14/11/2009 by David Slade.

A property management firm has been fined £1500 and ordered to pay costs of £2000 for two offences under fire safety legislation.

Solitaire Property Management Limited pleaded guilty to the offences at a hearing in Southampton Magistrates Court on 2 November. The company failed to respond to a number of requests for information under Article 27 of the Regulatory Reform (Fire Safety) Order 2005 about a block of flats in Southampton.

The prosecution was brought by Hampshire County Council solicitors and Solitaire Property Management received a fine of £750 per offence and were ordered to pay £1,000 to Hampshire Fire and Rescue Authority and £1,000 to Hampshire County Council.

Assistant chief officer Steve Hamm, head of community safety at Hampshire Fire and Rescue Service, said: “We require information about premises to enable us to carry out our enforcement action and improve the safety of the people of Hampshire. Failure to answer our letters constitutes an offence under the Fire Safety Order and Solitaire Property Management has today been found guilty of this offence

Posted in Reform (Fire Safety) Order 2005, Uncategorized | No Comments »

14/11/2009 by David Slade.

Category 5, 5e, and 6 copper wiring standards

The news on bandwidth
The need for increased bandwidth never ceases—the more you have, the more you need. Applications keep getting more complex, and files keep getting bulkier. It won’t be long before you need to increase the speed of your network.

Because unshielded twisted-pair UTP cable is by far the most common networking cable, let’s take a brief look at where UTP is headed.

The limits of Category 5
Category 5 (CAT5) cabling is good, solid cable for 100-Mbps LANs. The Category 5 standard has been around since 1991, so it’s well established. You’ll find existing Category 5 installations everywhere. What can Category 5 cable do, and what can’t it do?

If you still have a lot of 10-Mbps equipment, CAT5 cabling will serve your needs. It also handles 100-Mbps Fast Ethernet transmissions very well.

But if you’re running up against the performance limits of a 100-Mbps network, you’ll probably want to upgrade at least parts of your system fairly soon to Category 5e (CAT5e) or higher.

Category 5e: the improved Category 5
Category 5e, also known as Enhanced Category 5, or CAT5e, was ratified in 1999. It’s an incremental improvement designed to enable cabling to support full-duplex Fast Ethernet operation and Gigabit Ethernet.

The main differences between CAT5 and CAT5e can be found in the specifications. The performance requirements have been raised slightly in the new standard.

CAT5e has stricter specifications for Power Sum Equal-Level Far-End Crosstalk (PS-ELFEXT), Near-End Crosstalk (NEXT), Attenuation, and Return Loss (RL) than those for CAT5. Like CAT5, CAT5e is a 100-MHz standard, but it has the capacity to handle bandwidth superior to that of CAT5. With these improvements, you can expect problem-free, full-duplex, 4-pair Ethernet transmissions over your CAT5e UTP.

Category 6
The next level in the cabling hierarchy is Category 6 (CAT6) (ANSI/TIA/EIA-568-B.2-1), which was ratified by the TIA/EIA in June 2002. CAT6 provides higher performance than CAT5e and features more stringent specifications for crosstalk and system noise.

The quality of the data transmission depends upon the performance of all the components of the channel. So to transmit according to CAT6 specs, the jacks, patch cables, patch panels, cross-connects, and cabling must all meet CAT6 standards. (The channel includes everything from the wallplate to the wiring closet.) The CAT6 components are tested individually, and they are also tested together for performance. In addition, the standard calls for generic system performance so that CAT6 components from any vendor can be used in the channel.

CAT6 channel transmission requirements should result in a Power-Sum Attenuation-to-Crosstalk Ratio (PS-ACR) that’s greater than or equal to zero at 200 MHz.

In addition, all CAT6 components must be backward compatible with CAT5e, CAT5, and CAT3. If different category components are used with CAT6 components, then the channel will achieve the transmission performance of the lower category. For instance, if CAT6 cable is used with CAT5e jacks, the channel will perform at a CAT5e level.

Industry standards
The advantage of sticking to the industry standards is the knowledge that your cabling will be compatible with standards applications. But the standards are always being improved upon, and it takes time to ratify a new standard. Often, as with CAT6, the final standard may be different from the proposed standard.

Posted in cat5, Cat6, Cat5E | 1 Comment »

14/11/2009 by David Slade.

Category 4 is the performance level for voice and data transmission up to 20 MHz or 16 Mbps, such as 4-/16-Mbps UTP.

Both Category 3 and 4 are unsuitable for today’s high speed networking standards and will need to be replaced with Cat5 cable as a minimum if you intend to run 100baseT Ethernet.

Posted in Cat4 | No Comments »

14/11/2009 by David Slade.

Category 3 is the performance level for voice and data transmission up to 16 MHz or 10 Mbps, such as 4-Mbps Token Ring and 10BASE-T.

Both Category 3 and 4 are unsuitable for today’s high speed networking standards and will need to be replaced with Cat5 cable as a minimum if you intend to run 100baseT Ethernet.

Posted in Cat3, Uncategorized | No Comments »

14/11/2009 by David Slade.

Augmented Category 6 (CAT6a).

CAT6a is a 10-Gigabit Ethernet over copper proposal to the CAT6 standard. The IEEE published a draft standard (Std 802.3an) in October 2004. The draft calls for 10-Gigabit data transmission over a 4-connector twisted-pair copper cable for a distance of 100 metres on Class F or Class E-augmented copper cabling. Class E cabling requires a line-encoding scheme (PAM 12) and electronics to achieve the 10-Gbps transmission for 100 metres. Current CAT6 cabling systems may support 10-Gigabit Ethernet over limited distances.

The draft extends CAT6 electrical specifications from 250 MHz to 500 MHz. It also proposes a new measurement: Power-Sum Alien Crosstalk to 500 MHz. Alien Crosstalk is a coupled signal in a disturbed pair arising from a signal in a neighbouring cable.

Posted in Cat6A | 1 Comment »

14/11/2009 by David Slade.

IP Ratings (Ingress Protection)

The requirements of industrial environments are different from those of offices, and there have been a proliferation of industrial standards. The most commonly accepted are the Ingress Protection (IP) ratings developed by the European Committee for Electrotechnical Standardisation (CENELEC), which specify the environmental protection an enclosure provides.

An IP rating consists of two or three numbers. The first number refers to protection from solid objects or materials; the second number refers to protection from liquids and the third number, commonly omitted from the rating, refers to protection against mechanical impacts.

An IP67 rating means that the connector is totally protected from dust and is protected from the effects of immersion in 15 centimetres to 1 metre of water for 30 minutes.

Posted in IP Ratings (Ingress Protection) | No Comments »

14/11/2009 by David Slade.

Connecting peripherals with USB.

Because USB connections are hot-swappable, you can attach or remove peripherals without shutting down your computer.

A standard USB cable features two different kinds of connectors. A USB Type A connector plugs into a host device, such as your PC. The USB Type B connector plugs into the peripheral. Having two different types of connectors helps to prevent accidental loops.

To add more USB devices than your computer has USB connectors, you need a device called a USB hub. A hub provides additional connectors for your peripherals. Some USB devices (especially keyboards) feature built-in hubs, so you can plug yet another USB device (such as a mouse) into them.

You can plug hubs into other hubs to provide more connections. Each new layer of hub and cable is called a tier. USB supports a maximum of 5 tiers with up to 127 attached devices. Every other hub must be externally powered in order to supply enough power to attached peripherals.

A hub can also add additional distance between your PC and a peripheral. Each USB segment can be up to 5 metres (16.4 feet). Because USB supports up to 5 tiers, you can put peripherals a maximum of 25 metres (82 feet) from your PC.

Posted in USB | No Comments »

14/11/2009 by David Slade.

Benefits of T1 and E1.

If you manage a heavy-traffic data network and you demand high bandwidth for high speeds, you may need to send your data digitally over super-fast T1 or E1 communication lines.

Both T1 and E1 are foundations of global voice communication.
Developed more than 30 years ago and commercially available since 1983, T1 and E1 go virtually anywhere phone lines go, but faster.

T1 sends data up to 1.544 Mbps. E1 supports speeds to 2.048 Mbps. No matter where you need to connect—North, South, or Central America, Europe, or the Pacific Rim—T1 and E1 can get your data there—fast!

Both services provide flexibility for a multitude of applications.
Whether you need to drive a private, point-to-point line or a high-speed circuit; provide corporate access to the Internet or inbound access to your own webserver; or support a voice/data/fax/video WAN that extends halfway around the world, T1 or E1 can make the connection.

Both offer cost-effective connections.
In recent years, competition among telco service providers has led to increasingly more affordable prices for T1 and E1 services. In fact, most companies seriously considering a shift to T1 or E1 find they can negotiate even better rates with just a little comparative cost analysis.

Typical applications:

• Trunking of V.90 and ISDN remote connection to a central location.
• Accessing public Frame Relay networks for voice, fax, and data.
• Merging voice and data traffic. A single T1 or E1 line can give you several additional voice and data lines at no additional cost.
• Making LAN connections. If you’re linking LANs, a T1 or E1 line offers excellent performance.
• Sending bandwidth-intensive data such as CAD/CAM, MRI, CAT-scan images, and other graphics with large files.

Posted in T1 or E1 communication lines | No Comments »

14/11/2009 by David Slade.

Advantages of the PCI bus.

The high-performance PCI bus has both speed and interrupt-sharing advantages over the ISA bus.

The ISA bus implementation is based on edge-triggered interrupts. In computer electronics, everything is either 0 or 5 volts. Edge-triggered interrupts look for the transition (edge) from 0 to 5 volts or vice-versa. This makes it difficult to share interrupts because the PC may be busy when the transition (trigger) occurs. If so, the edge is not recognised and the request is not processed.

The PCI bus, however, provides level-triggered interrupts that see if the voltage is at 0 or 5 volts. Interrupt requests are always serviced no matter when they occur. This advantage means that a card in a PC bus will always outperform a similar card in an ISA bus.

Posted in PCI bus | No Comments »

14/11/2009 by David Slade.

Advantages of fibre optic line drivers.

For communications within a building or building to building, fibre optic cable is often the medium of choice. It may cost more, but it provides superior-quality data transmission.

fibre optic line drivers offer three main advantages over copper-wire alternatives for communications: superior conductivity, freedom from interference, and security.

Superior conductivity for increased performance—The glass core of a fibre optic cable is an excellent signal conductor. fibre cable yields very low signal loss with proper splices and terminations, and it can easily support data rates of 100 Mbps or more.

Immunity to electrical interference—fibre optic drivers use a nonmetallic conductor, so they neither pick up nor emit electromagnetic or radio-frequency interference (EMI or RFI).

Crosstalk (interference from an adjacent communication channel) is also eliminated, which increases the quality of the transmission.

Signals transmitted via fibre optic drivers aren’t susceptible to any form of external frequency-related interference. This means that fibre connections are completely immune to damaging power surges, signal distortions from nearby lightning strikes, and high-voltage interference. And fibre cable doesn’t conduct electricity, so it can’t create electrical problems in your equipment.

Signal security—Electronic eavesdropping requires the ability to intercept and monitor the electromagnetic frequencies of signals traveling over copper data wire. Because fibre optic drivers use a light-based transmission medium, they’re completely immune to electronic bugging.

Posted in Fibre optic line drivers | No Comments »

14/11/2009 by David Slade.

Remote access servers (RASs) are high-level intelligent devices with multiple asynchronous communication ports that connect to modems and provide remote users with dial-in access to a central site network.

You can configure your RAS to operate via remote control or remote node access.

Remote control operation enables remote users to send keystroke data and receive screen output from the central site. The actual processing takes place inside the communication server. Remote node access enables the remote user to become a network node and all remote workstations to function as if they were connected locally.

A fixed-port remote access server has a network connection to your LAN and one or more asynchronous RS-232 ports that connect to external modems. It usually comes equipped with 4, 8, or 16 async ports and is easy to install, support, and maintain. These devices are ideal for traveling workers who don’t have a remote office but who need connections to the corporate network for short periods of time.

For configuration flexibility, scalability, and remote wide-area connection options, choose a modular remote access server that you can change as your network grows. Most modular RASs accept a variety of modules, including:

• High-density async RS-232 modules that connect to external modems or ISDN terminal adapters. These modules typically have eight or more ports.
• High-density modem cards that usually incorporate eight modems on a single card, enabling you to consolidate equipment costs, increase reliability, and simplify management.
• Digital modules that enable you to make direct connections to high-speed digital lines. Instead of using multiple dialup lines, you can use these devices to bring a single high-speed digital phone line—ISDN— to your equipment.

The best way to determine what type of RAS you need—or whether you need a router or a RAS—is to identify what remote solution will meet your connectivity requirements.

Posted in Remote access servers (RASs) | No Comments »

14/11/2009 by David Slade.

Power over Ethernet (PoE).

Powering remote Ethernet devices can be a problem when you need to find an AC power outlet to plug a bulky transformer into. But with Power over Ethernet (PoE) you don’t need a power outlet because your Ethernet device draws power from the same Ethernet UTP cable that connects it to the network. You simplify installation by getting power where you need it with PoE.

What is PoE?
The seemingly universal network connection, CAT5 cable, has another role to play: to provide electrical power as well as data. Power over Ethernet (PoE) was ratified by the Institute of Electrical and Electronic Engineers (IEEE) in June 2000 as the 802.3af-2003 standard. It defines the specifications for the transmission of electrical power over CAT5 data cable.

This standard promotes the delivery of low levels of power—just 13 watts or less—over data lines to PoE devices such as IP telephones, wireless access points, Web cameras, and audio speakers. PoE is also ideal for applications such as video surveillance, building management, retail video kiosks, smart signs, vending machines, and retail point of information systems.

By eliminating the need to install separate outlets for data and power, users can save up to 50% in installation costs.

How does PoE work?
Very simply, CAT5 Ethernet cable consists of four twisted pairs of cable. Only two pairs are used for 10BASE-T and 100BASE-TX Ethernet data transmission; the remaining pairs are available for power. The PoE standard offers two options for using the twisted pairs for power. The first option sends the electrical power through the spare pair. The second option uses the data pairs for both power and data.

The data and power transmissions don’t interfere with each other either. Electricity has a low frequency of 50 - 60 Hz or less, and data transmissions have frequencies that can range from 10 million to 100 million Hz. Because data and electricity are at opposite ends of the frequency spectrum, they can travel over the same cable.

PoE devices
To install Power over Ethernet, you need to add a PoE injector (also known as Power Sourcing Equipment or PSE), to insert DC voltage onto the CAT5 cable. The injector is usually installed near the Ethernet switch and may be a single-port model that inserts power onto only one cable or may be a PoE hub, which inserts power onto multiple cables.

At the other end of the powered CAT5 Ethernet cable, you need a way to get the power from the Ethernet cable and back into a device. Many network devices are now made as PoE-compatible devices that can take power directly from the CAT5 cable. These devices are sometimes also described as active Ethernet compatible.

Additionally, you can power some network devices that aren’t PoE compatible by using a device called a picker or a tap. It “picks” the DC voltage from the CAT5 cable and routes it to the device.

PoE applications and benefits:

• Use one set of twisted-pair wires for both data and low-wattage appliances.
• Save money by eliminating the need to run electrical wiring.
• Easily move an appliance with minimal disruption.
• If your LAN is protected from power failure by a UPS, the PoE devices connected to your LAN are also protected from power failure.
• Supports the addition of end-span, standalone, and mid-span devices.
• As PoE becomes more common, the 8-pin modular connector will become the industry-standard power jack.

Posted in Cat5E, 10BASE-T, 802.3af-2003, Power over Ethernet (PoE), 100BASE-TX | No Comments »

14/11/2009 by David Slade.

Fibre Optic Standards Explained:

Several IEEE standards have been established for Ethernet over fibre optic media. 10BASE-FL, one of the standards defined by the IEEE, allows Ethernet to operate at 10 Mbps over fibre optic cable. 100BASE-FX and 100BASE-SX both allow Ethernet speeds of 100 Mbps. 100BASE-FX operates at higher wavelengths than 100BASE-SX and can also be used with single-mode fibre cable.100BASE-SX operates at a wavelength of 850 nm and can only be used with multimode cable. The newest standards-1000BASE-SX and 1000BASE-LX -define speeds of 1 Gigabit and distances up to 5 kilometres. Actual distances that can be achieved with Media Converters can be much higher.

Posted in 100BASE-SX, 1000BASE-SX, 1000BASE-LX, 10BASE-FL, Fibre Optic Standards, 100BASE-TX, 100BASE-FX, 1000 BASE-T | No Comments »

14/11/2009 by David Slade.

Media converters

• Seamlessly integrate 10, 100, and 1000 BASE-T, ThinNet, Thicknet and fibre optic cabling.
• Inexpensively connect half- or full-duplex 100BASE-TX and 100BASE-FX!
• Switch between different wiring systems without adding to your overall network repeater count.
• Convert to fibre and run cables across an extra-long distance-up to 50 kilometres or more!
• Have an Ethernet switch with RJ-45 ports? No problem! Use a converter to attach legacy AUI and BNC or new fibre segments.

What are Media Converters?
Media converters are simple networking devices that enable you to interconnect networks or network devices with different speeds, operation types, modes and media types. Operation addresses half- and full-duplex dissimilarities. Mode addresses different wavelengths in a fibre optic environment. And media type can be multimode, single-mode or twisted-pair cable.

Benefits of Media Converters:
Media converters play an important role in today’s multiprotocol, mixed-media networks. For example, LAN administrators can deploy media converters to integrate fibre optic cabling and active equipment into existing copper-based, structured cabling systems while achieving significant cost savings. In general, media conversion can deliver the following benefits for your network environment:

Cost Reduction
You can use media converters with cost-effective Ethernet switches to do the same job as expensive hybrid media switches and reduce your overall networking costs in the process. Media converters can also be used with fibre optic cabling to bridge the last mile in your network or to establish a WAN connection up to 100 kilometres. This type of media converter solution can cost significantly less than one that relies on higher-layer devices such as routers or switches.

Investment Protection
Media converters enable you to protect your existing network investment. As simple network devices, media converters can easily be located or relocated to other areas within the installation, further leveraging the original investment. Additionally, they extend the productive life of your fibre and copper wiring plants by being able to interconnect different devices supporting various media types (coaxial cable, twisted pair, single-mode or multimode fibre), different wavelength modes (850 nm, 1310 nm or 1550 nm) or dissimilar speeds (10 Mbps, 100 Mbps or 1000 Mbps).

Flexibility and Simplification
Media converters offer the flexibility of combining copper with 850 nm and 1300 nm multimode fibre and 1310 nm and 1550 nm single-mode fibre. Slide-in media conversion cards for all cable types can reside in one media conversion chassis. With protocol transparency, Ethernet speed can be supplied anywhere in the network-local or remote-whether it’s a LAN or the WAN environment. Every device can also be smoothly integrated into your workgroup or the enterprise-wide network, regardless of the type of bit rate transparency or the bit rate conversion that’s supported.

Ease of Use and High Availability
Media converters are much easier to handle and to manage than higher-layer devices. Configuring and installing redundant solutions is neither complex nor cost intensive. And by adding management functions to your media converters, you can minimise downtime and make troubleshooting easier.

What Kinds of Media Converters Exist?

Basic Media Converter
A basic media converter is a Layer 1 device that transparently passes through all information. It has a very low path-delay value and does not count as a repeater. Basic media converter functions may include FibreAlert, LinkLoss and single-strand fibre conversion. Along with its all-transparent behaviour, a basic media converter’s key advantage is its low cost.

Switched Media Converter
A switched media converter not only converts media types and fibre mode but also speed and duplex mode. As the name implies, a switch is integrated into the converter to provide additional functionality. This switch function is its key advantage and often enables you to securely combine multiple Ethernet interfaces onto one fibre or prioritise traffic over the link.

Managed Media Converter
A managed media converter can be controlled and monitored locally and remotely. It can support command line interface, Telnet connections or SNMP functions for integration into an element manager or a management platform. Its key advantages are easier troubleshooting and reduced downtime.

Possible Media Converter Features:

LinkLoss™ Feature
When either a twisted-pair or a fibre link is broken, the information about this link loss is transferred to the other media link. For example, when a cable breaks on the fibre segment of a conversion, LinkLoss detects the error and passes this information to the twisted-pair segment. This results in a loss of link on the remote twisted-pair device. If LinkLoss is enabled on that device, the device’s green Link LED goes out, informing the local supervisor that there’s something wrong with the link.

FibreAlert™ Feature
What if only one strand of a fibre segment is broken? The FibreAlert feature enables the media converter at the receiver end to detect this type of link loss. The media converter stops transmitting data and a link signal until it begins receiving a signal or link pulse again. If there’s no signal or pulse, Link LEDs on the media converters at both ends of the fibre segment go out, indicating a fault somewhere in the segment. This way, a local site administrator is notified of a cable fault and can quickly locate it.

Wavelength Division Multiplexing (WDM) Feature
Black Box’s new WDM media-conversion products enable you to double your fibre optic plant capacity by using Wavelength Division Multiplexing technology. With a WDM converter, you can send more than one optical signal through the same fibre strand. WDM modulates each of several data streams onto a different part of the light spectrum. In this way, it increases the amount of data that a fibre optic cable can transport.

There are two flavours of WDM media converters: one fibre link and single-strand fibre. The one-fibre link version transports two links onto one duplex fibre link. The single-strand fibre version transports one link over a single strand of fibre.

Posted in LAN, BNC, Media Converter, LinkLoss, Wavelength Division Multiplexing (WDM), FibreAlert, RJ45, 100BASE-FX, ThinNet, 1000 BASE-T, Thicknet, fibre optic cabling, 100BASE-TX, WAN (wide area network) | No Comments »