Frequently asked questions
- What is Wireless/Computer Networking?
- What is the difference between a hub and a switch? Which one is better for my network?
- What is the difference between the types of cable - UTP, Patch, Stranded, Solid?
- What are the maximum lengths for cables?
- Is Cat 5e backwards compatible?
- Can I run Cat 5e Ethernet cable outside?
- What is attenuation?
- What are the possible ways of data exchange?
What is Wireless/Computer Networking?
In the world of computers, networking is the practice of linking two or more computing devices together for the purpose of sharing data. Networks are built with a mix of computer hardware and computer software.
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What is the difference between a hub and a switch? Which one is better for my network?
A switch is effectively a higher-performance alternative to a hub. Technically speaking, hubs operate using a broadcast model and switches operate using a virtual circuit model. When four computers are connected to a hub, for example, and two of those computers communicate with each other, hubs simply pass through all network traffic to each of the four computers.
Switches, on the other hand, are capable of determining the destination of each individual traffic element and selectively forwarding data to the computer that actually needs it. By generating less network traffic in delivering messages, a switch performs better than a hub on busy networks.
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...more about hubs & switches
Although hubs and switches both glue the PCs in a network together, a switch is more expensive and a network built with switches is generally considered faster than one built with hubs. Why?
When a hub receives a packet of data at one of its ports from a PC on the network, it transmits (repeats) the packet to all of its ports and, thus, to all of the other PCs on the network. If two or more PCs on the network try to send packets at the same time a collision is said to occur. When that happens all of the PCs have to go though a routine to resolve the conflict. The process is prescribed in the Ethernet Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol. Each Ethernet Adapter has both a receiver and a transmitter. If the adapters didn't have to listen with their receivers for collisions they would be able to send data at the same time they are receiving it (full duplex). Because they have to operate at half duplex (data flows one way at a time) and a hub retransmits data from one PC to all of the PCs, the maximum bandwidth is 100 Mhz and that bandwidth is shared by all of the PC's connected to the hub. The result is when a person using a computer on a hub downloads a large file or group of files from another computer the network becomes congested. In a 10 Mhz 10Base-T network the affect is to slow the network to nearly a crawl. The affect on a small, 100 Mbps (million bits per scond), 5-port network is not as significant.
Two computers can be connected directly together in an Ethernet with a crossover cable. A crossover cable doesn't have a collision problem. It hardwires the Ethernet transmitter on one computer to the receiver on the other. Most 100BASE-TX Ethernet Adapters can detect when listening for collisions is not required with a process known as auto-negotiation and will operate in a full duplex mode when it is permitted. The result is a crossover cable doesn't have delays caused by collisions, data can be sent in both directions simultaneously, the maximum available bandwidth is 200 Mbps, 100 Mbps each way, and there are no other PC's with which the bandwidth must be shared.
An Ethernet switch automatically divides the network into multiple segments, acts as a high-speed, selective bridge between the segments, and supports simultaneous connections of multiple pairs of computers which don't compete with other pairs of computers for network bandwidth. It accomplishes this by maintaining a table of each destination address and its port. When the switch receives a packet, it reads the destination address from the header information in the packet, establishes a temporary connection between the source and destination ports, sends the packet on its way, and then terminates the connection.
Picture a switch as making multiple temporary crossover cable connections between pairs of computers (the cables are actually straight-thru cables; the crossover function is done inside the switch). High-speed electronics in the switch automatically connect the end of one cable (source port) from a sending computer to the end of another cable (destination port) going to the receiving computer on a per packet basis. Multiple connections like this can occur simultaneously. It's as simple as that. And like a crossover cable between two PCs, PC's on an Ethernet switch do not share the transmission media, do not experience collisions or have to listen for them, can operate in a full-duplex mode, have bandwidth as high as 200 Mbps, 100 Mbps each way, and do not share this bandwidth with other PCs on the switch. In short, a switch is "more better".
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What is the difference between the types of cable - UTP, Patch, Stranded, Solid?
UTP stands for Unshielded Twisted Pair. It is a cable type with pairs of twisted insulated copper conductors contained in a single sheath. UTP cables are the most common type of cabling used in desktop communications applications.
Stranded cable has several small gauge wires in each separate insulation sleeve. Stranded cable is more flexible, making it more suitable for shorter distances, such as patch cords.
Solid has one larger gauge wire in each sleeve. Solid cable has better electrical performance than stranded cable and is traditionally used for inside walls and through ceilings - any type of longer run of cable.
Patch Cables are made of stranded copper conductors for flexibility. This construction is great for the flexing and the frequent changes that occur at the wall outlet or patch panel. The stranded conductors do not transmit data signals as far as solid cable.
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What are the maximum lengths for cables?
For solid UTP:
- Fast Ethernet 100baseT 100 Meters (328 feet)
- Twisted Pair Ethernet 10baseT 100 Meters (328 feet)
Recommended maximum lengths for Patch Cables made from stranded cable:
- Fast Ethernet 100baseT 10 Meters (33 feet)
- Twisted Pair Ethernet 10baseT 10 Meters (33 feet)
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Is Cat 5e backwards compatible?
Yes it works with any 10BaseT or 100BaseT network cards and hubs.
Cat 5 is also upwardly compatible with Cat 5e, however your network throughput will only be as fast as the slowest part.
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Can I run Cat 5e Ethernet cable outside?
Cat 5e cable is not rated for outdoor use, however it can generally be used without a problem. If possible, run the cable through some kind of conduit to prevent moisture or an attractive site for lightning to strike. You should be able to find gray PVC conduit suitable for cable at any hardware store. Remember, 100 Meters is your max distance, without some kind of hub, bridge or amplification.
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What is attenuation?
The degeneration of a signal over distance on a network cable is called attenuation.
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What are the possible ways of data exchange?
- Simple
- Half-duplex
- Full-duplex
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