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FAQ - Networking Products

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(We wish to thank Unicom for their contributions.)


  1. Why Choose Fast Ethernet over Ethernet?
  2. What is the difference between hubs and switches?
  3. What is the benefit of a Switch?
  4. Where on the network is a Switch most effective?
  5. How can I connect an existing Ethernet network with a Fast Ethernet Network?
  6. How do I speed up an existing fast Ethernet network?
  7. How do I connect two hubs together?
  8. How many Ethernet Hubs can I connect in a network?
  9. What is port partition?
  10. What kind of cable should be used to connect Fast Ethernet Networks?
  11. What is a common cause of two computers not seeing each other in a network?
  12. What is an Auto-Negotiation (N-Way) function in relation to 10/100 ports?
  13. What are the requirements for Full Duplex?
  14. What is a converter?
  15. Can a 100Base-TX/100Base-FX Converter be used with a Fast Ethernet Hub or Fast Ethernet Switch?
  16. How far can I connect by using Multi-mode or Single Mode fiber optic cable?


Why Choose Fast Ethernet over Ethernet?
Fast Ethernet is 10 times faster (100Mbps) than Ethernet networks (10Mbps) and provides faster throughput for video, multimedia, graphics, Internet surfing, and other speed-intensive applications. It also has stronger error detection and correction capability. Fast Ethernet hardware is available at prices that are only slightly higher than Ethernet hardware.


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What is the difference between hubs and switches?
A hub is a device where bandwidth is shared among all devices connected to it. A switch, however, is a device where each port has it’s own dedicated bandwidth. For example, a 16-port 10/100Base-TX switch (half duplex) would have an 100Mbps bandwidth to support each port whereas a hub would share that same 100Mbps among all 16 ports; or about 8Mbps to eachport. Also the linking maximum for hubs is two units while a switch can accommodate virtually an unlimited number of uplinked units.


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What is the benefit of a Switch?
Since a hub shares all it’s bandwidth among it’s ports, it is generally slowerand more susceptible to collisions and errors. A switch however, with it's owndedicated bandwidth, creates a separate collision domain by dedicating a full100Mbps line segment through each port. As well as making a switch faster andmore stable, this feature provides virtually unlimited expansion, overcoming thehub uplink limitations in 10Base-T and 100Base-TX networks.


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Where on the network is a Switch most effective?
Connect a switch as a backbone to a local file server, a print server, a power user, another UNICOM switch, or use it as you would a UNICOM hub.


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How can I connect an existing Ethernet network with a Fast Ethernet Network?
A Fast Ethernet Switch is the best solution for Ethernet and Fast Ethernet connection due to it’s built-in Auto-Negotiation (10/100) feature.


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How do I speed up an existing fast Ethernet network?
The solution to this problem is a Fast Ethernet switch. Fast Ethernet networks normally operate with shared bandwidth, which means that the network's overall speed is spread out across the available number of nodes (devices). If you have a hub with 5 nodes attached to it and the total bandwidth of the network is 100Mbps, then each node receives 100/5, or 20Mbps, of bandwidth. If you have only a few nodes, shared bandwidth isn't a problem. However, imagine spreading 100Mbps across 30 nodes — even at Fast Ethernet speeds, the network could slow significantly during peak traffic periods. A switch transforms a shared network into a switched network; each node accesses the network at the maximum bandwidth speed. For example, if you have five ports, each port receives 100Mbps access through a Fast Ethernet Switch. Switches also speed up network access due to their advanced addressing technology. In a shared network, data packets bounce around the network until they find their destination. Switches examine each data packet individually and direct them only to their intended destinations. Not only can switches improve a Fast Ethernet network's efficiency, but when used in conjunction with a 10Base-T network, they can reduce wasted bandwidth, increasing performance as much as 40%.

Switches come in all shapes and sizes. Just like hubs, they are available in both desktop and rack mountable versions that can be integrated with both network adapters and hubs. If your network demands optimum speed for video, graphics, multimedia, or other intensive applications, switches may provide an extra boost.


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How do I connect two hubs together?
Connecting two hubs together requires a crossover connection either by using a crossover cable connected to any regular port or a pin-to-pin cable connected to the uplink port.


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How many Ethernet Hubs can I connect in a network?
A maximum of two Class II Ethernet Hubs can be used within one collision domain. This is called cascading. However, when hubs are stacked, they function as one and four hubs can be used.


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What is port partition?
Port partition relativeto UNICOM Hubs: The IEEE states that ports can partition for excessive collisions and/or bad transmissions. Faulty or inappropriate cable or a defective hub port or adapter usually causes these conditions.


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What kind of cable should be used to connect Fast Ethernet Networks?
For 100Base-TX (100Mbps) networking, Category 5 or higher grade UTP cable should be used; e.g., Category 5 or Category 5e UTP cable.


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What is a common cause of two computers not seeing each other in a network?
To connect two computers together directly without a hub, the UTP cable has tobe a crossover. A common mistake is to use a pin-to-pin cable. Make sure a crossover cable is used.


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What is an Auto-Negotiation (N-Way) function in relation to 10/100 ports?
Auto Negotiation is a mechanism designed for 10Base-T/100Base-TX/100Base-T4 connections that examines the incoming devices and configures the switch port to the proper speed (10Mbps or 100Mbps). It acts like a rotary switch that automatically cycles to the correct speed in the following sequence:


  1. 100Base-TX, Full Duplex
  2. 100Base-T4
  3. 100Base-TX
  4. 10Base-T, Full Duplex
  5. 10Base-T

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What are the requirements for Full Duplex?
For a network to support Full Duplex, both devices must support and be configured for Full Duplex. Full Duplex is intended to increase the speed of a direct link between two devices; i.e., between switches or between a workstation and a switch. Switches support Full Duplex; hubs do not. Configuring an adapter for Full Duplex operation while connected to a hub could cause issues such as slowness or device drop-offs.


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What is a converter?
A converter is a device that repeats and/or converts the signal from different media within the same transmission speed, e.g., 100Base-TX to 100Base-FX or 10Base-2 to 10Base-T.


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Can a 100Base-TX/100Base-FX Converter beused with a Fast Ethernet Hub or Fast Ethernet Switch?
It can be used with either. However, the distances vary for both. You can have up to 2,000 meters of Multi-mode fiber optic cable with Fast Ethernet under Full Duplex mode, but only up to 200 meters with a Fast Ethernet Hub under half-duplex mode. Note: Fast Ethernet Hubs support half-duplex mode only.


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How far can I connect by using Multi-mode or Single Mode fiber optic cable?
Multi-mode fiber optic cable connects up to 2,000 meters when the network is operated in Full Duplex mode. It can connect up to only 200 meters in Half Duplex mode. Single mode fiber optic cable can transmit from 15,000 meters to 60,000 meters, depending on hardware and configuration.


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