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Technology Explained: How Does a Router Work?

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Technology Explained: How Does a Router Work?

Oct. 10th, 2009 By Guy McDowell

routerLately, the Technology Explained articles have talked about the Internet and communications in general. This article will add to that series by explaining a very important piece of equipment – the router.

In order for a computer to connect to more than one other computer, you need a router or a hub. Two very different pieces of equipment that perform somewhat similar jobs. We’ll focus on the router since you very well may have one in your house.

Let me take a moment to explain to the more technically inclined that I understand that there are such things as token ring networks that don’t require a router or a hub. Yet, our average Internet user isn’t going to employ a token ring, so leave that alone, please.

Many of you will have wireless routers, a few of you may have wired routers. How the information gets to and from the router isn’t that important to this discussion. What is important is how does a router work – what happens inside the router with all that data coursing through it. To keep it simple, I’m going to use a 3 computer network to explain the routing principles.

So, let’s say you have three computers in your home and a connection to the Internet. This will give us a network that looks like such:

how does a router work

In the middle of that, is the wireless router. I know you knew that, but it had to be said. Wirelessly attached to it are a laptop, a PC, and a Mac (just for you Jackson!). Actually, the Mac is in there to show that the computers don’t necessarily need to be the same kind or platform. One might be sending up a file to work, one might be downloading something from YouTube and one is reading MakeUseOf.com – of course. All this information is coming down from, and up to, the Internet.

Believe it or not, the router can only talk to one of these things at a time! The process I’m about to talk about just happens so fast that it seems to happen all at once.

Let’s say that the Mac is uploading a file to work, the laptop is watching YouTube and the PC is surfing MakeUseOf.com.

Each communication happens in small packets of data. You might recall this from the How the Internet Works article I did awhile back. The IP address in that article was the important thing that allowed packets to find their way to your computer. Here’s a packet:

how does a router work

The important parts, for this article, are the Source Address and the Destination Address. These will be Internet Protocol (IP) addresses.

However, if you are using a router, your computer’s IP address is going to begin with either 198.168.0 or 10.0.0. This is because the powers-that-be decided that those IP address would be reserved for local network use. Like in a home network.

Here’s the catch. There are millions of local networks out there. So, at any point in time, there are millions of people using an IP address exactly like the one your computer is using on your home network. Your router will have to keep track of that AND tag the outgoing packets with the true IP address that your Internet Service Provider has given to your modem.  I’ll call that the external IP address. How does the router do that? That’s the question.

I am going to oversimplify this, not to speak down, but to keep this article a reasonable length. The router takes your computer’s local IP address out of the packet’s Source Address and puts it in a table. It then puts the external IP into the packets Source Address space. The router also copies the Destination Address IP from the packet and puts it in the table associated with your local IP. Confuzzled? Me too. I really had to think about how to say this in everyday speak and not geek-speak. Here’s a picture:

how does a router work

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how does a wireless router work

When the packet comes back from that server somewhere out on the Internet, the Destination Address IP is now your external IP and the Source Address IP is now the IP address of the server sending you a packet. (Note: that is the IP address of Telus.com – not my home IP address.)

Think of it like a letter. You send a friend a letter and the return address is yours, and the send-to address is theirs. They write a letter back and the return address is theirs and the send-to address is yours. See how that works? We should write more letters.

how does a wireless router work

Well, the router looks at the Source Address IP of the incoming packet and looks it up in the table as a former Destination Address IP. When it finds it, the router says, “Aha! Guy’s computer sent a packet to that IP address. His computer must be waiting for a reply! Here’s Guy’s local IP address so I’ll pull out the external IP address, pop his local IP address in and send it on its way!” That’ll do router, that’ll do.

how does a wireless router work

You can imagine, with how many thousands of packets travel in and out of your home every minute, how fast this sorting process has to be! It happens so fast, you never even notice the fact that at one moment the router is talking to the Mac, then the laptop, then maybe the Mac again, and then the PC. Miracles everywhere – just stop and notice.

I hope you enjoyed this article on how a router works, and now have a better appreciation of what’s going on in that silly box of electronics next to your modem. If there are any other technologies you’d like me, or our other great writers, to break down for you, I’d be glad to hear about it in the comments!

Image Credit: A.Mohsen Alhendi

(By) Guy likes words and occasionally forms complete sentences. He can count to potato. Check out his USB shilling at USBDriven.com.Follow MakeUseOf on Twitter!

All good useful stuff!

Posted via web from Ffynnonweb Foibles

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What is SWWHEP exactly?

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The South West Wales Higher Education Partnership (SWWHEP) is a flagship collaboration project in Welsh Higher Education. Three higher education institutions (HEIs) in the South West Wales region are currently working closely together in an innovative partnership to integrate and enhance a range of services to students and staff.

£7.5 million has been awarded by the Higher Education Funding Council for Wales (HEFCW) to Swansea University, Swansea Metropolitan University and Trinity University College to implement change in key administrative services under the SWWHEP Reconfiguration and Collaboration project.

The project is the first of its kind in the Welsh higher education sector. Funding was approved by the Welsh Assembly Government under its “Reaching Higher” agenda to support HEIs in Wales in their attempts to improve performance, enhance competitiveness, and improve value-for-money in public services.

The eLearning strand of the SWWHEP project – under whose auspices I am currently employed -aims to establish an eLearning Centre of Excellence for all partner institutions which will build upon the support centre that has already been established at Swansea University in the Library and Information Services Section. The focus is to work very closely with the academic staff in all participating Institutions to develop and embed eLearning into the curriculum and culture of all partner institutions. As a result of initial planning involving all current partners and a consultant from Blackboard, (the company who provide and licence the commercial online virtual learning platform used by the partnership) the project has evolved into three distinct phases as documented below:

1. Setting up and implementation of the Blackboard Academic Suite v8 and subsequent upgrading to Blackboard Learn Release 9 during the academic year 2009/2010 – this has a rather more web 2.0 flavour and should prove to be even more appealing and user-friendly to staff and students alike. This will facilitate easier collaborative working across the institutions at an academic level. On the administrative side it will centralise the technical management, and enable the establishment of shared training and support for Blackboard including the establishment of an online knowledge base to provide greater support at points of need.

2. Development of the Blackboard installations to take full advantage of new features in the Learning, Community and Content Systems. These three interlinked parts of the Academic suite will enable each institution to deliver services through Blackboard which better reflect the needs of learners. The three components are powerful and complex and there will be a rolling programme of working groups to develop the most effective solutions. Many of these groups will be cross institutional to share experience and expertise and will comprise academics, students and administrative staff facilitated by eLearning Support staff.

3. Establishment and development of a virtual eLearning resource centre (centre of excellence). Work on establishing this began early in the academic year 08/09 alongside the development of Blackboard. The exact nature, operational structure and name of the centre has yet to be agreed by the partners but its overall aim will be to provide a shared eLearning resource and Community of Practice across the partner institutions. Essentially it will be a virtual centre supported by the project staff across participating institutions. The remit will be to facilitate eLearning in its broadest sense and to help each institution embed eLearning into their local framework and culture.

A consultation and training exercise is currently underway across all three partner institutions and the eLearning Team is working with staff in each institution to build out a prototype of the new Blackboard Community Portal which will enrich and enhance the student online learning experience across all campuses. it is hoped to go live with these portal systems by September 2009.

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Case Study: Moving to Web 2.0: Part 1: The Community

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This is the first part of a three part series of articles detailing a case study that I undertook recently as part of a research project into social media and online communication.
Please also read:

to gain the full picture…

When I was deciding upon a suitable topic for my dissertation, (extracts from which can be read in the previous posts on this blog) I decided that a rewarding area of research would be to investigate the social side of the web and to attempt to prove my theory that social communication online mirrors social communication offline and has done so from the very early days of online communities right up to the latest revolution in online social networks. That the internet has in effect come full circle with the new emphasis on people, user generated content and social communication but that online communities have remained the same, it is merely the platforms they operate in that have changed.

Online Communities may be defined as follows:

  • Communities of Purpose – members are trying to achieve a similar objective.
  • Communities of Circumstance – generally more personally focused.
  • Communities of Interest – united by a common theme or interest but whose members may know very little about each other outside this shared interest.
  • Communities of Users – beginning to be developed by some of the more innovative business networks to engage with their customers in a more informal, interactive way than had hitherto been the case.
  • Communities of Practice – perhaps the most well-known and researched in academic circles – these are communities of people who are engaged in the same profession, vocation or ‘practice’ – they facilitate professional exchanges which may also add value to offline networks.

The initial motivation for undertaking this particular project was the desire to move a splinter group of an existing online community of interest from a Web 1.0 forum to a newly created online social network. The decision to move to a social network on the new Web 2.0 platform rather than another Web 1.0 forum, was made because it was instinctively felt that the members of the current forum who were principally interested in the social science of observation and analysis of behavioural patterns, albeit through the 24/7 observation of the housemates in the television show Big Brother via the TV or Internet Live Feed, would also be interested in and embrace the enhanced social aspects of the Web 2.0 software. It was expected that change management issues would be of great significance at all stages of the move and it was decided that this would be a rewarding subject for in-depth study.

The Case Study.

The story ostensibly began in the summer of 2007 with the launch of the reality TV program Big Brother 8 UK, but had its roots back in 2003 when I first joined a Big Brother forum on a large public website.

Initially, I contented myself with what has been described as ‘Legitimate Peripheral Participation’ (Lave and Wenger)1 which, in the world of online communities, is more colloquially termed ‘lurking’.

I watched the programs on the TV, subscribed to the 24/7 Internet Live Feed from the Big Brother House and read the threads in the forums where members discussed and analysed the housemates’ actions and behaviour. After a little while, I felt sufficiently confident and knowledgeable to begin to join in these discussions and moved from a ‘lurker’ to a ‘newbie’ – literally a new poster in the forums. Over the years, I increased my level of participation through every series of BB, until I had become something of an expert on the subject and had raised myself to the level of ‘practitioner’ in the community where I was able to help and guide other, newer members of the forums and became a ‘Key Contributor’.

The diagram below that was designed for the Lurker Project, illustrates the three types of people who may be found in an online community.

When I was not absorbed in Big Brother, I was developing a keen interest in the Internet and the web and set about increasing my knowledge by creating, designing and developing websites, whilst also becoming fairly proficient in the creation of web graphics. This interest in web graphics led me to open my own graphics website and I began to write tutorials and build up a large collection of resources on the subject. Gradually, the resources and the tutorials broadened their scope to include more general topics related to web development and the Internet in general. In this way, I became particularly fascinated by the new Web 2.0 social media that was beginning to make its appearance on the internet and had already begun to dabble in some of these areas by the summer of 2007 when Big Brother 8 was launched.

Many members of the BB forums were absorbed by the turbulent relationship of two of the housemates in that season – Chanelle Hayes and Ziggy Lichman (nicknamed ‘Chiggy’ by Big Brother) and a number of us began posting regularly in the ‘Chiggy’ thread throughout the summer and autumn as we continued to follow their media activities outside of the BB House. In the ‘post-Chiggy’ era (after the relationship between the two housemates had ended acrimoniously with a ‘Kiss and Tell’ story in the Sunday newspapers by Ziggy Lichman), followers of the relationship split into two camps. This led to a war of words ensuing in the BB forums (dubbed the ‘Chiggy Wars’) and in an attempt to restore harmony to the general BB forums, moderators eventually forcibly split the two groups into separate Appreciation Threads, where supporters could converse and share information. Those members who had supported both parties continued posting in the joint appreciation thread – the Chiggy thread mentioned above. Unfortunately however, this thread was continuously ‘invaded’ by supporters of each individual housemate and was eventually closed.

The small nucleus of remaining ‘Chiggy’ supporters thus found themselves metaphorically ‘homeless’ and I started a new ‘refugee’ thread in a general forum to allow us to chat quietly amongst ourselves, away from the warring factions. After a short time though, we were ‘discovered’ and the previous discordant atmosphere was replicated in the ‘refugee’ thread. The moderators had no choice but to close this thread as well and we were advised against creating any more similar threads for obvious reasons.

At this point one of our group members contacted us all via private message to tell us that a new private forum away from the public website had been created for us to use. Membership of the forum was by invitation only and this was to be limited to our small ‘Chiggy’ refugee group.

However, it very quickly became apparent that invitations were being passed on to virtually everyone who had ever posted in the Big Brother forums about either housemate.
Naturally, this soon resulted in the disharmony that had been such a problem in the BB forums being transferred to the new private forum. There were some major differences however, because the public forums are very heavily and anonymously moderated with miscreants being summarily banned from the forums, either temporarily or permanently.

The new private forum consisted of several different boards catering for a variety of entertainment interests as well as just ‘Chiggy’. Individual boards for both halves of ‘Chiggy’ were created to ensure that members would not squabble amongst themselves as had been the case in the public BB forum. Unfortunately, the ‘one size fits all’ mentality of only posting in one single ‘on-topic’ thread on one board that the group had become accustomed to on the public BB forum remained ingrained into the psyche of most members of the new forum and they all clustered into the one Z&C joint thread and refused to move out.

The idea of posting in the one thread would have been perfectly fine if membership had been restricted as originally envisaged. The fact that a more diverse group of people had joined caused problems from the outset. I likened it at the time to a large family wedding when a number of family members who do not really get on with each other are herded together into a crowded room and forced to co-exist. One is fortunate if several fights have not broken out by the end of the evening!

Anarchy was threatening to take over due to this ‘family wedding’ atmosphere, so I offered to help out. I had operated several similar forums on my own websites in the past and thought that I could easily take some of the pressure off by running the administration control panel and undertaking some moderating duties in the forum. What I failed to realise and this only became clear to me much later on, was that my general approach to the group as a whole was completely at odds with that of the founding members and that my offer of assistance was only accepted out of desperation. With the benefit of hindsight, my intervention, far from being the cavalry turning up to save the day as I had rather naively and optimistically hoped, merely placed a sticking plaster on a deep wound that actually required major surgery to allow the healing process to take place.

The group that formed over the shared bonding experience of following the fortunes of ‘Chiggy’ was a somewhat idiosyncratic, extremely diverse collection of people although the majority of members were females between the ages of 35 and 65. Many of these people were highly opinionated and became incredibly passionate in their devotion to and defence of one or other of these housemates. Perhaps because two of the housemates remained in the public eye for longer than is normally the case, the supporters group also stayed together longer, and deeper friendships were formed.

This goes some way to explain why so many of us moved across to this forum and why so many of the members continued to squabble and attempt to settle old scores when they got there. They had been restricted from doing so in the public BB forum under the threat of a lifetime posting ban – the management style there was very authoritarian, with members being treated in a similar manner as employees on a production line having no say whatsoever in the process. Threads were summarily closed, posts removed and entire chunks of conversation deleted if they became contentious. Forum moderation is anonymous and autocratic with little or no right of appeal.

On reflection, I can now see that most people moved to the new forum with a sense of release and a feeling that they would be afforded ‘freedom of expression’ as one member succinctly put it, without the draconian moderation of the public forums. They did not want to be moderated, organised and controlled and revelled in the new freedoms. However, with freedom comes responsibility and I think it was widely expected that people would use these new freedoms sensibly and responsibly, without any real need for management or supervision. Unfortunately, some members took full advantage of this relaxed atmosphere and this was when anarchy began to take over. I set about attempting to impose some rules and regulations and this had the sticking plaster effect as described above, for a short time.

Meanwhile, some people continued to flout the terms and conditions on DS to the point where they were banned for life from posting in the public forums. A few members got round this by creating new online personas, but others did not and were forced to decamp permanently to the new private forum.

One fascinating fact about online personas is that they are often (but not always) quite different from the person’s real offline personality. It has been observed that extrovert personality types are less comfortable in an online persona than introverts, perhaps because they need to be seen and heard and are used to being the centre of attention. Introverts by contrast, find it easier to hide behind a computer screen and develop a much more aggressive, lively or passionate persona online than the one that they exhibit in the real world. I can only conclude that this must be the case with some members of the Z&C group, because if they exhibited the same aggression and combativeness offline as they did online, they would all either be high-powered CEOs running multi-national companies or part of a criminal underworld! The fact that most have ordinary jobs and families and are probably nice, mild-mannered folk generally, lends a certain credence to the above argument about on and offline personas.

As the atmosphere in the forum worsened, my role amounted to little more than a daily routine of fire-fighting with no back-up. Finally, things became so bad that I decided that it was ridiculous to spend all my free time doing something that was supposed to be enjoyable, but had become unpleasant and was making me unhappy. It slowly dawned on me that I was being over-worked, under-valued and used for my technical ability, but that I was not really wanted in the role I was performing. I knew then that it was time for me to leave, but had got so used to spending all my time with some people that I had grown quite fond of, that I wondered if there was some way that this friendship could be continued in surroundings that were more conducive to fun and enjoyment.

This is when I had the idea that I might be able to combine leisure and research in the form of a new online social network.

See also Part 2: The Online Social Network for details of the move and Part 3: Aftermath and Conclusions.

1 Lave, J. and Wenger, E. (1991) Situated Learning: Legitimate Peripheral Participation. Cambridge: University of Cambridge Press.

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