Store More Information With 2D Barcodes

Barcodes have for many years now been the standard way of tagging products for easy identification. RFID has been threatening for some time to take over, but to date has failed to make really significant in-roads and gain mass market appeal. In the meantime, the humble black and white stripes have not rested on their laurels, with new barcode symbologies being developed over the years. One of the most significant developments of recent years has been the continuing rise of 2D barcodes, perhaps most noticeably in the last few months in the form of (quick response) QR codes on adverts.

2D Barcode Fundamentals

What sets 2D barcodes apart is the amount of data they can store compared to a traditional 1D or linear barcode. Linear barcodes generally store a key piece of information about an object - a part number or batch number - with further details such as description, expiry date, etc., only being available once received from a database.

2D barcodes allow far greater amounts of information to be stored within the same area as a linear barcode, or allow the same information to be stored in a much smaller space. Thus, the holding of part number, expiry date and batch number within a small, single barcode becomes perfectly feasible.

2D Symbology Types

Stacked symbologies contain multiple rows of linear bars and spaces - effectively a stack of two or more linear barcodes - for example, PDF417. Stacked barcodes can be read by the majority of laser scanners, laser imagers and area imagers (subject to symbol size).

Matrix symbologies encode data in a grid of dark and light components, with the position of each component relative to the barcode centre being significant. Due to their compact size matrix symbologies are particularly suitable for marking small items. They can, however, only be read by area image scanners.

Application of 2D Barcodes

Whereas a few years ago 2D barcodes were widely regarded as a niche technology, they have more recently become more mainstream. Thanks to their ability as a portable mini-database to hold multiple pieces of information about an object, business processes can benefit from having extensive information immediately available - better stock rotation based on expiry date information, more efficient tracking in the supply chain etc. Small barcode size can reduce packaging volumes, improve first time scan rates and even enable barcode labelling of small, loose and irregularly shaped items. It's no wonder that 2D barcoding is really taking off in manufacturing, pharmaceuticals, healthcare and logistics.

Looking Forward

Whilst 2D barcodes have suffered in the past from the required area imagers being expensive and being unable to scan barcodes at distance, technology inevitably moves on and overcomes any difficulties. With the recent advent of low cost area imagers that can scan at greater distances with acceptable first-time scan rates, it seems it will only be a matter of time before 2D barcodes become dominant (until the next great revolution).

What Is an Ethernet Switch?

An Ethernet switch is a networking device that is used in almost all data networks to provide connectivity for our networking devices. Prior to the invention of the Ethernet switch, our Ethernet data networks used either Repeaters or Hubs to build Local Area Networks.

Before Ethernet Switches, a lot of networks used coaxial cable for local network connections, in a network topology that became known as a bus network. The most common bus networks used two early Ethernet cabling standards, which were the 10Base5 and 10Base2 coaxial cable standards. The 10Base5 networks were often referred to as Thicknet, while the 10Base2 networks were known as Thinnet. All network devices such as computers and servers were connected to a segment of cable in what was known as a "shared environment", or more commonly a collision domain. This type of network relied on data being broadcast across the media to all connected devices.

The invention of the hub made it easier for devices to be added or removed from the network, but an Ethernet network using a Hub was still a collision domain, where collisions were way of life. Ethernet network interface cards were designed to use CSMA/CD and detect and deal with collisions. Unfortunately collisions do have an effect of slowing down a network and make that network less than efficient. A Hub is said to be a Layer-1 device as it has no real intelligence, and in fact it is really just a multi-port repeater, with data entering one port being duplicated when sent out the other ports. The reference to Layer 1 is to the bottom layer of the OSI 7 Layer reference model.

The Hub was eventually replaced by the Ethernet switch as the most common device in Local Area Networks. The switch, which is a much more efficient device, is said to be a more intelligent device than a Hub because it is able to interrogate the data within the Ethernet Frames, whereas a hub just retransmits the data. With Ethernet, we use 48-bit MAC Addresses when labelling specific physical network interfaces, and an Ethernet frame of data contains both the Source and Destination MAC Addresses to enable data to be routed and switched from one specific physical interface to another.

An Ethernet switch has 3 main functions, which are:

Address Learning

Forwarding and Filtering

Loop Avoidance.

Address Learning

When a data frame enters through a port on a switch, the Ethernet Switch reads the Source MAC Address and adds that address to a MAC Address Table. This table is often referred to as Content Addressable Memory (CAM). Within the table the MAC Address is associated with the physical port on the switch to which the network device is attached. The switch now knows which port to forward data to when an Ethernet frame arrives from elsewhere in the network, because it checks the destination MAC Address, and looks for a match in the table. The Destination MAC Address is therefore used by the Ethernet Switch to forward data out of the correct port to reach the correct physical interface.

Forwarding and Filtering

When a switch receives an Ethernet frame, it will read the Destination MAC Address in order to determine which port to forward the data out of. When a switch receives an Ethernet frame with a Destination MAC Address that is not referenced in the table, it floods that frame out of all ports in an attempt to reach the correct physical interface. If the correct device responds, then the switch will now know where that MAC Address resides, and is therefore able to add that address to the table for future reference.

LoopAvoidance

Almost all modern switches run a protocol known as the Spanning-Tree Protocol, or STP. STP was originally a proprietary protocol developed by DEC, but is now an IEEE Standard known as IEEE 802.1d, which was later revised to IEEE 802.1w (Rapid Spanning-Tree Protocol). The role of Spanning Tree is to detect and manage loops in a network, which can be a big problem by allowing duplicate frames to be delivered, and cause the MAC Address Table to become unstable. In severe cases network loops will cause a network to be over subscribed and eventually be overwhelmed by the amount of data. Spanning-Tree allows network designers to build redundancy and resilience into a network, safe in the knowledge that any physical or logical loops created will be managed by the Spanning Tree Protocol.

You will hear the terms Layer 2 and Layer 3 Switch, what do they mean?

A Layer 2 Ethernet switch operates by performing like we described in the previous paragraphs. The Layer 2 name comes from the fact that it operates at Layer 2 of the OSI 7 Layer Reference Model. This Layer is often referred to as the Data-Link Layer, and it is the layer that Ethernet is described, and where MAC Addresses are used.

So what is a Layer 3 Ethernet Switch?

A Layer 3 Ethernet Switch combines the features and functions of a basic Layer 2 switch, with features normally associated with a Router. In fact, it is probably easy to describe a Layer 3 switch as a switch and a router combined. A Layer 3 switch will have either a number of fixed Ethernet ports that have layer 3 IP Addresses associated with them, or more commonly, configurable ports that can be Layer 2 or Layer 3 as desired. All but the smallest home consumer Layer 2 switches allow the configuration of VLANs (Virtual Local Area Networks), but are not able to directly route traffic between multiple VLANs. In order to do this, the addition of a Layer 3 device such as a Router would be needed. A Layer 3 switch can perform this function in addition to tradition Layer 2 switch functions.

When purchasing an Ethernet switch, you need to determine what its role will be in the network, and whether or not Layer 3 functions will be required. Normally a Layer 3 Ethernet switch will be more expensive than a comparable Layer 2 device, so it would be an unnecessary expense to employ a Layer 3 switch when a Layer 2 switch would suffice.

Ethernet switches have evolved since the first simple devices were introduced, and some have a lot of additional features and support a wide range of ever increasing network protocols. Some of these features and protocols will be discussed in future articles.

Role of Help Desk Services in Large and Small Organizations

In help desk services the queue managers as well as the issue tracking system play a vital role. The issue tracking system maintains the list of issues which have to be addressed by the managers time to time, who further prioritizes and does a follow up accordingly. Hence, these help desk services are of great use for the small and big organizations as well.

The help desk services are useful in providing information and also support which helps in solving issues related to computers and similar other products. Normally, the organizations offer the help desk services through internet, email or toll-free number. There are even certain in-house services to offer the similar kind of aid for the customers. Few of the educational institutions conduct classes for helping various sections of people to solve the issues. A general help desk has many functions. It offers the customers a unique source of contact through which they can address the various issues raised by their customers. It makes use of software which tracks the major issues which the customers request via a unique number provided mainly for help desk services.

Bigger help desk services manage various levels to address the questions raised by the customers depending on the intensity of the problem. At the primary level, the common problems raised by the customers are taken care of. If this problem is not solved at the primary level it will be passed on to the next level which may provide the necessary tools for solving that particular problem. Few companies maintain even third and another higher level to address problems relating to software.

These help desk services are performed by a team or a single person who is known as queue managers as well as queue supervisors. The manager of the help desk services has to prioritize the issues which come up to him/her through the tracking process. Usually people working in the larger help desks are very experienced professionals who have the capacity to take up challenges in various fields and problems. The queue supervisor gives each team an issue which they have to work out and come up with a solution. Certain problems are sometimes forwarded to experienced people or analysts who have knowledge on the particular topic. These analysts have certain functions to perform like taking up phone calls, replying to the questions asked through emails etc. but these functions are fulfilled by them only in a particular time limit everyday.