Category Archives: Networks

The Benefits Of Using Switches Over Hubs


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It’s very much possible to create a computer network based only on hubs, but there are a few reasons why this is not recommended, despite the fact they’re cheaper than switches. Switches are essentially the same as hubs, but just a little bit smarter. This article discusses the small difference between hubs and switches, as well as the benefits that using switches instead of hubs brings.

Hubs are widely thought of as dumb peices of networking equipment. They do their job of forwarding information across a network, but that’s all they’re capable of doing. The way they forward information is very wasteful, in terms of adding traffic onto the network. If you have 10 PC’s connected to a 10 port hub and the PC connected to port 1 wants to talk to the PC connected to port 5, the hubs’ only option is to broadcast the information down all of the ports, so every PC is sent the information despite it only being addressed to the PC on port 5. You can see how wasteful this is.

A switch is slightly different, they are more intelligent; the switch maintains a table, called an ARP table (Address Resolution Protocol) of all PC’s connected. The table cross references each port on the switch with the hardware address, also known as the MAC address, of the device connected to that port. Using the example above, if the PC on port 1 wants to talk to the PC on port 5, it sends the information to the switch including the MAC address of the PC on port 5, the switch then looks up the location of the the PC based on the ARP table and the MAC address provided; the switch knows to forward the information to port 5 only. This uses up less resources and creates less traffic on the network.

Sure you could have a small network of 10 PC’s running perfectly fine using a hub, but that’s missing the point. As a network grows, the more important it becomes to manage the amount of traffic on the network. This is a fundamental concept of network design. We should understand from this that a network design based on hubs suffers from poor scalability. Another benefit of using switches instead of hubs is that they virtually eliminate collisions; a collision occurs when two computers try to transmit information on the same wire at the same time, both sets of information are lost because they crash into each other. The bigger the hub based network, the more likely that collisions are going to happen, everything else being equal. When information is lost due to collisions, the two computers have no choice but to resend the lost information, which means that it’s likely to take longer sending a piece of information using a hub rather than a switch.

There we have it, switches take less time to transmit infrmation when compared to a hub, they use less resources, create less network traffic, are more intelligent and far more scalable. So when your boss asks you to look into networking all the PC’s within your company together, you can explain the many reasons why it’s worth spending a little bit more and going with switches.


The Power Of The Computer Network


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The computer network has made significant advances over the last 30 years; no longer is it just an infrastructure for facilitating email and surfing the Internet. The network is now being utilised in such a way that it’s literally saving businesses billions of pounds every year by increasing user productivity and reducing operational costs. Below is a list of common applications businesses use their network for.

Applications

Business has increasingly become reliant on email over the last decade, with a wide range of client / server email applications available to choose from; in the past people used the postal service and telephones to do business, nowadays the number one method of communication is email, according to Gartner.

The power of the database was finally realised when database services became available over the network; countless organisations use bespoke solutions to organise themselves, whether the task be purchasing, administrative, sales, accounting, payroll etc… most are driven by SQL, which in my experience, is still the most robust solution available today.

Attached to a significant percentage of local area networks (LAN) used for business, at least in our experience, are network capable printers, typically laserjet. Despite the talk of paperless offices back in the 90′s, there’s still a very real need for network attached printing services where clients still need to be invoiced and companies still write letters.

Network Storage

Many are the benefits of network attached storage over local storage, or even worse, a paper based filing system. The most obvious to me is the flexibility it provides when accessing the data, you can sort information into logical categories and interpret the information more quickly. The data can be encrypted to ensure it doesn’t fall into the wrong hands, which when compared to a filing cabinet, makes for a much more professional approach to handling sensitive data. Nowadays, the storage solutions available are so good that you don’t have to worry about the drive failing, there are plenty of options such as RAID which guarantee the integrity of your data.

Security

In our experience, the majority of small to medium sized businesses within the UK that use video surveillance equipment are backing up to VHS tapes using cameras with poor image quality, especially in low levels of light. Nowadays, there are surveillance systems that are connected to the network and back up to network storage, sometimes also backing up to offsite network storage. Modern day surveillance cameras are quite adept to recording in low levels of light, such as 0.4 Lux which is a measurement of light similar to very low lit residential street lighting.

Voice

So many businesses we deal with are still using a mainstream telephone carrier and paying far too much for their voice calls. This is madness. With the popularity of SIP trunks on the increase, businesses have an excellent opportunity to streamline their telephone expenditure by placing those calls over their network. A typical organisation will make back the cost of the required hardware within a couple of years where their phone bill will be significantly reduced. The quality of their voice calls aren’t compromised and the features that come with IP phone systems are useful to say the least; voicemail for everyone, hunt groups for sales teams, automated attendants for customers to get through to the right person, even music on hold.

Video

Just as the postal services worldwide have become less about communication and more about the delivery of products purchased online, where email has superseded it, we will also notice a trend moving away from standard voice calls, moving towards video calls. Some of the mobile phone manufacturers are already getting behind video calls in a big way; it’s very likely that in 10 years time video calling will be the standard. All of this is likely to take place over the network as inhouse technical teams lose the fight to keep only data traffic on the network.

Monitoring

The loss to business of people checking their webmail or doing things like reading status updates on Facebook instead of doing their work, is huge. As the lure of social networking sites increases, so will the employers need to monitor their staff. There are already programs that allow your boss to see what you’re doing on your workstation; they may already be watching you waste company time and resources on their new IP video surveillance system. Your slacking days are numbered.


The Importance Of Network Security


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Since the rise in popularity of the Internet, we have started to use our computers for a much wider range of tasks than ever before. At home, we buy our groceries, do our banking, buy birthday presents, send communications via email, write our life story on social networking sites; at work, our businesses provide e-commerce via websites, staff send and recieve emails, phonecalls and video conferencing are done through the network using IP based servcices; all of this is done online and it would present a serious security threat if it wasn’t for the fact we have various security measures at our disposal. I would like to cover some basic examples of how network security helps to keep us safe online, both at home and in the workplace.

Any computer network used for business should employ good network security practices in order to keep free from attacks by hackers. There are a number of ways a hacker can hurt your business:

Denial Of Service
A denial of service attack is used to make your network, or more precisely your website, unavailable to potential users; they do this by flooding the web server with so many requests for information that it uses up all the resources of the web server, which either makes the web server crash, or slow down so much that it can’t handle requests from the websites’ intended users, your customers.

BlackHat Hacking
There are people called hackers with enough technical knowledge to be able to penetrate insecure networks with the intent of doing damage to the devices attached on the network and costing the company as much money as possible. Typical damage would involve changing the configuration of network devices such as servers and routers so that the network becomes unavailable; this can take a long time to fix, which translates to a loss of earnings where productivity is drastically reduced. Even worse, a hacker can gain access to sensitive information such as credit card details or client/patient records, they can even take control of your network based phone system and make expensive long distance calls at your expense. The damage done can cost your company thousands of pounds, if not more, over the space of a weekend alone.

At home, a hacker has less scope to do damage, but if you keep sensitive information on your PC, like credit card details or scanned images of important documents such as passports and driving licenses, it’s clear to see that a hacker can cause you all sorts of grief.

There are a number of technologies and devices that can help keep your network safe:

Firewall
A firewall uses a set of rules to allow or deny access to a network; typically a firewall lives inside of a router. This router is likely to be the peiece of hardware that sits on the edge of your network and provides access to the Internet. The set of rules are based on opening and closing ports relating to protocols; if the network users don’t use a certain protocol, then the router will keep that port closed.

Access Control Lists
An access control list is very much like a firewall; it filters traffic based on a number of metrics contained within an IP packet. The Access Control List (ACL) will be configured to check each packets’ source and destination IP address, also the source and destination port number. The network administrator will write the ACL, specifying which range of IP addresses can talk to which other range of IP addresses and which protocols they can use when communicating. This makes it very hard for a hacker to gain access around a network, where each router is doing its best to block unauthorised access.

Encryption
Encryption is simple; an algorithm is used to turn meaningful information into a format that makes no sense and can only be decrypted by someone with access to the specific algorithm. Whenever sending sensitive information across the internet, it’s advisable to send it using high levels of encryption.

WEP / WPA
Nowadays, everyone has got a wireless network at home, allowing them to access the Internet using their laptop in any room. Protecting your wireless network is a must, otherwise anyone geographically close to you can connect to your network; this is a hackers paradise. Research has shown that WPA and the new version, WPA2, are far more secure than WEP. So when you’re next setting up your wireless home router, make sure your security is set to WPA2.

Simply following the aforementioned advice will stand you in good stead, your computer networks and information will be more secure.