several years. The 10GE standard was finally ratified by the IEEE-802.11ae working group on June 13, 2002. Table 2 shows the physical layer options.

Semiconductor and equipment companies trying to get a head start in this arena have already been shipping selected chips, optical transceivers, and equipment. While 10GE parts and equipment will continue to be expensive for the time being, costs will decline as volume increases and competition heats up. Even with the high prices, 10GE will still be cheaper than Sonet, so it will make some inroads into the MAN and WAN markets.

Typical of the companies expediting the 10GE adoption is Network Elements. Its MiniPHY-300 optical transceiver transmits 10 Gbits/s up to 40 km with an externally modulated 1550-mn laser. The module meets small form-factor requirements and dissipates under 7 W. It can be used in Sonet/SDH, 10GE, and other applications.

Network Elements also announced the availability of its multiprotocol processor ASIC. Previously, it was only found embedded in the company's own modules. This processor, known as LiASIC, contains a framer and mapper that runs at 10 Gbits/s and is applicable to 10GE LAN, MAN, and WAN equipment; 10GE packet-over-Sonet (POS); or Sonet/SDH systems (Fig. 2).

The chip performs multiprotocol processing, advanced packet filtering, and Sonet overhead processing. It incorporates an OIF SPI-4 phase 2 interface for transferring system-side packets, an OIF SFI-4/802.3ae XSBI interface for connection to PHY modules, an 802.3ae XGMII interface for connection to PCS/PMD modules, and a 16-bit control interface. Network Elements offers accompanying comprehensive application programming interface (API) software for the LiASIC that runs on the customer's line card control processor.

Another new 10GE entrant is Mysticom's MY3004 transceiver. It's a four-channel, 3.125-Gbit/s serializer/deserializer (SERDES) device for backplane and 10GE applications. The MY3004 is compatible with the IEEE-802.3ae 10GE XAUI specification. It incorporates a digital receiver that reduces the BER by two orders of magnitude in noisy environments.

The device uses adaptive line-conditioning software to automatically adjust signal parameters whenever system configurations change. It connects to optical modules that support the XAUI interface, like XENPAK and XPAK. The system-side connection is done via an XGMII HSTL interface at 1.5 V. Just recently, Mysticom demonstrated the MY3004 in operation on two serially connected FR4 copper backplanes of up to 70 in. long.

As 1GE and 10GE packet services are deployed in the MAN and data centers, network equipment manufacturers are seeking to provide carriers with switching equipment for layers 2, 3, and 4. Manufacturers must offer not only an economic solution for Ethernet bridging, VLAN, MPLS, and IP forwarding, but also traffic-management features that let the service providers fulfill their varied service agreements.

Sandburst Corporation's HiBeam chip set offers one solution to this tough problem. Figure 3 shows a line card using this chip set. The FE-1000 forwarding engine uses proprietary address lookup and classifications algorithms to store forwarding tables and Cisco-compatible access control lists in commodity SRAM. This re-duces system cost by eliminating the need for external content addressable memories (CAMs) or coprocessors. The chip is optimized for VPN packet processing. Sandburst delivers it and the microcode together as an off-the-shelf solution requiring no customer programming.

The QE-1000 queuing engine talks to the switch cards by way of 3.125-Gbit/s 8B/10B encoded serial links. The BME-1600 bandwidth management chip controls the switch-fabric chips.

A patent-pending bandwidth allocation algorithm provides fine-grained bandwidth management that can be adjusted in increments of 1 Mbit/s so service providers can provision systems that guarantee bandwidth on a per-subscriber basis and deliver differentiated QoS.

One last thing. 10GE also is being considered for use as a fast serial I/O bus to replace PCI in forthcoming high-performance server and PC designs. While the leading contender in this space is currently InfiniBand, Intel will no longer support it. Could it be that 10GE is not only faster but also cheaper and better?

With 10GE on its way to another Ethernet success, we can look forward to more of the same. The next speed limit of 100 Gbits/s is a huge bump along the Ethernet roadmap. But we can probably anticipate a 40-Gbit/s Ethernet in the near future that will draw upon the developments in the OC-768 (40 Gbits/s) Sonet chips and systems.