The Open Shortest Path First protocol is another recent standard that helps routers perform least-cost routing of traffic. The router performs an on-the-spot analysis of all possible routes at the time and chooses the best one based on user-defined criteria.NETWORK DESIGN CRITERIA. Although bridges and routers are similar at a high level, they differ greatly in detail. Determining the best technology requires an analysis of specific network usage. tiffany and co earring bridges have less intelligence, this is sometimes an advantage.
And while bridges have no real addressing capability, many networks do not require it. Routers have multiprotocol capabilities, but consequently they require more processing for each packet routed. This in turn takes up more CPU resources and can slow down the network's performance.
Many vendors have taken the worry out of choosing by providing bridging and routing in a single device. These devices, often referred to as "brouters," look at packets, initially try to make a routing choice, but fall back to bridging if incapable of tiffany and co necklace so.
A merging of networking functions is about to occur--by the mid-1990s, bridging, routing, gateway, and circuit switching for voice, data, and image functions will be incorporated into a single device. As LANs are increasingly called upon to span multiple corporate sites, the need for wide-area communications will grow, and these internetworking devices will have to support a number of WAN interfaces, such as X.25, ISDN, Frame Relay, SMDS, and, ultimately, ATM. Many of these interfaces are already being implemented by the leading vendors to meet use demands for LAN and WAN routing.Research Triangle Park, N.C.--IBM officials last week mapped out the company's future plans for LAN products, which include this month's expected release of support for 16 bit/sec token-ring nets on unshielded twisted-pair wiring and, later, a family of FDDI products.
At a briefing for Network World here, IBM executives also discussed other key wholesale tiffany jewlery-area network areas that the vendor is exploring, such as wireless networks, multiprotocol net adapters and combination concentrator/LAN cards as well as new Ethernet products."You'll see a lot more this year in terms of what we're putting on the table," said Stuart Sager, manager of LAN planning and support for IBM's networking subsystems division.First out of the tiffany and co ring gate will be support for 16M bit/sec token-ring networks over unshielded twisted pair, which will be rolled out in two phases, according to IBM.First, Sager said, Big Blue will bring out "filtering products" that will let individual workstations support the higher transmission speeds over IBM's Type 3 unshielded twisted-pair cabling. Although he would not be more specific, analysts predicted that IBM intends to bolster the filtering capability of its existing Token-Ring adapters to support higher speeds.
IBM will also enhance its existing 8230 Controlled Access Unit (CAU)--its intelligent concentrator--with new filtering capabilities, so all devices attached to the CAU will be able to run at 16M bit/sec, according to Sager. A user could move to the 16M bit/sec unshielded twisted-pair token ring by upgrading CAU instead of the existing 4M/16M bit/sec cards within user workstations.
Sager stressed that IBM's unshielded twisted-pair products are being developed solely by IBM. Some analysts had questioned whether IBM's offerings would be jointly developed with SynOptics Communications, Inc., which has worked with IBM on a wholesale tiffany bracelets for a 16M bit/sec unshielded twisted-pair standard.
By the end of June, IBM is expected to provide support for Fiber Distributed Data Interface networks in the form of personal computer-based FDDI adapter cards. The company is also working on FDDI bridging and management capabilities.
Big Blue currently offers FDDI adapters for its RISC System/6000 and its 3172 controller. However, executives last week confirmed that IBM will meet the goals listed in a statement of direction circulated two years ago in which IBM pledged to have additional FDDI products and support by this June.
All four features are available now as a free software upgrade.Bytex also said it will roll out within 90 days Simple Network Management Protocol support on its token-ring modules.Finally, the company said it will support by next year the Open Software Foundation, Inc.'s Distributed Management Environment by migrating its net management applications to Hewlett-Packard Co.'s OpenView net management platform.Charlotte, N.C.--What began as Ten row Chain Heart Set simple addition of a new site to this city's SNA network evolved into a complete net overhaul that led to the development of a sprawling LAN internetwork.
Two years ago, when Charlotte's Communications Information Systems department was handed the task of tying the city's new fire station into its existing Systems Network Architecture net, it took the opportunity to evaluate the entire network and propose an overhaul.Because the city shared data Tiffany Nature Daisy Earrings and Necklace Set facilities in the Charlotte-Mecklenberg Government Center (CMGC) with the County of Mecklenberg, it was decided to include the county's SNA network in the scope of the redesign.
"It was getting cost-prohibitive to make all these point-to-point connections," said Guy Hutchins, the communications manager of the Communications Information Systems department. "We wanted one system that could handle all current needs as well as provide for future growth."
The new network, which is based on two fiber rings Elsa Peretti Teardrop Pendant Silver Set by a series of Fibronics International, Inc.'s MultiHubs, has allowed the city to reduce the number of costly leased lines it employs by multiplexing numerous lines onto a shared backbone, thereby saving thousands of dollars in monthly chargesBy integrating voice, video and data services on Fibronics' Unimux platform, Hutchins has been able to reduce hookup times because the net Tiffany Mini Bean Set consists of private fiber instead of public network facilities."Because we're not waiting on the local phone company and doing things ourselves, we can do in four hours what used to take us three weeks," he said.
It wasn't until Hutchins and his staff began a network inventory that they realized just how unwieldy the net had become. The SNA network is comprised of an IBM 4381 mainframe located at the CMGC data center that was connected to a 3725 front-end processor, which was supporting an undetermined number of local-and wide-area lines.
These lines branched out across five blocks to link Elsa Peretti Teardrop set --such as IBM 3174 cluster controllers and Application System/400s in several city buildings-to the CMGC data center, providing communications services to 26 city departments and more than 4,500 employees.The county had a separate but similarly configured network connecting its facilities.
"We had no idea how many communications devices existed when we first started," Hutchins said. "There were hundreds of connections between buildings, a conglomeration of mainframes and (other) IBM systems everywhere."Hutchins convinced city and county officials that it was time to integrate and consolidate communications facilities to reduce expenses and prepare for future needs.Charlotte then put the project out for bid and selected Fibronics' plan to provide a high-speed fiber network that would integrate a broad range of multivendor equipment."We were interested in getting the most bang for our buck from the new system, and the versatility of Fibronics' (MultiHub) gave us that," Hutchins said.The MultiHub is an intelligent fiber-optic hub with a 70M bit/sec bus that supports Ethernet and token-ring local-area Tiffany Sevillana Set and has time-division multiplexing capabilities.Hutchins used eight MultiHubs located in separate buildings to create two 70M bit/sec fiber rings--one connecting four city buildings and the other linking four county buildings.
The company also said it will begin offering Fiber Distributed Data Interface products by this fall and unveiled the second release of its network management software, which will give the 7700 enhanced security and fault-prevention capabilities plus visibility to IBM's NetView management system.
Bytex formed technology alliances with Wellfleet Communications, Inc. and CrossComm Corp. to Ten row Chain Heart Set two separate eight-port bridge/router modules for the hub--one geared largely toward token-ring local-area networks and the other toward Ethernets. Each will enable a user to route data packets at wire speed among as many as four token-ring, two Ethernet and two wide-area network links.
That's a vast improvement over typical two-port router cards that reside in Venetian Link Set intelligent hub and route traffic between two hub-attached LANs or from one LAN onto a WAN, said Janet Hyland, director of network strategy research at Forrester Research Inc., a Cambridge, Mass., consultancy.
"Today's hub-based routers are low-end devices with a limited number of port connections so users who need better performance must look to a stand-alone router. With the Bytex router, they can now get that high-performance routing right inside the hub," Hyland said. Although Dove Pendent Necklace and Earrings Set is the first, she expects a number of vendors will roll out so-called second-generation inter-networking hub modules over the next year.
Bytex's new routing modules will plug into one of four optional card slots in the 17-slot 7700 hub chassis and provide access to the device's 3G bit/sec matrix switch-based backplane. They will be able to dynamically establish links across the Tiffany & Co Atlas Set at full LAN speeds, offering support for such high-bandwidth applications as imaging.
That also enables the modules to support per-port routing, meaning data coming into one bridge/router port is sent out of its destination port without traversing intermediate networks. This contrasts with typical hub-based routing that--because of its two-LAN limitation--often requires multiple hops.
The modules will support the same popular LAN protocols as Wellfleet's and CrossComm's existing bridge/routers, as well as transparent bridging and the source routing and source routing transparent bridging algorithms.Bytex said the router will be available by year end. Pricing details were not available.
Bytex also announced plans to support FDDI LANs by year end. The Elsa Peretti Open Heart Pendant in Sterling Silver will first provide a stand-alone FDDI Work Group Concentrator that supports fiber-and copper-based FDDI links to the desktop and, by the first half of 1393, an FDDI router module for the 7700 hub that will give token-ring and Ethernet LANs access to an FDDI backbone.
On the net management front, the Series 7700 NMS Release 2.0 software includes four new management capabilites to enhance the management and security of the 7700 hub. One detects token-ring beaconing conditions, another helps isolate faults, and a third monitors Elsa Peretti 5 OPEN HEART Set connected to the LAN and notifies a net administrator of unauthorized additions or moves.
To enable net administrators to manage the net from a central IBM host management station, Series 7700 NMS is also equipped with software that enables it to send alert data to and receive commands from NetView.
At this point, migration from smart hubs to the third generation hub architecture has taken place. The third generation hub has provided a high-performance backbone to users with three levels of bandwidth to the desktop. How to cost effectively integrate smart hubs as the network grows while maintaining transparent connectivity to all users has also been shown. But as the network continues to grow, and more and faster devices are added to it, even the Item for price difference and shipping cost may become problematic insofar as the single FDDI backplane medium may itself become a bottleneck.
Once again, to relieve a bottleneck of this type, the traditional performance-improvement strategy of further segmenting the network will work. In this case, however, the segmentation must occur at the third generation hub backplane level. In other words, it will be necessary to segment the FDDI backplane to provide enhanced performance. Such segmentation can be accomplished merely by supplementing additional FDDI Elongated Teardrop bangle Engagement Ring set to the third generation hub backplane, and installing a different internetworking module that provides connectivity between backplane segments.
One approach to segmentation is to give network managers a wide degree of latitude in assigning independent network segments to different FDDI backplane segments, making it possible to supply optimal bandwidth distribution in the entire network. In practice, the "ideal" third generation hub will incorporate multiple FDDI backplane segments in the box. Moreover, because this approach inherently relies on the presence of bridging/routing capability in a third generation hub module, it has another important implication. This internetworking module also provides a means for connecting to external LANs/WANs. Thus, third generation Return to Tiffany Oval Tag Set internetworking offers the potential of extending functionality to isolated clusters of users that require it. For example, if there is a remote group of users who require private LANs, they can be connected to a third generation hub, which is then connected to the global network by means of module-based remote internetworking. In this situation, the true LAN/WAN integration is made possible.
Finally, network expansion does not stop at this point. Indeed, it is conceivable that the third generation hub's multiple FDDI backplane segments might themselves become a bottleneck in a future incarnation of the network. If this occurs, the need for more bandwidth could be accommodated by building an 1837 Collection Lock Pendant Set higher speed medium in a hub backplane, one that delivers up to 1 Gbps
Although the third generation hub has already had some impact on Round Link with Heart Clasp Set data communications network, we have only seen the beginning of such effects. Third generation hub products will support Ethernet, Token Ring, and FDDI, as well as provide transparent communications from one to another. In addition, they will provide internal segmentation for improved performance, and internal internetworking to connect these segments. They support technologies, such as private LANs and FDDI connectivity directly to the computer room and to the desktop. Finally, Third generation hubs are designed to increase performance and scalable bandwidth to the desktop for maximum investment protection.
Robert Roman is internetworking product line manager for 3Com Corporation's Network Systems Division. He has a master's degree in administration from Bowie State College.
Westborough, Mass.--Bytex Corp. last week disclosed plans to roll out by Tiffany Bead Set end new internetworking modules that will give its Series 7700 Intelligent Switching Hub routing capabilities approaching those of a stand-alone router.
Obviously, the second option will be much more cost-effective in almost every case. All that is required is a third generation hub module that combines Ethernet wiring concentration with an Ethernet-to-FDDI bridge to get the Ethernet signals onto the FDDI backplane. In the resulting architecture, each smart hub is connected to the third generation hub by means of a single Ethernet connection that occupies one port on an Ethernet concentrator module. That architecture is shown in Figure 2. (Figure 2 omitted)
This configuration offers several benefits. It provides an FDDI network backbone with the accompanying order of magnitude to increase backbone bandwidth. This was not available with the Ethernet backbone that preceded it, and this gain was realized Tiffany Atlas Man Dome Watch minimum disruption to the network by leveraging existing smart hub technology and the existing cabling plants. However, this architecture does not deliver a sufficient increase in bandwidth to hosts, work groups, or individual desktops that require it. To provide that bandwidth, the third generation hub and the network based on it must be extended one step further.
The secret to delivering increased bandwidth to the desktop lies in the fact that any third generation hub module used with the FDDI backplane has sufficient performance to accommodate the FDDI data rate. This means that any such module must Tiffany Elsa Woman Watch equipped with a high degree of processing capability. Given that this power must be present, additional capabilities can be designed into third generation hub modules.
The most direct way to supply additional performance to workgroups and individual power users is to further segment the existing network. Traditionally, this segmentation would be accomplished by adding internetworking devices, such as bridges, to the network. In this case, one can take advantage of the intelligence inherent in the third generation hub module to add high-speed Ethernet bridging within the module. The network architecture resulting Tiffany Atlas Woman Watch the use of such a module is depicted in Figure 3. (Figure 3 omitted)
This architecture segments each workgroup into a separate network, having its own 10 Mbps of bandwidth to share. Using this strategy, the performance potential of each hub increases without requiring any additional hardware other than the Ethernet bridge module in the third generation hub. The module can be used to provide a private LAM with 10 Mbps of bandwidth both to individual power users and to file servers in the computer room, by Tiffany Elsa Man Watch them directly to an Ethernet port in the third generation hub. With this architecture, available bandwidth to the desktop can be increased by simply moving the device's connection point from the smart hub to another in the same wiring closet. However, today's file servers are increasingly capable of bursting data in excess of the 10-Mbps rate. This raises the question: How can we accommodate these high-performance servers in the context of our growing network?
The answer requires the use of a higher speed link than Ethernet can provide, and since FDDI is already in 1837 Collection Lock Necklace Set in the third generation hub backplane, it is the logical medium to use to provide this link. A third generation hub module that offers direct FDDI connectivity is all that is needed and such a module can be created merely by incorporating FDDI cable concentration. The network architecture is derived from using a third generation hub with an FDDI concentrator.
High-speed file servers have direct FDDI access to the third generation hub Tiffany Atlas Man Watch to accommodate burst rates up to FDDI speeds. This can be accomplished just by installing a fiber optic link between the server and an FDDI concentrator port. Workstations that have bandwidth requirements exceeding 10 Mbps can be accommodated by the same technique. With this added capability, third generation hubs have been used with minimal change to the original network and now provide a level and range of bandwidth that can meet the needs of very demanding environments.
While answers to these questions will vary somewhat from one user organization to another and from vendor to vendor, there are some essential characteristics that every solution must have. For example, it is generally true that any answer to the bandwidth problem should be standards-based and of higher performance than either Ethernet or Token Ring. Fortunately, there exists a stable standard that fits the bill, namely Fiber Distributed Data Interface (FDDI), which makes it a logical choice as the basis for improving overall bandwidth. In addition to FDDI, more specific characteristics effectively define the design criteria for a Tiffany 1837 Collection Set generation hub; these additional characteristics include:
* seamless migration from Ethernet or Token Ring to FDDI. This in turn requires support for multiple network types such as Ethernet, Token Ring, and FDDI, and communications between them. Even though in many organizations one finds only two of the three network types, support for all three must be Paloma's X Earrings and Necklace Set to accommodate the range of equipment that may be found in today's corporate computing environments;* support for high-speed workstations, file servers, and hosts;* greater ability to isolate segments from unnecessary traffic to improve overall network performance;* enhanced flexibility and simplicity in network design and planning accomplished by providing both segment-to-segment and network type-to-network type internetworking right within the hub.
Although many potential designs will satisfy these criteria, for the purposes of this article it makes more sense to choose one idealized, highly simplified, and schematic design and show how it can be incorporated into a functional network. This hub design is based Heart Tag Toggle Link Set a back-plane that includes 100-Mbps FDDI media, to supply an order of magnitude increment in bandwidth over 10-Mbps Ethernet, or 4-or 16-Mbps Token Ring.
The ideal third generation hub includes modules providing wiring concentration, along with internetworking and network management functionality. Illustrations of these modules appear in appropriate figures to show how they can be added to the hub to Tiffany Cushion Toggle Necklace and Bracelet Set expanding network architectures.
As noted above, even networks built from scratch are likely to include new smart hub technology for cost reasons. Like existing networks, new networks must often provide a variety of performance levels. Using nothing but third generation hubs in a brand new network design would be prohibitively expensive. Since both scenarios require combining third generation hubs and smart hubs in a single topology, the problem of incorporating third generation hubs into a new network presents the same challenges as incorporating them into existing networks.
Existing networks, such as in Figure 1, may need to be upgraded to Tiffany Notes "I Love You" Heart Lock Charm Set the bandwidth that continuing network growth and new network applications will require. (Figure 1 omitted) When confronted with bandwidth demand, the network manager has the following choices:
* replace all existing networking equipment (e.g., hubs, adapter cards, etc.). This is equivalent to designing a new network with nothing but third generation hubs: while it delivers unprecedented performance, it is almost certain to be prohibited by its high cost.
* restructure the network by incorporating third generation hubs along with the Tiffany Atlas Woman Dome Watch equipment. That requires a way to connect any existing hubs to the FDDI backplanes of the third generation hubs.