Introducing Wide Area Networks (WANs)

A Wide Area Network (WAN) is generally considered to be a type of computer network that covers a broad area where communications links cross regional, metropolitan or national boundaries. Today, it is probably better to think of a WAN as a network that uses routers and publicly accessible communications links. Without doubt the largest and most well-known WAN is the Internet.

Wide Area Networks (WANs) are used to connect Local Area Networks (LANs) and other types of networks, including Metropolitan Area Networks (MANs), Local Area Networks (LANs), wireless and private networks. The purpose of a WAN is to enable users and computers in one location to communicate with users and computers in other, often very geographically dispersed and separated locations.

Typically a WAN will consist of a number of interconnected switching nodes that allows transmissions from any one device to be routed through these interconnected nodes to the specified destination device(s). These nodes are not concerned with the contents of data rather their interest is focused on the provision of a switching facility to move the data from node-to-node until they arrive at their intended destination.

Wide Area Network (WAN) Models

In essence there are two basic design models upon which all WAN connectivity structures and organization are based. They are:

The Centralized WAN Model - Consists of a server or group of servers in a central location and client computers or dumb terminals that connect to the server(s) which provide the bulk of the network's functionality. Figure 1 above is a logical construct of a typical centralized WAN. Note that all points lead to the centrally located servers.

Today's typical physical Point of Sale (POS) functionality such as that implemented by chain organizations such as banks and supermarkets etc is a classic example of a centralized WAN. Software-as-a-Service (SaaS) and web based applications are other examples of a centralized WAN computing model.

The Distributed WAN Model - Consists of client and server computers distributed throughout the network (see Fig.2 below). The Internet is a distributed WAN.

The three tiered network design hierarchy consisting of a core layer, a distribution layer and an access layer is implemented on top of which ever WAN connectivity and organizational structures are chosen. For more about the three tiered network design hierarchy check this article out Network Design: Hierarchies.

Building Wide Area Networks (WANs)

In order to facilitate the efficient and effective transfer of information between a WAN's end systems a number of protocols (rules that govern the transmission and reception of information between computers and network end-points) needed to be developed and implemented.

Generically speaking; a networking protocol is the formal description of a set of rules that describe, enable, govern and regulate the various characteristics, aspects, attributes and properties of an internetwork. One of the more important early WAN protocols was X.25. Although it is not used today, many of X.25's underlying protocols and functions (with modifications and improvements) are still in use by current iterations of Frame Relay.

Initially, most WANs were built using expensive leased lines. The most common production implementations of leased line based WANs involved the use of a router at each end of the leased line to connect to the LAN on one side to a hub within the WAN on the other.

Wide Area Networks (WANs) Reducing Implementation Costs

If ever the use of Wide Area Networks (WANs), including the Internet was to become widespread and accessible to the bulk of humanity (be it as individuals or collectives) something needed to be done to reduce the startup and running costs of planning, implementing and maintaining WANs. Fortunately solutions did exist.

Less costly alternatives to using expensive leased lines when building a WAN include the use of circuit switching or packet switching technologies. Here, network protocols including TCP/IP serve to deliver transport and addressing functions. While protocols such as Packet over SONET/SDH, Multiprotocol Layer Switching (MPLS), Asynchronous Transfer Mode (ATM) and Frame Relay are commonly used by Internet Service Providers (ISPs) to deliver the links that are used in WANs.

Wide Area Network (WAN) Connectivity Options

Leased Line - Provide secure but comparatively expensive Point-to-Point connectivity between two computers or Local Area Networks (LANs) using protocols such as Point-to-Point Protocol (PPP), High-Level Data Link Control (HDLC) and Synchronous Data Link Control (SDLC).

Circuit Switching - A less expensive dedicated circuit path offering bandwidth data transfer rates ranging from 28K-bit/sec to 144K-bit/sec is created between end points. On the downside call setup and connection establishment needs to be renegotiated every time access is desired because the link is not necessarily permanent. The most well known example of circuit switching WAN connectivity is dial-up connections. Point-to-Point Protocol (PPP) and Integrated Service Digital Network (ISDN) are two of the most widely used protocols for circuit switching WAN connectivity.

Packet Switching - Variable length packets are transported over a shared single point-to-point or point-to-multipoint link across a carrier internetwork using Permanent Virtual Circuits (PVC) or Switched Virtual Circuits (SVC). X.25 and Frame Relayare two examples of packet switching protocols used for WAN connectivity.

Cell Relay - Cell Relay is very similar to packet switching, but uses fixed length cells instead of variable length packets. Data is divided into fixed-length cells and then transported across virtual circuits. Unfortunately the overhead can constitute a significant proportion of the total bandwidth. Cell relay protocols such as Asynchronous Transfer Mode (ATM) (up to 155M-bit/sec) are best for simultaneous use of Voice and data.

Virtual Private Network (VPN) - With the recent reductions in Internet connectivity and concurrent increases in bandwidth and transmission rates now offered by ISPs many organizations have opted to use VPN technologies such as those on offer from the likes of Cisco Systems, New Edge Networks, Juniper, Check Point and Vyatta to interconnect their networks. One of VPN's strong points is encryption and considering the prevalence of cyber-crime today it is no surprise to find that this form of WAN is currently very popular.

Wide Area Network (WAN) Transmission Media and Links

Any given WAN may use one, more or even all of the following technologies for the transmission and transport of information:

Copper-Based Media - Telephone lines, coaxial cable, CAT cable etc

Fiber Optic-Based Cables - Single-Mode and Multi-Mode (see Fiber Optic Cableand Optical Networkingfor more).

Wireless - Radio frequency channels, microwave links, satellite channels and publically accessible wireless “hot spots”

Wide Area Network (WAN) Transmission Rates

Typically, WAN transmission rates usually have ranged from 1.2K-bits/sec to 6 M-bit/sec, although some connections such as ATM and Leased lines can reach speeds greater than 156 M-bit/sec. The advent of ADSL 2+ has upped the ante even further.

Now with transmission rates up to 30 Mbps, DSL and cable modem are two high data-transmission rate consumer Internet connections that transmit considerably faster than a dial-up modem (56 kbps). Add to this the fact that they are also generally cheaper than both ISDN and dial-up and you get a very cost-effective solution.

Wide Area Network (WAN) Access

Wide Area Networks (WANs) may be public (usually built by Internet Service Providers (ISPs) to provide Internet connectivity) while others are private (built for a specific organization). That is to say that public access to an organization's “private” network component is regulated by that organization. In contrast, access to public networks and user privileges remains largely unregulated beyond the criteria as defined by the agreement between the consumer and your Internet Service Provider (ISP).

Hence, the general public, anonymous and guest visitors, colleagues, business partners, and associates etcetera may be permitted limited privilege access to various sectors of an organization's private network but not to all of it. Functionalities, services, assets and user capabilities will vary greatly on a case-by-case network-by-network basis.

Demilitarized Zones (DMZs)

A classic example of this regulated limited access is commonly implemented in the form of Demilitarized Zones (DMZs) that allow public access to a very restricted and confined portion of an organization's private network. Here they may be able to access a web server for e-commerce, technical support or even just for casual browsing. You cannot make a sale if you cannot communicate with your customers. Even auto responders and automated shopping carts require some degree of two-way participation from both the customer and your software.

Metropolitan Area Network (MAN)

Another increasingly more common type of WAN is the Metropolitan Area Network (MAN) which is basically the same as a WAN except that its boundaries are contained within a single metropolitan area (city).

In Australia, a MAN can be viewed as a network for which standard landline telephone communications are charged at the local call rate (not STD) as all endpoints have the same area code. With broadband configured as a permanently connected service the customer only pays the local call fee for the initial setup connection or reconnection if the service is interrupted for any reason.

Examples of private Metropolitan Area Networks (MANs) would be the corporate links between various branches of the same organization (chain stores, banks) in the Perth metropolitan area. The key here is that regardless of the protocols or other technologies being used, part of the transit will be via publically accessible networks such as the Internet. The remainder will of course be contained within the boundaries of their “private LAN”.

WANs, MANs and Interoperability

Internetworking and interoperability are key factors critical to the realization of effective and readily available e-commerce portals as well as other external network resources and services. Regulatory and other compliance issues also need to be taken into consideration.

The seamless, secure interoperability of multiple systems and networks is essential in order for the general public to have free and ready access to those components of the enterprise LAN/MAN/WAN deemed desirable by that organization/enterprise.

For example; it is usually deemed to be highly desirable that the general public have rapid seamless access and interactivity with an organization's e-commerce facilities such as the shopping cart, support services if appropriate and resources such as online documentation.

The expansion of Web 2.0 functionality and the upsurge of social networking applications all rely heavily on the effective and efficient seamless integration of internetworking and interoperability technologies at all levels.

Hierarchies

For the most part the large scale plans that we humans find easiest to comprehend and thus implement tend to be based and structured around a hierarchal model. So, rather than using a “flat network” model upon which to base our design we will use the far more plastic hierarchal model as it allows us a far greater degree of granular control and subdivision of roles and functionalities of its constituent components.

We are now going to take a quick look into the key principles of three-tiered hierarchal network design model that allow the network's which we design to scale as and when required whilst still providing the means by which we can retain control over its functionalities, performance, accessibility, maintenance and evolution with as little effort as possible.

As the name indicates the three-tier network model is a dramatic departure from the flat network philosophy of the past. Fundamentally; this is a layered approach, where the three layers into which all devices are classified are; the core layer, the distribution layer and the access layer. More than 90% of all network elements including infrastructure components like transmission media will fall neatly into one or other of these three categories.

I say more than 90% because there will be those special components which may straddle layer functionalities or perform multiple roles. The modern ADSL broadband modem router with a built-in multi-port Ethernet switch is a common example of this type of device. So do not be fooled into thinking that a three-tiered model ordains that there must be separate devices for each layer.

The number of devices (routers, switches etc) will be in large dictated by the situation specific requirements and resources of each internetwork being designed on a per internetwork basis. What might be considered to be appropriate for a particular internetwork design solution may be totally unreasonable for another.

Always remember that it is the internetwork designer's capacity to incorporate appropriate levels of plasticity and redundancy into their design solutions that is the art in forging an internetwork design that will work and perform in accordance with the desires and capabilities of those commissioning the internetwork. Budgetary concerns will, as is nearly always the case, be one of the biggest driving forces at work here.

The Core Layer

At the top of the hierarchy the core layer is literally the core of the network. A network's core layer's purpose & responsibility is squarely focused upon the transportation of large amounts of traffic both reliably and quickly.

This means that the core should switch traffic as fast and reliably as possible because any failures at the core level will most likely affect every single user of the network. User data should be processed by the distribution layer which will forward it to the core layer if appropriate. When designing a network the high priority objectives that should be built into the core layer include:

High speed, highly-reliable fault tolerant components possessing the lowest possible latency characteristics connected in such a manner as to eliminate bottlenecks are all high priority factors greatly desirable of a networks core layer. Therefore, the routing protocols implemented at the network's core layer must be those with the lowest convergence times as any delays will be amplified downstream throughout the network and hence felt by all.

The core layer's data-link technologies must exhibit high speed with built-in redundancy such as FDDI, Gigabit Ethernet or 10G Ethernet incorporating redundant links and even SONET or ATM both of which also include multiple redundant links.

Ideally there should be no access lists, access list processing or packet filtering performed by the core layer. This means that there will be no workgroup access or workgroup access support provided by the core. Nor will any inter-VLAN routing take place here.

One final point of advice is that one should upgrade to increase core performance rather than expand (adding routers etc.) as the internetwork grows.

The Distribution Layer

The distribution layer (also referred to as the workgroup layer) is the communication point between the core layer and the access layer. The distribution layer should not duplicate the roles or functionalities provided by any of the other layers. Your design solutions should therefore reflect this by ensuring that the distribution layer is characterized by the deliberate exclusion of all factors, services and functions that are or should be the providence another layer.

Furthermore, other design concepts that need to be at the forefront of one's thought processes when designing a network are that the primary functions of the distribution layer will encompass many intermediary or “middle-man” network aspects, functionalities and services. These functions must be transparent to the user.

Network functionalities implemented at the distribution layer will include many of the network's core infrastructure-based decision making processes including routing, routing protocol redistribution, static routing, inter-VLAN routing, best path determination and address translation. Ideally, the definition of broadcast and multicast domains, packet filtering, queuing and the implementation of access lists should all occur at the distribution layer.

Network policy implementation and network security implementation occurs at the distribution layer and includes both hardware and software devices and solutions. Since WAN access provision is generally implemented at the distribution layer firewalls (Cisco PIX, Microsoft ISA server, Zone Alarm etc.), intrusion detection systems and intrusion prevention systems and appliances are incorporated into the network at the distribution layer.

Other critical decision making functions of the network that get implemented at the distribution layer involve core layer access determination (the how & when packets can access the core) and core layer access restriction (limiting access to the core layer on an only if absolutely necessary basis).

The determination of the manner and mechanisms for handling network service requests is conducted by distribution layer devices. For example determination of the fastest way for requests to be forwarded to servers and other peripheral Services (e.g. Internet Access).

Workgroup support functions, the implementation of additional tools and the provisioning of network operation flexibility are some more tasks generally assigned to the distribution layer.

The Access Layer

This brings us to the access layer which is also referred to as the “desktop” layer. The main functions of the access layer revolve around access control, regulation of users and workgroup access to the network/internetwork's assets, resources and services.

The pervading philosophy of “shortest distance” should prevail when designing an internetwork's access layer. This means that those resources that the majority of a group of users or workgroups access regularly should be available locally. Here is where the 80/20 rule comes into play.

The 80/20 rule states that 80% of all network traffic should remain within the boundaries of the local segment. Even better is to subnet a Local Area Network (LAN) and so contain the “local” traffic to a single broadcast domain and only 20% of all network traffic will be transported via the core layer throughout the entire internetwork. This does translate to “real world” performance gains for all concerned.

With the distribution layer taking care of any requests for remote resources & services the access layer's functions, resources and services should focus primarily upon such criteria as workgroup connectivity to the distribution layer and the elimination of potential avenues of direct unabated user or workgroup access to the core layer.

Access layer traffic containment and resources access strategies often include additional network segmentation through the creation of separate collision domains (e.g. by using transparent bridging workgroup class switches or LAN Switches) and more specific access controls & policies to further augment those implemented by the distribution layer.

Static routing protocols rather than dynamic routing protocols should be used at the access layer. DDR Ethernet switching is another technology commonly used at the access layer. Local resources at the access level will include local printers, workstations, caching servers and workgroup switches the use transparent bridging.

Temporary and mobile devices (laptops, notebooks, PDAs, smart phones etc.) must not be permitted any direct access to the core or distribution layers. Rather they should connect via the access layer in a highly secure manner.

This is most often implemented via demilitarized zones (DMZs) as one can never be sure what nasties the device may have picked up on its wanderings. Generally the device will be scanned immediately upon connection and cannot be used for network access until after it passes its sanitization requirements. Better safe than sorry.

DMZs are also widely employed to allow Internet traffic a web site while reducing the web site/web site's owner potential exposure to malware. Email, bulletin boards and interactive Web 2.0 sites are other situations where implementation of DMZs is commonly used to erect a “barrier” between the public and private domains while allowing users (including the anonymous variety) to maintain their full site experience without unduly exposing the site to every piece of malware or bad intent out there.

Messiah offers real-time playback speed, which is a blessing to any animator. Without having to waste time on previews, animators can work quickly and efficiently to produce a higher quality of work in a shorter time.

Messiah supplies a no-nonsense user interface that is easy to navigate and customize, allowing the user to feel more comfortable within the 3D environment. A pleasant surprise is how many settings the user is allowed to change to suit their personal workflow.

Messiah 3.0 does not have it's own modeling tools, but allows you to import a model from a variety of 3D modeling programs, including Lightwave 5.x or 6.x objects (.lwo), Wavefront objects (.obj), 3DS (.3ds), BioVision Mocap Data (.bvh), DXF objects (.dxf), Messiah Motion (.fxm), Messiah Scene (.fxs), Motion Analysis Hierarchical Translation Rotation (.htr).

Once the model is imported the user can create an animation rig. You point and click to create the bone, and Messiah uses its own initiative and skins the bone for you. Creating an armature for a character can often be a frustrating, time-consuming affair, but with Messiah, the process is easy. Copying an armature from one character to another is easy, and requires only a small amount of time to adjust the rig to fit the new character.

Animating with a fully rigged character in Messiah is as easy as spreading butter on bread. Nothing holds you back and you can truly lose yourself in the joy of breathing life and personality into the character. Changing between the timeline and the dope sheet is a simple click away, and for someone like me who uses a pose to pose method to create the initial animation, easy access to the dope sheet is a must.

Editing and deleting keys is a quick, easy process, and Messiah offers a variety of on-screen tools and sliders that are great for facial deformations and phonemes.

The compose tab allows the user to create clips for the character, which are easy to insert anywhere on the timeline. This is especially useful and time-saving for adding walk sequences into a shot.

To render, one must bake out the character motion and then load the character in the software that they wish to render in. The Messiah plug-in then deforms the vertices of the character frame-by-frame. This process is a bit frustrating at first, but again, Messiah does all the hard work, which allows you to concentrate on other aspects of the production.

On the whole, PMG's Messiah 3.0 is a powerful piece of software, focusing specifically on the needs of character animators and rigging artists. It is affordable, straight-forward and offers plenty of long awaited animation tools. PMG's innovations with this software have caused a lot of excitement in the animation industry and I look forward to enjoying future upgrades of this software.

The Star Topology Network

With a Star Topology network, each node (Servers, Workstations, and Peripherals) connects directly to a centrally located Hub / Concentrator (seeFigure ST 1).

Data always travels from the transmitting node through the hub or concentrator before continuing to its destination.

Network Management

It is the job of the hub or concentrator to manage and control all functions of the network. The central hub/concentrator also behaves like a repeater for the data flow in that it reshapes the signal before passing it on.

Switches do a similar job as well. Having discussed hubs, concentrators, switches and repeaters in earlier articles, I will not dwell on them here.

Star Topology Supported Transmission Media

One of the greatest assets of the star topology is that it can use practically any type of available transmission media. For copper-based wired networks, some flavor of twisted pair cable (usually UTP) is the most common type of transmission media generally found in star topology networks.

Copper-Based Transmission Media

Unshielded Twisted Pair (UTP) is the most abundant variety of copper cable available today. Therefore, it should come as no great surprise to discover that Unshielded Twisted Pair (UTP) cabling is in deed the predominant type of transmission medium (cable) found in the star topology networks of today.

This holds true for most of the other topologies to boot. Volume production has meant that UTP cable is considerably cheaper than its competitors are. Advances in UTP cable capabilities over the years have seen the continual evolution of UTP cabling to the point where it is today.

Star topology networks built around Shielded Twisted Pair (STP) and coaxial cable are still in active service today. They are disappearing quite rapidly however as existing networks upgrade to higher performing infrastructures. These “new” network infrastructures tend to be a mix of wireless and wired technologies.

The Wired Component

For the wired component Unshielded Twisted Pair (UTP) CAT5/CAT6 or above dominate. The use of fiber-optic cable in star topology networks is generally limited to those situations demanding “extreme” performance, immunity from Electro-Magnetic Interference (EMI), long cable runs and other scenarios where UTP is unsuitable.

Fiscal Considerations

One should never lose sight of the fact that above all else the greatest advantage that copper-based transmission media (wires/cables) has over its rivals is cost. Copper cable is considerably cheaper than fiber-optic cable.

Star Topology Protocols

Protocols commonly associated with a star topology include Ethernet and LocalTalk (Apple's Proprietary Protocol). Both protocols, Ethernet and LocalTalk require a different NIC

Star Topology Ad Hoc Networks

The star topology also lends itself for use in ad hoc networking scenarios and hence is very popular with small business and home networks. In fact, this sector constitutes over 60% of all networks. The driving impetus here has been the desire to save money by sharing an Internet connection between numerous machines.

Star topology is very popular with peer-to-peer network scenarios. The ease with which nodes come and go is one of the biggest reasons that the star topology is so popular with peer-to-peer networks. LAN parties and gaming sessions are a breeze. For these types of ad hoc network use, the star topology model is most definitely the easiest to install and configure.

Plug "N" Play Connectivity

Most ADSL, broadband modems on the market today include an integrated 4-port, switch capable of transparent bridging. The average consumer and small business alike find themselves ideally placed to use these types of “plug "n" play” network and Internet connectivity devices.

Star-Wired Ring Topology

A star-wired ring topology such as that implemented in IBM's Token Ring networks appears very similar to the classical star topology externally (physically). Both have nodes that connect to a central hub/concentrator or switch. The nodes themselves only differ in terms of the Network Interface Card (NIC) used.

• In order to connect machines to an Ethernet network an Ethernet NIC is required
• On the other hand, to connect to a Token Ring network a Token Ring NIC is required

Multi-Station Access Unit (MSAU)

All member devices of a network that uses a star-wired ring topology must connect to a special type of device called a Multi-Station Access Unit (MSAU). Externally the MSAU appears to be very much like a normal hub, switch or LAN Switch.

Internally at the hardware level however, the Multi-Station Access Unit (MSAU) contains wiring which allows information to pass from one device to another in a logical circle or ring.

IBM's Token Ring protocol uses a star-wired ring topology. The Token Ring Multi-Station Access Unit (MSAU) is the heart of the Token Ring universe.

Star Topology Advantages

Cable Selection - The star topology permits the use of UTP, STP, coaxial and fiber-optic cabling. This allows for greater diversity and flexibility at setup time. The star topology is backwards compatible with the older cable types so long as the central hub/switch supports it.

Cable Installation - Cabling is straightforward and easy to install particularly when UTP CAT5 or above is used.

Connectivity - With devices, connecting directly to the central hub/switch greater freedom of configuration is possible. Moving a PC to somewhere else in the room or even to another star topology room is simple and speedy.

Reduced Outages - Network disruption and downtime is greatly reduced when connecting or removing devices. Generally, there is no need to power down any device other than the device slated for removal.

Peer-to-Peer - Simplified ad hoc Peer-to-Peer (P2P) networking schemata

Troubleshooting - Easier to use & more streamlined troubleshooting courtesy of the ability to isolate problem devices made possible by the star topology's physical connectivity simplicity

Upgrading - Component replacement, upgrading, the installation of service packs, hot fixes, patches and the addition of new features is a lot easier with a star topology than linear bus and physical ring topologies

LAN Switches - Implementation of a star topology in conjunction with LAN Switches, gives us the ability to fragment collision domains. This offers great improvements in network performance over bus and ring topologies

Routers and Virtual Local Area Networks (VLAN) - Adding routers and Virtual Local Area Networks (VLAN) will also improve network performance as well as providing for greater security control over resource allocation and access.

Star Topology Disadvantages

More Cable - More cable is required to implement a star topology than would be the case for a linear bus topology

Single Point of Failure - If the central hub or switch dies then the entire network will be unable to communicate with each other & externals networks

More Expensive - Hubs & switches are not free and additional cable adds to initial outlay costs to the implementation of the star topology in comparison to the linear bus topology

Network Operating System (NOS) Images

As I have been having trouble sending, the graphics with these articles I have decided to include said graphics for the entire series in a separate photo gallery entitled “Network Operating System (NOS) Images”.

I will also keep on trying to send them embedded into each article. Once the upgrade to the lines in our area is complete, things should be better.

Next time in “Network Operating System Ring and Tree Topologies”, we will look into the Ring and Tree Topologies including their implementation indicators. Until then enjoy!

The centralized, distributed and distributed central network operating system models rate a mention here from a topology perspective as well. However, let us start with the peer-to-peer and client/server network operating system models and the gambit of possible topologies that they potentially encompass.

Network Operating System (NOS) Topology

To keep things simple we will initially look at computer networks from the fundamentalist perspective where we will assume that all network operating systems and network operating system models are able to implement the following topologies, in some form or another.

Two Categories of Network Topology

The two categories of network topology that we are going to discuss are:

1. The Network Physical Topology

   This refers to the configuration of cables, computers, and other peripherals

2. The Network Logical Topology

   This describes the method used to pass the information between workstations

Network Operating System Network (NOS) Topology Types

Just as there are different, categories of NOS topologies so to there are different types of network operating system topologies. These topologies apply equally to networking, communications, client/server networks, converged Unified Communications (UC) networks and to a lesser degree to the peer-to-peer network.

Here are some of the topologies that we will be discussing: Direct Link Topology, Linear Bus Topology, Ring Topology, Star Topology, Mesh Topology, Tree Topology, Hybrid Topology, Hierarchal Network Topology, Centralized Computing Topology, Distributed Computing Topology, and Distributed Centralized Hybrid Computing Topology

Direct Link Topology

The direct link networking topology is without doubt the simplest of all. It is very easy to setup (install, implement, configure and maintain).

The basic minimal requirements necessary for the successful implement of a production environment network based around the direct link network topology are as minimal as it gets.

The entire setup depends on every machine to be connected having the appropriate number of Network Interface Cards (NIC) installed. With this taken care of the only, other requirement is a special type of network cable known as a crossover cable.

Details about making your own crossover cable are located in the Networking and Communications section. I will update this article with the correct link immediately upon publication of this article. You also have the option of purchasing a crossover cable. They are relatively inexpensive in today's market place.

Direct Link Networking Implementation

Simply connect both ends to the devices (computers, printers etc) that you wish to network.

Ensure that both machines are members of the same subnet. Then either create a new shared folder or share an existing one. Configure the appropriate permissions and security descriptors. You will need to perform this procedure on both machines. Add the content that you wish to share and you are up and running.

Ad hoc peer-to-peer network scenarios are the most common implementations of the direct link network topology. It is easy to setup but becomes impracticable when more than three devices are to be connected primarily due to the extra costs of having to purchase a Network Interface Card (NIC) for every machine you want to connect with.

• Suppose you want to network three computers then each computer will need two network interface cards (one NIC for each connection)
• Now consider the scenario where you want to connect four computers. Each machine will still require one NIC for each machine to which it wishes to connect. This means that each machine will need at least three NICs giving us 12 NICs all up.
• Five networked machines using the Direct Link Network Topology will require 20 NICs (Four per machine). I do not think I need to go any further as the impracticality of this system increases exponentially as the number of devices to be networked increases.
• The name given to this type of network topology is “physical mesh” topology

Exclusive Dedicated Links

In its simplest form a Direct Link Network Topology is comprised of exclusively dedicated links. Each member of each pair can use their own networking components of the Direct Link Network; cable, NIC etc to communicate directly and exclusively with its associated pair peer, to the exclusion of all other nodes.

Today we find that the main implementation scenario using a Direct Link Network Topology is with networks containing small numbers of devices. This includes the peer-to-peer network operating system.

More recent implementations of the Direct Link Topology involves external devices such as print devices, scanners, Multi-Function Centers (MFC), USB flash drives and other more robust external drives based upon the “normal” array of Hard Disk Drives (HDD).

Having introduced network operating system topologies and look into the Direct Link Topology we are now ready to move on to discussing more network operating system topologies such as the Linear Bus Topology, Ring Topologies and Star Topologies. This is where “Network Operating System Linear Bus Topology” takes up the story. Until then enjoy!

Network Operating System Models

To keep things simple we will look at computer networks from the fundamentalist perspective where we can say that there are two models for networks:

The Peer-To-Peer Network Model

In the Peer-To-Peer network operating system, model (see Fig. NOS-1), all nodes are equal. There is no hierarchy and there are no dedicated “servers”.

All of the computers must have Network Interface Cards (NIC) and other network connectivity infrastructure such as cables, hubs and switches just like in the client/server network operating system model. Both the peer-to-peer and the client/server network operating system models use the same cabling, NIC, hubs, switches etc.

Every node/computer on a peer-to-peer network must handle network security and administration for themselves. Yes, this does mean that you will need to perform exactly the same task multiple times, once for each machine. Automation is not the peer-to-peer network operating system model's strong point.

Every user must make the decisions about who gets access to what individually on a machine-to-machine basis (remember no automated administration).

The Client/Server Network Model

With the Client/Server Network Operating System Model a new device known as a server, joins the network. Another difference here is that for most implementations of the client/server network operating system all nodes will need to access the server before resources including internet connectivity become available to them.

In Figure NOS-3 above you can see that logically speaking for the Client/Sever Network Operating System model all roads lead to the server. This is the most basic fundamental difference between the peer-to-peer and client/server network operating system models.

Network Operating System Model Differences

As already stated the biggest difference between the peer-to-peer and the client/server network operating system models is the SERVER. All roads lead to the server (in the logical sense). The server performs the security and administrative duties for the entire network.

Another major difference between the two types of network operating systems is the manner in which the network is constructed. Peer-to-peer networks tend to be ad hoc in the manner of their construction. That is machines join the peer-to-peer network more or less randomly, they will come and go and generally the other machines really could not care less.

The client/server network operating system model is the opposite. Structure usually in some form of hierarchy is the order of the day here. Machines are “aware” of the presence or absence of network members. This become very important when we introduce a special type of server called a domain controller or a name server into the mix.

The manner in which both network operating system models arrange their members is another difference and this is where we will take up the story in “Network Operating System Topologies”. Until then enjoy!

I assume you have read my past tutorials and know where the tools that I have mentioned in the previous tutorials are located

Well, why don't we get started? Fire up AutoCAD and start up a new drawing. I'm going to start with the most complex pieces of the model, first off is the handles on the draws of the desk.

Well, create a circle anywhere in the drawing with a radius of, let's say 10:

If you don't have the object snap toolbar on, turn it on now. This toolbar is very important. You can turn it on by right clicking the space above the AutoCAD drawing, going to ACAD and clicking on Object Snap:

Once that's sorted, select the line tool which is underneath the Line tool by clicking on it OR by typing “_line”.

Then on the object snap toolbar which you should be able too see since you activated it, click on “Snap to Quadrant” which is the circle with the 4 smaller circles around it:

Now click on a quadrant on the circle (preferably the one I have clicked in the picture below):

Once you have clicked there, go back to the object snap toolbar and click on “Snap to Quadrant” again. If you make a mistake and click the wrong one, press ESCAPE and start over from creating the first line.

Move your mouse down and click on the quadrant below the previous quadrant as shown in the picture below:

Create another 2D circle with a radius of 9 using the centre of the last circle as a snap:

Now activate the press pull tool, click on the inside of the outer circle but outside of the inner circle and to the left of the 2D line (see picture below). Then for the height input 1.5 and press ENTER:

Good, now we have our desk handle. Delete all of the 2D lines and circles, we don't need them anymore. Adjust your view so it's similar to mine in the picture below:

Create a 3D box using the top right corner of the handle as a snap, for the length input 25 and press TAB to input width. For the width input 5 and press ENTER:

The height can be whatever, but just make sure it goes DOWN:

Activate the 3D rotate tool. Select the handle itself and press ENTER. For the base point, use the same corner as you did for the starting point of the rectangle. Pick the blue rotational axis. Then lastly for the angle point, click on the same spot as the base point.

Now the handle should be rotating with your mouse. This time holding shift isn't going to work so we are going to rotate the handle the hard way. Zoom in and get a closer view. Adjust your view so it is comfortable and easy to work with.

Now take your time and move your mouse until the other end of the handle touches the box and seems align with it. This part can take a long time but don't rush this. Once you are satisfied, click to finalize it. See the picture below if you are unsure where to place it:

Once it is aligned, delete the 3D box as we don't need it anymore. The handle though we DO need so don't delete that.

Adjust your view so you can see the inner curve of the handle and create two 2D lines crossing as shown in the picture. This will give us an intersection snap to work with:

Activate the copy tool located under erase tool by clicking on it OR by typing “_copy”. Select the two 2D lines plus the handle itself and press ENTER.

For the base point, it doesn't matter at all; just click anywhere close to the handle.

Now there should be another handle that is moving with your mouse. Just place it close to the original handle, doesn't matter as we are going to move it again later:

Create a 3D box relatively close to one of the handles with the dimensions as shown in the picture below:

Remember this step's location; you are going to come back and repeat these steps. Select the 2D line tool and click on the "Snap to midpoint" snap located in the snap toolbar:

Then click on the left side of the rectangle midpoint, a red triangle should appear in that place:

Once you have clicked there, activate the "Snap to midpoint" snap again, and click on the other side of the 3D rectangle's midpoint. You should end up with a line looking like this:

Then draw a 2D line from the above left corner down to the midpoint:

We are going to draw another 2D line, but first activate the "Snap to midpoint" snap. Click in the middle of the newly drawn 2D line:

Then activate the "Snap to perpendicular" snap as circled in the picture below:

Then go to the other side of the rectangle and click at the 90 degree sign as shown in the picture below:

You should end up with another line like this:

Then find the centre of that by drawing 2 lines intersecting each other from the corners of the 2 lines going across the rectangle. I have done this a lot in my tutorials and the picture below shows what you should have:

Great, remember how I told you to remember a certain step's location? Well we are going to repeat from that step to the one before this step, but this time on another 3D rectangle with dimensions as shown below:

Once done, you should have something that looks like this now:

Now it's time to join the handles up with these rectangles. Adjust your view until you can see your handle's X formed by the 2 lines.

Then select the 3D move tool, select a handle (doesn't matter which one, but make sure you only select ONE handle), press ENTER and set the base point as the intersection of the 2 2D lines of the handle.

Now your handle should be moving with your mouse, adjust your view so you can see the intersection of the lines of the first 3D rectangle that you drew earlier.

Then click at the intersection:

And now your first rectangle should look like this:

Do the same and join up the second handle with the second rectangle. You should have something like this now:

Now select the fillet tool. Input "t" and press ENTER and press ENTER again for TRIM:

On the first rectangle (the bigger one) select the bottom edge:

Even though the entire object was highlighted, only the edge will be selected. For the fillet radius, input 3 and press ENTER.

Now select the 4 edges on the rectangle that surround the handle (be careful that you don't select the 2D lines that we drew before):

Then press ENTER to execute the tool. Now your rectangle is nicely rounded off:

Fillet the other rectangle exactly how I showed you just now.

Now you should be left with this:

Moving on, activate the 3D move tool; select both the handle and the panel of the smaller desk draw.

Now for the base point specify one of the lower corners of the panel, but that corner cannot be a filleted corner:

The smaller panel + handle should be moving with your mouse. For the next point click on top corner of the bigger panel. That corner cannot be filleted as well. It also must be on the same side of your smaller panel's base point (if you chose the bottom left corner, you would choose the top left corner of the bigger panel, don't worry it will snap into place):

Now you should have something like this:

Adjust your view so you are facing the back if the panels if you aren't:

Select the 3D box tool once again, click on the top right hand corner (the one in the picture below):

Input the width of the rectangle as 50 and the length 100 then press ENTER:

For the depth, click on the bottom left corner (the un-filleted one) and it will adjust itself:

Now we have something like this (I've adjusted the view):

Create another 3D box using the top left corner of the desk:

Make the width 105 and the length 150:

For the height, specify 10 and press ENTER

Currently we should have this (don't mind the 2D lines):

Next, use the bottom right corner of the newly created rectangle as a snap and create a 3D box that is 105 wide and 10 long:

For the height, just use the bottom corner of the rectangle (NOT the filleted one) and click there. It will adjust itself to it's level:

We should have this so far:

We are almost there, adjust the view so you see the back of the desk:

I'm going to create a panel for the back. The length will be 90 because 150 - 10 - 50 = 90. For the width input 5 and press ENTER. Use the top right corner of where the 2 rectangles touch:

For the height input 35 and press ENTER.

Now you should have something like this:

Ok, pull out the fillet tool and trim the edges pointed out in the picture below with a radius of 3 like we did with the panels (NOTE: You cannot fillet them all in one go):

Once you filleted all these edges, fillet these ones as well:

Now we should have something that looks like this:

Well, I guess there is one thing left to do, open the materials panel by right clicking at the top of the tools palette and selecting “materials”

Here is my desk:

This is the second project in my AutoCAD tutorial series. This time we will be making something more simple using new time-saving tools.

We are going to make a soft-drink cup with a rounded lid (so it doesn't look too plain). The cup will consist of 3 parts, the cup base, the lid and lastly, the straw. Here are some rough dimensions I quickly drew in paint:

With that in mind, let's get started. I'm going to start on the base of the cup. Open up AutoCAD and using the 2D circle tool, click and create a circle anywhere in the AutoCAD drawing window and input 5 for the radius (since radius is half the size of diameter) and press ENTER:

Now select the 2D line tool and click at the centre of the newly created circle to start off a line:

Now it gets a bit tricky. For the height, input 12.5 but DO NOT press enter or click:

Now press the TAB key to adjust the angle of the line. Now look closely, HOLD down SHIFT and move the mouse so that the line appears to be standing up. NOTE: Look for the +Z, if you can see it you know you got it right. When you are happy finalize it by clicking:

Now you have a line going up from the centre of the circle. This line will be used as a drawing aid. (Press ESCAPE to stop the 2D line tool if you already haven't). Now select the 2D circle tool again, this time clicking at the end of the 2D line you just created (the snaps should automatically highlight the end in red):

For the radius of the circle, input 6.5 and press ENTER:

So far you should have something that looks like this:

Select the LOFT tool by clicking on it at the 3D make panel OR by typing “_loft” and pressing ENTER:

This tool in short, creates surfaces between 2 or more cross sections; it's sort of a “filler” tool. Anyways with the loft tool selected, first click on the base of the cup (the bottom 2D circle) and then click on the top of the cup (the top 2D circle):

Press ENTER and you will see this:

Press ENTER again and a settings window will appear. Make sure “Ruled” is selected and press OK:

Now we have our cup base:

With that done, we are going to make the cup lid. Now move away from the cup by using the pan tool (don't move away too far, we just need some space to work with). Now select the 2D circle tool again and draw a circle with a radius of 7 and press ENTER:

We are going to draw another vertical 2D line, so select the 2D line and click at the centre of the circle:

This time, for the length of the line, input 4:

Press TAB, hold shift and move the mouse until the line looks upright and you can see the “+Z” then click to finalize your line:

Press ESCAPE to de-activate the line tool. Activate the 2D circle tool and draw a circle on top of the line we just created, for the radius, input 5 and press ENTER:

Now, activate the loft tool again. Click the 2 2D circles we just created:

Now press ENTER and then select “Cross-sections only”:

Now the loft settings screen will once again come up. Change the settings to match the picture below:

Press OK and you should have something similar to this:

Activate the cylinder tool. Move your mouse to the endpoint of the 2D line we created before we lofted the circles and click there:

For the radius, input 4 and press ENTER:

For the height go down, we want the cylinder to pass through the lofted object because we are going to subtract that. The height doesn't matter, as long as it passes through the lofted object:

Activate the subtraction tool. First select the lofted object FIRST and press ENTER. Then select the cylinder we just made and press ENTER. You should be left with this:

Great! That's the second piece done, time for the last. Move away from the cup lid to give ourselves some room to work with. Activate the Polyline tool by clicking on it OR by typing “_pline”:

Firstly, click anywhere (not too far away from the cup lid) to create a starting point. For the second point, input 20 and press TAB and for the angle, input 90. Press ENTER:

Like the 2D line tool, we can continue and draw another line. For the length of the next line, input 5 and press TAB and for the angle, input 60 (since 180 - 60 = 120), once done, press ENTER:

Then press ESCAPE to stop using the tool. Unlike the 2D line tool, the 2 lines we created are joined together. Next activate the 2D circle tool and draw a circle next to the line we just created with a radius of 0.5 and press ENTER:

Create another 2D circle and click at the centre of the circle we just created:

For the radius, input 0.3 and press ENTER:

You should have something similar to this:

Moving on, activate the sweep tool by clicking on it OR by typing “_sweep”:

Now while the sweep tool is active, select BOTH circles we just made and press ENTER:

For the sweep path, select the line we made earlier (the Polyline):

Now you should have something like this:

Change your view using the constraint orbit tool so you can see the end of the straw (either end, doesn't matter):

Select the subtraction tool, firstly select the outer round object as the source and press ENTER. Then select the inner object and press ENTER and you should have something like this:

Great! We have something that resembles a straw! All we need to do now is to put the pieces together and “colour it in”. Firstly let's deal with the cup lid. Adjust your view so you can see the cup lid:

Select the 3D move tool and select the cup lid with it and press ENTER:

Now the 2D line you created at the cup lid should be still there. Move the mouse cursor to the bottom of the 2D line's endpoint and click:

Now the cup lid should be moving with your mouse. Move your mouse so that it goes over the cup base and place it over the cup base's 2D line's endpoint and click:

Now we have something that looks like this (yes, the lid is meant to be bigger than the cup base, otherwise how can you put it on?):

All the cup is missing is a straw. Adjust your view so you can see your straw again:

Zoom in at the bottom end of the straw (the side without the bent end) you may need to use the pan tool to adjust your view:

Select the 3D rotate tool and click on the straw then press ENTER:

For the base point, click at the centre of the circle shaped end of the straw:

Then select the red axis (the one that is highlighted in yellow in the picture below):

For the angle starting point, click at the same spot as the base point (should have a snap):

Now the straw is freely moving! Hold SHIFT and move your mouse until the straw is standing upright, then click:

Just a few more steps to go, adjust your view so you can see the bottom part of the straw clearly:

Select the 3D move tool, and select the straw and press ENTER:

For the basepoint, select the centre of the straw end (or endpoint, if the 2D line is there):

Now the straw is freely moving. Here's a tip if you haven't already figured it out. While using other tools, you can use the view tools and change your views. Once you finished changing the views, press ESCAPE to stop the tool and resume using the previous tool.

Anyways, back on task move the straw and click at the centre point/ endpoint of the cup base using the tip I showed you above if needed:

So far, here's your cup:

Do you know what's wrong with it? The straw is standing upright. We are going to fix this. Select the 3D rotate tool and select the straw and press ENTER:

Now zoom in until you can see the outline of the highlighted straw clearly. For the basepoint, select the centre of the straw end OR, if the 2D line is still there from the first few step, use that:

For the rotational axis, select the green axis (the one highlighted in yellow in the picture below):

For the angle starting point, make it the same as the base point:

Now the straw is rotating with your mouse. Now move your mouse so that the straw appears to be touching the side of the cup lid. You may need to adjust your view to get a better look. Once you are satisfied, click to finalize it:

Anyways, once done select the explode tool by clicking on it OR by typing “_explode”:

This tool will break down an object. Once you selected it, select the cup base ONLY and press ENTER:

Now the cup base is now 3 different objects. Why did I explode it? Now that the cup base is in 3 parts, I can colour each part separately, the top part of the cup base could be coloured as the liquid that the cup contains so I don't have to draw another object and the other 2 parts could be the colour of the cup itself. Confused? Well in a moment I'll show you my cup and it will become clear.

Open the materials panel by right clicking at the top of the tools palette and selecting “materials”

Here you can “colour in” your cup with the different materials available. I'm not going to hold your hand and tell you which materials to select, you should decide that yourself. Anyways, here is my cup in render mode (I have never been good with colouring in):

For example I have a model that looks like this (this is just an example, nothing too flash):

Here I have set up 4 viewports, one monitoring each corner of the model. By doing so, when I want to work on another part of the model I don't have to keep adjusting my view to see, I already have a viewport monitoring that area. Of course, you can edit the model in any of the viewports making it very convenient. The only downside of multiple viewports is that the ports are smaller than having just one ort (of course):

Now let's see how we can enable multiple viewports. Click on View > Viewports. Here you have the option of selecting multiple viewports from 1 - 4. If you select 2 or 3 viewports, AutoCAD will prompt you to select an alignment option. For example if you selected 2 viewports, AutoCAD will ask you if you want them horizontal or vertical. Once you made your choice, AutoCAD will create the viewports according to your choice:

Right now, I have chosen to have 4 viewports:

Each viewports currently is identical. In order to edit a viewport, you must select it by clicking it. You can tell which one is selected by the highlighted outline of the viewport. Here I have created a box in the top left viewport:

As you can see, all 4 ports have the same box. Here I have adjusted the views of each viewport to face a different corner of the box by using the constraint orbit tool as you would normally:

Now here I have created a sphere on one of the corners of the box:

As you can see, each viewport displays the sphere in its own perspective. Another neat thing is that you can zoom in with viewports:

Another feature of viewports: You can split a viewport into more viewports. To do so, simply select the viewport you want to be split and create more viewports as I showed you above:

Each of these smaller viewports could be used for displaying certain features of that particular area. You can further split these smaller viewports into even smaller viewports. You can have a LOT of viewports, here I have 32 viewports. That is 32 views of a single model:

Here are the main points if you were too bored to read through my tutorial. Sorry if this tutorial seems a bit vague and hard to understand:

• Viewports are mainly useful for LARGE and VERY detailed drawings where you would be very time consuming to keep adjusting views to edit the model.
• You can have more than 4 viewports.
• You can only make changes to the model in the viewport that is currently active.
• You can adjust the view in each viewport.
• More viewports result in smaller viewports.
• To create viewports, go to View > Viewports.
• To join 2 viewports and create one, go to View > Viewports > Join. Then you select the 2 viewports you want to join.
• You can only join viewports that are beside each other and not diagonal.
• For a small and simple model, it would be best to use just one viewport.

Firstly select the “Frustum Cone” tool from the modelling tab at the tool palette:

This tool is a little shortcut for making a cone with a flat top. Now click anywhere on the drawing and input 10 for the base radius and press ENTER:

And for the top radius, input 4 and press ENTER:

Lastly, for the height input 20 and press ENTER:

This is what we should have so far, a nice cone with a flat top:

Next select the cone tool in the 3D make control panel:

Move your mouse towards the center of the first cone that we just finished making and using the center snap (which should be activated automatically) click at the center of the first cone's top:

For the base radius of this cone that we are creating, enter in for and press ENTER:

And the height, we will make it 14. So input 14 and press ENTER:

This is what we should have so far:

Let's move aside that for a moment and create another part of the pencil. There are 3 parts to this model, the pencil tip, body and the end. Once we create all 3 we will then put them together.

Moving on, select the polygon tool in the draw tab at the tool palette:

For the number of sides, input 6 and press ENTER:

Now click anywhere to the right of the pencil tip and select “Inscribed in circle” when the options come up:

For the radius of the circle in the polygon, enter in 10 and press ENTER:

Now select the press pull tool or type in “_presspull” and click inside of the 2D hexagon we just made:

Now enter in 100 for the height and press ENTER:

This is what we should have so far:

Now it's time to create the last piece of the model. Select the cylinder tool and to the right of the hexagon we previously made click and input 10 for the base radius and press ENTER:

For the height, input 20 and press ENTER:

Now we have an end, all we need to do is create the rubber on the end. Select the cylinder tool again and look for the center snap on top of the cylinder we just created and click on it:

For the base radius, input 9 and press ENTER:

For the height, input 10 and press ENTER:

Select the fillet tool from the modify tab at the tool palette:

Now input “t” for trim and press ENTER:

Select “Trim” if it isn't already selected and press ENTER:

Now select the edge of the last cylinder we just created:

For the fillet radius input 3 and press ENTER:

Press enter again since it asks for an edge and we already selected one:

Now we have a nice rounded off cylinder:

Now that we have all 3 pieces of our model, we are going to do some assembling. First though draw 2 lines which join 2 points that are opposite each other on top of the hexagon tower so that they intersect, forming a middle point:

Back to the pencil tip, activate the 3D move tool and select both cones of the pencil tip and press ENTER:

Adjust the view using the constrained orbit so that you can see the bottom of the pencil tip. Then move your mouse so it snaps with the center snap of the bottom cone and click:

Now the pencil tip should be moving with your mouse now. While it is, use the pan and constraint orbit tool to adjust your view again to view the top of the hexagon tower. When you have finished adjusting your view, press ESCAPE on the keyboard. Doing so stops your current action and since you are still using the 3D move tool, you resume using it again. Now click at the intersection point where the 2 lines on the hexagon tower cross.

Now it should look like this:

As you can see, the pencil tip is bigger than the hexagon tower. We will fix that with the slice tool. Now activate the slice tool (you may need to click on the double arrow to expand the 3d make section to see it):

This tool lets us slice objects. Firstly specify the object we are going to slice by clicking on it and pressing ENTER, in this case it is the lower cone of the pencil tip:

Now click at one of the points on the hexagon tower to be like a starting point:

For the second point, click on a point next to the first point we selected. This will tell us which direction the slicing tool is going to cut:

When you slice an object you are left with 2 pieces, the object itself that has been cut and the cut piece. We can choose to keep both if we wanted to but in this case we only want to keep the object itself. Pretend there is an imaginary line where we cut it; the picture below it is the red line I have drawn. If we click on the side where the object itself is, then we will keep the object and discard the cut. If we click on the other side of the line then we will discard the object and keep the cut. We want the object so click above the imaginary line (you won't see that red line in AutoCAD) to keep the object itself:

Currently it should look like this now:

A hexagon has 6 sides. We have already done one side. Using the constrained orbit tool to adjust your view, slice each side as I showed you before. It should look something like this now:

Back to the hexagon tower, adjust your view you can see the bottom of it. While you are there, draw some 2D lines to create an intersection point at the bottom of the hexagon tower to use as a snap (be sure the lines go to opposite ends of the hexagon):

Time to put the other end onto the pencil, re-adjust your view so you can see the last pencil object we made (the other with the chamfered end) then activate the 3D rotate tool, select both cylinders of the pencil end and press ENTER:

Move your mouse and let the cursor snap to the center of the bottom cylinder end and click (You may need to move your mouse around to get the snap to appear):

For the rotational axis, click on the one highlighted in orange in the picture below:

For the angle starting point, once again click at the center, letting it snap (you may need to move the mouse around to make the snap appear):

Now hold SHIFT and mouse the mouse around until the pencil end is facing downwards like the one in the picture and click:

Now activate the 3D move tool and select both cylinders of the pencil end and press ENTER:

Now move your mouse and let it snap to the top of the bigger cylinder center using snaps then click:

Now the pencil end should be moving with your mouse. Using the constrained orbit tool to adjust your view, adjust it so you can see the bottom of the hexagon tower and press ESCAPE to resume using the 3D move tool then click at the intersection where the two 2D lines we drew earlier intersect. (They may be hidden from view by the pencil end that is moving around with your mouse but still search for it by moving your mouse around):

Now we finished putting the parts together. It's starting to look like a pencil:

Let's lay it facedown using the 3D rotate tool. Activate it and select all 5 pieces of the model and press ENTER (there should be 5 pieces excluding the 2D lines):

Zoom in at the bottom of the hexagon tower and click on the intersection point we previously used or the center of the pencil lid (doesn't matter):

For the rotational axis, select the one highlighted orange in the picture below:

For the angle starting point, click at the intersection point at the bottom of the hexagon tower or the center point of the pencil lid (doesn't matter):

Hold shift and move your mouse until the model is lying down and then click:

Open the materials panel by right clicking at the top of the tools palette and selecting “materials”

Now, using this panel you can “colour in” your pencil, giving it texture and fill etc. You can experiment, and see what will go together good etc. This is my pencil in render mode:

Well, I've hoped you enjoyed this tutorial as much as I have when writing it.