Question

What is a Network Topology?

What are the types of network topologies?

2. What are the types of Ethernet cables?

3. What to use when connecting: a) Switch – switch b) Hub- hub c) Switch – hub d) Switch – end device (e.g. computer)

How to create subnets in a LAN including one switch?

Answer 1

What is a Network Topology?

Network topology is the arrangement of the elements of a communication network. Network topology can be used to define or describe the arrangement of various types of telecommunication networks, including command and control radio networks, industrial fieldbusses and computer networks.

What are the types of network topologies?

a) Mesh Topology :

In mesh topology, every device is connected to another device via particular channel.

                                     

Advantages of this topology :

· It is robust.

· Fault is diagnosed easily. Data is reliable because data is transferred among the devices through dedicated channels or links.

· Provides security and privacy.

Problems with this topology :

· Installation and configuration is difficult.

· Cost of cables are high as bulk wiring is required, hence suitable for less number of devices.

· Cost of maintenance is high.

b) Star Topology :

​ In star topology, all the devices are connected to a single hub through a cable. This hub is the central node and all others nodes are connected to the central node. The hub can be passive ​in nature i.e. not intelligent hub such as broadcasting devices, at the same time the hub can be intelligent known as active ​hubs. Active hubs have repeaters in them.

                         

Figure 2 : A star topology having four systems connected to single point of connection i.e. hub.

Advantages of this topology :

· If N devices are connected to each other in star topology, then the number of cables required to connect them is N. So, it is easy to set up.

· Each device require only 1 port i.e. to connect to the hub.

Problems with this topology :

· If the concentrator (hub) on which the whole topology relies fails, the whole system will crash down.

· Cost of installation is high.

· Performance is based on the single concentrator i.e. hub.

c) Bus Topology :

​ Bus topology is a network type in which every computer and network device is connected to single cable. It transmits the data from one end to another in single direction. No bi-directional feature is in bus topology.

            

Advantages of this topology :

· If N devices are connected to each other in bus topology, then the number of cables required to connect them is 1 ​which is known as backbone cable and N drop lines are required.

· Cost of the cable is less as compared to other topology, but it is used to built small networks.

Problems with this topology :

· If the common cable fails, then the whole system will crash down.

· If the network traffic is heavy, it increases collisions in the network. To avoid this, various protocols are used in MAC layer known as Pure Aloha, Slotted Aloha, CSMA/CD etc.

d) Ring Topology :

​ In this topology, it forms a ring connecting a devices with its exactly two neighbouring devices.

                                

Advantages of this topology :

· The possibility of collision is minimum in this type of topology.

· Cheap to install and expand.

Problems with this topology :

· Troubleshooting is difficult in this topology.

· Addition of stations in between or removal of stations can disturb the whole topology.

e) Hybrid Topology :

​This topology is a collection of two or more topologies which are described above. This is a scalable topology which can be expanded easily. It is reliable one but at the same it is a costly topology.

                                        

What are the types of Ethernet cables?

Types of Ethernet cabling

There are three cable types commonly used for Ethernet cabling: coaxial, twisted pair, and fiber-optic cabling. In today’s LANs, the twisted pair cabling is the most popular type of cabling, but the fiber-optic cabling usage is increasing, especially in high performance networks. Coaxial cabling is generally used for cable Internet access. Let’s expain all three cable types in more detail.

Coaxial cabling

A coaxial cable has an inner conductor that runs down the middle of the cable. The conductor is surrounded by a layer of insulation which is then surrounded by another conducting shield, which makes this type of cabling resistant to outside interference. This type of cabling comes in two types – thinnet and thicknet. Both types have maximum transmission speed of 10 Mbps. Coaxial cabling was previously used in computer networks, but today are largely replaced by twisted-pair cabling (Photo credit: Wikipedia)

Twisted-pair cabling

A twisted-pair cable has four pair of wires. These wires are twisted around each other to reduce crosstalk and outside interference. This type of cabling is common in current LANs.

Twisted-pair cabling can be used for telephone and network cabling. It comes in two versions, UTP (Unshielded Twisted-Pair) and STP (Shielded Twisted-Pair). The difference between these two is that an STP cable has an additional layer of insulation that protects data from outside interferences.

Here you can see how a twisted pair cable looks like (Photo credit: Wikipedia):

A twisted-pair cable uses 8P8C connector, sometimes wrongly referred to as RJ45 connector (Photo credit: Wikipedia).

Fiber-optic cabling

This type of cabling uses optical fibers to transmit data in the form of light signals. The cables have strands of glass surrounded by a cladding material (Photo credit: Wikipedia):

This type of cabling can support greater cable lengths than any other cabling type (up to a couple of miles). The cables are also immune to electromagnetic interference. As you can see, this cabling method has many advantages over other methods but its main drawback is that it is more expensive.

There are two types of fiber-optic cables:

· Single-mode fiber (SMF) – uses only a single ray of light to carry data. Used for larger distances.

· Multi-mode fiber (MMF) – uses multiple rays of light to carry data. Less expensive than SMF.

Four types of connectors are commonly used:

· ST (Straight-tip connector)

· SC (Subscriber connector)

· FC (Fiber Channel)

· LC (Lucent Connector)

What to use when connecting:

a) Switch – switch

If a single switch doesn’t have enough ports for your entire network, you can connect switches together by daisy-chaining them. On older switches, you sometimes had to use special cables (called crossover cables) or designated ports (called uplink ports) to daisy-chain switches together. Modern switches don’t require this extra consideration. Instead, you can daisy-chain two switches simply by connecting any port on the first switch to any port on the second switch.

b) Hub- hub

1) Use a "crossover" cable to connect a "Normal" port on one hub to a "Normal" port on the other.

2) Use a regular UTP (Unshielded Twisted Pair) cable to connect the "Uplink" port on one hub to a "Normal" port on the other.

c) Switch – hub

Two types of cables are used to connect devices to hubs and switches: crossover cables and straight-through cables. The difference between the two types is that in a crossover cable, two of the wires are crossed; in a straight-through cable, all the wires run straight through.

d) Switch – end device (e.g. computer)

A network switch is networking hardware that connects devices on a computer network by ... Each networked device connected to a switch can be identified by its network address, ... In most of these cases, the end-user device contains a router and components that interface to the particular physical broadband technology.

How to create subnets in a LAN including one switch?

Anyone who spent late nights playing video games in their friend’s dorm remembers the joys of setting up a local-area network (LAN) in the days before Wi-Fi. While setting up multiple LANs made for a fun night of gaming with friends, setting up multiple networks on a single router offers a number of vital benefits to today’s businesses and IT professionals.

But given the headaches of deploying and maintaining just a single network on a router, many network admins – or just those managing networks at home – tend to shy away from configuring multiple LANs on a single router.

Before we dive into how to configure multiple networks on a single router, let’s talk about why it can be beneficial.

Why setup Multiple LANs?
While there are many use cases for creating multiple networks, the key benefits are cost savings, security, and access control to specific areas of your network.

While it’s entirely possible that businesses paid to buy and maintain the devices for each separate network, in a small business, this can be accomplished on a single wireless router if that device supports it. For example, many wireless router vendors support a wizard-based configuration for the regular home or small business user. Usually, this is limited to 2 LANs—one for your private network and one for a guest network, for everyone else.

For a large company that needs to deliver Wi-Fi to the entire business, but segment the finance department’s data from marketing while shielding HR data from malicious outsiders, configuring requires an understanding of how networking hardware creates a network and deliver traffic through it. This wouldn’t be configured on a wireless router but on a dedicated router or multi-layer switch.

What do I need to understand?
To accomplish this for a business, you should have a good understanding of Internet Protocol (IP) addresses. This lays the foundation for how the Internet and all of our connected devices interact with each other, giving unique numerical identifiers to everything and everyone on the Internet. Within a private home or office network, every router, switch, modem, and other networking hardware has a set IP address. A single IP address divides into two sections: Network ID and Host ID. The Network ID defines the logical group where devices belong. The remaining section (Host ID) represents the unique device within that grouping. To apply multiple networks, we must understand where the network division happens to create multiple smaller networks.

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When we understand how traffic flows through networks, we can dive into the two main ways to set up multiple LANs on a single router: subnets and virtual local area networks (VLANs).

Subnets
Subnets are the logical groups of addresses that we use to separate networks. A single network can also be subnetted. Subnetting takes a single network and subdivides it into smaller networks. Why would I do it? Let’s say your working with an existing network address block assigned to you. You can use subnetting to re allocate it to be more useful to you by creating smaller networks called “subnets.”

For instance, let’s consider a typical corporate office. You may have been assigned a single address block—1 network with a certain number of hosts per network. But you have Finance, Marketing, and HR departments which have specific needs for security and bandwidth. The router is the networking machine that regulates traffic and sends packets between an internal network and the outside world. It will be configured with an interface for each department – finance, marketing, and HR would each have a subnet. These interfaces will have an IP address on them that will become the default gateway address for each subnet, and the router will route traffic between the subnets and out to the Internet.

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Subnetting networks is a powerful way enterprise IT teams regulate and manage the security needs of each department they serve, but it’s not always the best fit for every network. Virtual local area networks perform similar functions by leveraging hardware resources to segment a network, instead of setting IP masks to segment traffic.

Virtual Local Area Networks (VLANs)
A physical switch is logically equal to a single LAN. VLANs allows us to take a single physical switch and logically group ports into multiple smaller switches. Each smaller group would be a VLAN. This is no the only configuration though. A single VLAN can also span multiple switches to regroup ports from multiple switches to work as a single switch.

For at-home enthusiasts, VLANs cordon off traffic to offer a strong layer of security to protect against intruders attempting to sniff packets on your network. For enterprise network engineers, however, VLANs deliver invaluable improvements in efficiency. IT engineers often have to compartmentalize specific services to different areas of the network; rather than building independent infrastructure for each service, VLANs give the flexibility to construct a virtual network as needed for a vital or load-intensive service without the need for additional hardware.

For enterprise networks, subnets and VLANs are often used in conjunction to work on the network’s different broadcast layers.

VLANs also mean your network isn’t tied to specific hardware. So, if your finance department moves to another office, transitioning their network can be done completely through software instead of migrating an entire network infrastructure.

How to Configure Multiple Networks
Now that we understand the common ways of deploying multiple networks, we can think of the best way to set up multiple LANs by creating a subnet or VLAN on a private network. While this does not typically require any custom software beyond a browser, you’ll often want a physical, wired connection to your router hardware and an understanding of how to manipulate your server software. Let’s walk through a few important terms and steps. For the home user, this will be limited but useful.

Default Gateway Addresses
The default gateway address is an important element in setting your network appropriately. Like it sounds, a default gateway is the intermediary between your local network and the Internet, but also allows the devices on the network to communicate with each other. At home, this is typically your router which accepts an Internet signal from your modem and shares it to the network. You’ll need to know your default gateway IP address to set up subnet masks within your network to segment traffic. In Windows, you can open the Command Prompt and type: ipconfig | findstr /i “Gateway” to learn the default gateway IP.

Logging Into Your Wireless Router
Knowing the default gateway address will let you log into your router and begin to manage subnets or VLANs. Most consumer-based routers have default IP addresses that make it easy to log in. Cisco routers, for instance, typically are 192.168.1.1, with passwords of admin or cisco. You can always do a search with your favorite browser for the default password for your brand and model. If you don’t already have a LAN up and running, you’ll probably need an Ethernet cable to connect your computer to the router.

Setting a Subnet or VLAN
For the home, just walk through the wizard provided to set up an additional VLAN if your router supports it. Just make sure you know your subnet and have chosen the default gateway address to configure.
In a business or enterprise, creating a subnet or virtual network does require knowledge of how the router assigns IP addresses or allocates network resources, some devices will have a web interface but will be more detailed and require more setup. When creating a subnet, you’ll be creating IP addresses that live under the default gateway IP address. For instance, thinking about the Finance department in our earlier example: if the default switch IP address is 176.16.0.0, Finance would be 176.16.10.0/24 while Marketing would be 176.16.20.0/24. Each lives under the gateway IP, but the router knows to send Marketing traffic and Finance appropriately.

As you can imagine, creating a subnet often requires a dedicated IT professional. Selecting the right subnet mask requires calculating how many binary bits your subnet will require to support the devices you need, and then they must be applied within the network infrastructure.

For most people, especially at home, a VLAN will solve most of their issues – like creating a Guest network within your Wi-Fi network or setting up multiple LANs to support things like streaming or multiple game systems on the same network.

To create a VLAN, which often operate within a subnet, you’ll typically find the LAN >> VLAN configuration options within your router. You’ll select the LAN subnet, select which ports on your router should be dedicated to the VLAN, enable VLAN tags and set IDs for each. Once your VLAN is up and running within a subnet, you can set security and access restrictions for the new virtual network running on your single router or network devices. But remember, not every wireless router will support it.