Cogent Fast Ethernet Adapters & Repeaters An Outline of Cogent's Strategic Plan For Fast Ethernet Products: A Complete Solution For All 100BASE-T Cabling Standards Paul Cunningham Director of Product Marketing Today's LAN users expect their tasks to be performed as quickly as possible. They do not understand network delays, especially during peak traffic. In fact, for most users, the reasons for bottlenecks and slowdowns only seem to add to the frustration. Consistent high performance network computing is what they desire. This problem of delays is further compounded by the steady increase of PCs being connected to LANs. This is coupled with rapid changes in PC technology and software innovation, and rapidly decreasing costs. In addition, there has been increased use of resource-intensive applications, such as multimedia and advanced software tools. Together, these driving factors are pushing the limits of existing 10 Mbps (megabits per second) LANs. The 10 Mbps pipe is rapidly becoming too small to transfer large amounts of data efficiently. The Advantages of Fast Ethernet The need to provide a high performance solution that meets the needs of LAN users has spawned a growing market of sophisticated products and new technologies. With the demand for higher throughput, a number of technologies have emerged as alternatives to 10BASE-T Ethernet. These cutting-edge technologies offer increased bandwidth using high speed, 100 Mbps connections. Of these, Fast Ethernet is quickly establishing itself as the preferred standard for 100 Mbps networking. Fast Ethernet or 100BASE-T has gained this reputation because it operates like the 10 Mbps conventional Ethernet, only 10 times faster. By building on conventional Ethernet, Fast Ethernet offers superior compatibility with todayFs networks at affordable prices. This combination of speed, compatibility and price make Fast Ethernet the first choice for giving networks the power they need - both for today and tomorrow. Specifically, Fast Ethernet offers: Standard, proven technology Fast Ethernet (100BASE-T) is a direct extension of conventional Ethernet, only 10 times faster. Due to this compatibility, Fast Ethernet high speed connections can be seamlessly introduced into existing 10BASE-T Ethernet environments. Industry-wide support 100BASE-T Fast Ethernet is widely supported by many major technology companies as an important alternative to 10BASE-T Ethernet. Price/performance Because Fast Ethernet is highly adaptable and enjoys wide support, the price/performance of Fast Ethernet is expected to stay well ahead of the competition. Strategic migration Fast Ethernet offers a reliable alternative to 10BASE-T that can be implemented strategically in a gradual migration. Most often, the migration to Fast Ethernet is cost effective because it makes the most use of the existing infrastructure. Managers can rely on the existing network software, familiar net work analysis tools, equipment and procedures in 100BASE-T environments, with minimal retraining. Fast Ethernet LANs can be managed with existing SNMP management application software and Ethernet management information bases. Consistent evolution As the evolution to high speed, high performance networking advances, 10BASE-T Ethernet will soon be considered old technology. By adopting Fast Ethernet along a gradual migration path, you can ensure that the network is maintained using todayFs technology. Security of investment Migrating to Fast Ethernet establishes a secure investment in the future performance of the network. The wide range of compatible Fast Ethernet products will enable you to make significant improvements to the network well into the future. Interoperability with other environments The acceptance of Fast Ethernet in existing environments will establish a strong market place for products. In turn, this will create enhanced interoperability with other technologies, such as Token Ring, ATM, FDDI, and so on. Fast Ethernet Technology 100BASE-T Fast Ethernet applies to the IEEE 802.3u standard (an extension of the existing Ethernet IEEE 802.3 standard). Fast Ethernet uses the existing 802 MAC layer, connected through an MII layer to one of three PHY layers. The MII specification is similar to the 10 Mbps Ethernet AUI. Essentially, the 100BASE-T Fast Ethernet standard performs like traditional 10BASE-T Ethernet, only 10 times faster. All of the remaining functionality is unchanged. Packet format, packet length, error control, and management information are identical to 10BASE-T. 100BASE-T contains a definition of Ethernet protocols and data communication requirements that provide a single interface that is not cable-specific. Fast Ethernet is compatible with all popular media types including twisted pair copper cable and fiber optic cable, which allows for easy migration. The 100BASE-T Fast Ethernet standard also defines a 100BASE-T repeater and a management interface. Within the 100BASE-T Fast Ethernet standard, three compatible media specifications have been defined to meet every cabling need: 100BASE-T4: For most common cabling: A workstation solution 100BASE-TX: For modern cabling needs: A server solution 100BASE-FX: For fiber optic cabling A backbone solution See Media Specifications in this document for additional information. Strategic Migration to Fast Ethernet 100BASE-T Fast Ethernet can be implemented strategically in organizations of any size. Implementation can leverage the value of the existing 10BASE-T equipment, including cabling, network software and MIS expertise. Typically, the migration to Fast Ethernet follows this general path: -Maintain the integrity of the current 10BASE-T networking environment. Keep the current standard 10BASE-T network operating at its current capacity. -Add new 100BASE-T Fast Ethernet capability. Use Fast Ethernet high-speed adapters to all new workstations. Additional Fast Ethernet technology can also be implemented when and where it is needed most. -Configure the network for interoperability between the 10BASE-T and Fast Ethernet products. -Gradually migrate the existing 10BASE-T users to a fully-supported Fast Ethernet environment. 10/100 Mbps Auto-Sensing For the smooth migration from 10 to 100 Mbps, many Fast Ethernet adapters include a dual speed function coupled with an automatic speed sensing feature. Auto-sensing enables a dual function 10/100 Mbps adapter to automatically detect and change to the fastest transmission speed (100 Mbps), with no manual or software intervention. If necessary, a network manager can also use management software to force the segment to operate at either 10 or 100 Mbps. Design Rules for Fast Ethernet 100BASE-T Fast Ethernet is designed to be very similar to 10BASE-T Ethernet. Yet, there are some significant differences between the these two standards, primarily in network configuration. Both 10BASE-T, and 100BASE-T Ethernet permit cable segments up to 100 meters between repeaters and nodes. In contrast, the number of unbridged repeaters permitted with 100BASE-T are fewer than with 10BASE-T because the signals travel faster. For twisted pair cabling, 100BASE-T allows a maximum distance between two network nodes of 205 meters. This distance can be distributed along the path (node to repeater to repeater to node) as desired, provided that no segment is longer than 100 meters. However this distance can easily be extended through the use of either fiber optic cabling, multiport bridges or switches. The basic building block of a 100BASE-T Ethernet networks is the collision domain. A collision domain is a logical network segment which may be connected (bridged) to another collision domain through a bridge or switch. The size of each 100BASE-T collision domain depends on the cable media and class of repeaters used within the domain. This bridged topology makes it possible to integrate 100 Mbps into a 10 Mbps network service. Fast Ethernet repeaters are a device that broadcasts both packets and collisions across a collision domain. The 100BASE-T Ethernet standard defines two classes of repeaters, Class I and Class II, which are distinguished by their internal latencies. Each collision domain can include at most one Class I or two Class II repeaters. Large, well structured networks can be created by designing the Fast Ethernet network to include the appropriate type of repeaters (stackable vs. non-stackable, twisted pair vs. fiber optic uplinks, and Class I vs. Class II), as well as any needed bridges or switches. Cogent's Product Roadmap Cogent is a market leader in high performance Ethernet networking, and in the Fast Ethernet market. Cogent offers a single source for Fast Ethernet products you can use to configure networks that deliver the right solutions, including a wide range of network adapters and repeaters. Fast Ethernet Network Adapters High performance, Fast Ethernet adapters are available for all three media types. Each Fast Ethernet adapter model supports all major PC expansion bus architectures. The 100BASE-T4 and 100BASE-TX Fast Ethernet adapters are available in special combo versions. The combo adapters support 10 Mbps operation with coax (BNC) and RJ-45 connectors. The combo adapters are useful for customers with an installed base of coax (RG-58) Ethernet who wish to upgrade to Fast Ethernet but maintain compatibility with their existing cabling. The models are: EM110 T4 This single port 10/100BASE-T4 adapter supports the PCI, ISA, and EISA bus architectures and provides auto-sensing. The 10/100BASE-T4 Combo model supports 100BASE-T4, 10BASE-T and 10BASE-2. EM110 TX This single port 10/100BASE-TX adapter supports the PCI, ISA, and EISA bus architectures and provides auto-sensing. All 100BASE-TX server adapters support Full Duplex operation at both 20 and 200 Mbps. The 10/100BASE-TX combo model supports 100BASE-TX, 10BASE-T and 10BASE-2. EM100 FX This 100BASE-FX fiber optic adapter provides models with both ST-style (BNC-like) connectors and SC-style (modular) connectors. In Full Duplex mode, distances of up to 2000 meters (2 km) are supported. A 100BASE-TX/T4 super adapter for the PCI Local Bus, will also be available to support 10BASE-T, and both 100BASE-T4 and 100BASE-TX. This adapter will ensure compatibility in any environment. This adapter will be available by special order only. Quartet 400 Series Adapters For network servers and superservers, Cogent offers two unique solutions in the Quartet 400 series adapters. These adapters support up to four network segments on separate channels - all at full cable bandwidth. The Quartet 400 adapters are designed specifically to take advantage of the PCI Local Bus. The PCI Local Bus with 132 MB (megabytes per second) throughput contains enough bandwidth to support multiple Quartets running in a single server. The models are: EM440 T4 Quartet This four-port 100BASE-T4 adapter is ideal for migration from 10BASE-T to 100BASE-T4 networking and provides auto-sensing. This adapter can run on the same cabling as an existing 10BASE-T network (Category 3 UTP or better). EM400 TX Quartet This four-port 100BASE-TX adapter is ideal for 100BASE-TX servers. The EM400 TX Quartet also supports Full Duplex operation. When used with a Full Duplex Fast Ethernet (FDFE) switch, this adapter enables simultaneous bi-directional communication. Full Duplex mode supports throughput at 200 Mbps on each segment, or up to 800 Mbps cumulative throughput in FDFE mode on each EM400 TX Quartet. Fast Ethernet Repeaters Cogent's product line includes a selection of low-cost stackable workgroup repeaters, as well as managed, stackable high-density repeaters, for enterprise-wide use. S-series Workgroup Repeaters The S-series repeaters enable up to 12 ports of East Ethernet connectivity per repeater. S-series has models that support the 100BASE-TX, 100BASE-T4, and 100BASE-FX media types. The models are: -S-1200TX 12 port 100BASE-TX repeater, Class I. -S-1200T4 12 port 100BASE-T4 repeater, Class I. -S-800FX-ST 8 port 100BASE-FX repeater, FX/TX uplink, Class I, ST connectors -S-800FX-SC 8 port 100BASE-FX repeater, FX/TX uplink, Class I,SC connectors The S-series repeaters can be stacked up to four high using the 50-pin connector on the back of the repeater. The 1200T4 repeater can only be stacked with other T4 repeaters. The 1200TX and 800FX repeaters can be mixed in a single stack. All S-series repeaters can be uplinked to other repeaters and switches. The last port on each repeater is configurable for either a standard cable or a cross-connected UTP cable using an MDI/MDI-X switch. In addition, the last port on the S-800FX can be selected either for an 100BASE-FX fiber connector or the 100BASE-TX connector. SM-series Stackable and Manageable Repeaters SM-series stackable repeaters are designed for maximum flexibility and expandability with 24 ports per repeater. These repeaters can be easily integrated into enterprise-wide networks and provide the basis for Fast Ethernet backbones. SM-series repeaters can support the 100BASE-TX, 100BASE-T4 and 100-BASE-FX cable standards. Each SM-series repeater can also accept an optional uplink module of any Fast Ethernet media type to provide additional interconnectivity. The models are: -SM-2400TX 24 port 100BASE-TX repeater -SM-2400T4 24 port 100BASE-T4 repeater -SM-1600FX-ST 16 port 100BASE-FX repeater, ST connectors -SM-1600FX-SC 16 port 100BASE-FX repeater, SC connectors Five optional uplink modules will be available for the SM-series. These are 100BASE-TX, 100BASE-T4, 100BASE-FX (ST and SC), and MII. The uplink module acts as an extra port that can either increase the number of available ports or add a port of a dissimilar media type. This can be extremely useful in cases such as mixed 100BASE-T4/TX networks or mixed 100BASE-TX/FX networks. The management of the SM-series can be accomplished either via in-band or out-of-band management. Out-of-band management is provided via an RS-232 port. The management module supports standard SNMP, MIB variables. The SM-series repeaters can be stacked together in any combination. This allows mixed networks of 100BASE-T4, 100BASE-TX and 100BASE-FX media types to be easily created. Up to five SM-series repeaters can be stacked to form a single manageable unit. Together, this unit can connect up to 120 Fast Ethernet devices. Media Specifications Three compatible media specifications have been defined in conjunction with the 100BASE-T Fast Ethernet standard to meet virtually every cabling need: -100BASE-T4 -100BASE-TX -100BASE-FX Each of these media specifications is appropriate for different uses, and many network installations will use two or three in combination. These media specifications can be mixed together and interconnected through a repeater, just as 10BASE-2 and 10BASE-5 coaxial Ethernet can interoperate with 10BASE-T, twisted-pair Ethernet. These media specifications permit 100BASE-T Fast Ethernet to be integrated into nearly any 10BASE-T environment using the existing cabling infrastructure. 100BASE-T4 100BASE-T4 is the most flexible media specification in terms of cable requirements. The 100BASE-T4 media specification transmits 100 Mbps data using four pairs of unshielded, twisted pair (UTP) wiring. Three wire pairs are used for transmission, the fourth pair is for collision detection. 100BASE-T4 can use voice grade cable such as Category 3 or 4 (CAT 3 or 4 UTP) cabling or data grade Category 5 (CAT 5 UTP) cabling. Category 5 is a robust, widely installed UTP cable. 100BASE-T4 can easily meet the needs of the installed base of older 10BASE-T networks, many of which are cabled using Category 3 (a common cable in todayFs networks). 100BASE-T4 can also be used when the installed cabling is improperly terminated Category 5 or of an uncertain quality. 100BASE-TX The 100BASE-TX media specification supports data transmission at 100 Mbps using two pairs of twisted pair wire. One wire pair is used for transmission, the other is for collision detection and receiving. (It defines the same two pairs as the 10BASE-T specification). 100BASE-TX also supports Full Duplex mode, unlike 100BASE-T4. This specification calls for data grade EIA 568 Category 5 unshielded twisted pair. Many new buildings and network installations being built today are wired with at least two pairs of Category 5 cabling, which can take advantage of 100BASE-TX. Together, the 100BASE-T4 and 100BASE-TX specifications cover all cable types currently in use in 10BASE-T networks. 100BASE-FX The 100BASE-FX is a wiring scheme that can transmit 100 Mbps over two strands (one pair) of fiber optic cable. 100BASE-FX supports extended network distances of up to two kilometers or about ten times the distance for copper cabling. 100BASE-FX can be used between the floors of buildings, where elevators and electrical interference may be a factor. Fiber optic cable can also support extended distance LANs, downlinks and backbone technology. 100BASE-FX supports Full Duplex mode. About Cogent Cogent Data Technologies, Inc. was founded in 1982. The company is headquartered in Friday Harbor, Washington, with sales offices in Bellevue, Washington and Munich, Germany. Cogent designs and manufacturers its products in the USA and markets these products worldwide through its OEMs and distribution customers. For More Information, Contact: Cogent Sales Cogent Corporate Cogent Europe 15375 SE 30th Place, Suite 310 640 Mullis Rosenstrasse 7 Bellevue, WA 98007 U.S.A. Friday Harbor, WA 98250 U.S.A. 80331 Munich Germany Tel (206) 603-0333 Tel (360) 378-2929 Tel [49]89/231138-88 Fax (360) 378-2882 Fax [49]89/231138-11 Fax (206) 603-9223 Toll-free in U.S. 1-800-426-4368 E-mail sales@cogentdata.com 1994 Cogent Data Technologies, Inc. All rights reserved. Printed in U.S.A. Product specifications are subject to change without notice. Cogent is a registered trademark and eMASTER+, Predictive Pipelining, and Quartet are trademarks of Cogent Data Technologies, Inc. All other trademarks are the property of their respective owners.