Lets Network

When you connect 2 or more computers together, you are creating a LAN (Local Area Network).

When you connect a computer to the Internet, you are joining a WAN (Wide Area Network)!

Connecting to other computers.

If you are only connecting 2 computers to share information, this is called a Peer to Peer network and you can do this using one  Ethernet “crossover” cable or you can use a Hub or Switch and 2 cables (no need for crossover cables). An alternative is to use WiFi and in some cases you can use Bluetooth but Bluetooth isn’t very fast and doesn’t really have the capacity of WiFi.

When you are connecting more than 2 computers, you will need to use a hub or a switch (a switch is an Intelligent hub)  🙂

With either method you need to manually assign an IP Address* for each device on the same network.

However, If you use the router supplied by your ISP (to create a LAN), it will normally include a 4 port switch and will have a DHCP server capability built-in, along with NAT. It will automatically assign an IP Address to each device connected so you won’t need to manually assign one. It should also config the SNM and Default gateway.

You can normally connect up to 4 computers to the ISP Router when using Ethernet cables (or more using a separate switch)  but using WiFi, you can connect (in theory) up to 250! 2 or more computers connected are called a LAN (Local Area Network). It is local because it is local to you and completely separate from the Internet. The LAN is “Private” and the Internet WAN is “Public”. The ISP Router makes this separation by using a basic Firewall called NAT, the router does a lot more but you can read more about NAT and Firewalls on the Security – firewall menu.

Basically, when you power up a “network device”; it sends an electronic message (broadcast) to all devices on the network to ask “who am i”. If you have a DHCP server, it will send a response of something like “you are 192.168.2.20” and that (assigned) IP address will be unique for that network, in this case the “20” will represent the host address.

*IP address. An IP address is a unique identity, much like your postal address. Each “network device” on any network needs a unique address / identity. The current IPv4 addresses use a dotted quad notation using 32 bits (using 4 groups of 8 bits) to give a unique “identity” for each device on the network. This 32 bit identity is in the form of xxx.xxx.xxx.xxx. e.g. 192.168.124.253, 172.16.2.20 etc.The octets are numbers between 1 & 254 (0 & 255 are not normally used). The complete IP address is made up of the “Network address” and the “Host address“. A “Subnet Mask” is used to identify the network address from the host address  In many cases the “subnet mask” uses 24 bits (shown as 255.255.255.0) so the first 3 octets are the “Network address”  e.g. 192.168.124.x and 172.16.2.x. the last octet is the “host address” e.g. xxx.xxx.xxx.253 and xxx.xxx.xxx.20.

An IP Address of 192.168.1.10 that uses a 24 bit SNM would (in effect) become 255.255.255.10 to give the “host” IP address.

Here’s a good site to have a play with a subnet calculator, have fun 🙂

IPv6 IP addresses use 128 bits in the hexadecimal format, this has become necessary because we are “running out” of IPv4 addresses. The use of NAT and “sub netting / Super netting” have delayed the need to change from IPv4 but IPv6 will become the defacto standard in the next few years. Microsoft and others already use IPv4 and IPv6 concurrently, to aid the switch over. You can use the “ping” command in Windows and it defaults to IPv6 address unless you specify IPv4.

Google for IPv6 if you want to know more 🙂

Have a play.

Open a “command prompt” (as admin) and enter ping loopback, then click return/enter.

You should get a result like this:-

Pinging test01 [::1] with 32 bytes of data:
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms
Reply from ::1: time<1ms

Ping statistics for ::1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

test01 is the netbios name of your PC (it will be different to yours)

Now enter ping -a test01 then click return/enter.

You should get a result like:-

Pinging test01 [fe80::2ca9:871f:5fe2:aedf%16] with 32 bytes of data:
Reply from fe80::2ca9:871f:5fe2:aedf%16: time<1ms
Reply from fe80::2ca9:871f:5fe2:aedf%16: time<1ms
Reply from fe80::2ca9:871f:5fe2:aedf%16: time<1ms
Reply from fe80::2ca9:871f:5fe2:aedf%16: time<1ms

Ping statistics for fe80::2ca9:871f:5fe2:aedf%16:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

The number starting with fe80…(in this case) is the IPv6 IP Address.

Now enter ping -4 -a test01 then click return/enter.

you should get a result like:-

Pinging test01 [192.168.0.104] with 32 bytes of data:
Reply from 192.168.0.104: bytes=32 time<1ms TTL=128
Reply from 192.168.0.104: bytes=32 time<1ms TTL=128
Reply from 192.168.0.104: bytes=32 time<1ms TTL=128
Reply from 192.168.0.104: bytes=32 time<1ms TTL=128

Ping statistics for 192.168.0.104:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms

The number starting with 192.168.. is the IPv4 IP Address.

Maybe try ipconfig /all then enter/return.

This will give you all you need to need to know about your network config.

It will show the assigned IP Address both IPv6 & IPv4.

Use the “ping loopback” as the “go to first” to help trouble shoot any network issues, followed by “ipconfig /all” .

NOTE. The “Physical address” is also known as the “MAC address”.

To see all the options of using IPCONFIG just enter ipconfig /? (+enter/return).

Useful info on ipconfig from Microsoft.

Some other useful Windows commands from How to Geek.

Creating a LAN using a switch (intelligent hub) is easy ish. You just need a switch with enough ports for the number of devices you want to network and you will need Ethernet cables to connect between the switch and the network device / PC. Modern PCs and laptops have a built-in NIC (Network Interface Card) and will have an Ethernet port to insert the Ethernet cable.

Instead of using a switch and Ethernet cables, you could use WiFi. You would need a “Wireless Access point” (WAP) which is basically a switch but all done using radio signals. Modern PCs and laptops have a built-in WNIC (Wireless Network Interface Card) as do phones and tablets.

The above will give a “self-contained” LAN with no access to the Internet but you will be able to share files and printers.

To get Internet access, you will need to connect the switch or WAP to your ISP provided router.

For most households Using the ISP router is the simplest way to create a LAN that has Internet access, if it has built-in 4 port switch and / or WAP ! It will usually have a DHCP server built-in so this simplifies things even more. The router will have a LAN IP Address, usually 192.168.0.1 or similar so any device connected to it (using Ethernet or WiFi) will automatically be assigned an IP Address similar to 192.168.0.10, the difference will be the last octet (if using a 24 bit SNM). You can set the DHCP server to allocate IPs in a certain range e.g. you can decide that the most devices that will be connected to your LAN will be say 30 devices and you can start the “allocated” IPs at say 192.168.0.10. Your router will be say 192.168.0.1 and any devices attached will be assigned an IP of 192.168.0.10, 192.168.0.11, etc.

The IP address is important as is the the SNM (subnet mask). You will also need to know the “Default Gateway”, which is the IP address of the router (provided by your ISP). Most (ISP provided) home routers have NAT and DHCP (server) built-in. The NAT bit allows you to have a “private / non routable IP Address” and the DHCP bit automatically allocates unique IP addresses to network devices on your LAN. The (private / non routable) IP address of your router it is often 192.168.0.1 or 192.168.0.254 (the 3rd & 4th octet can be any number between 0 & 255)

When setting up the DHCP server, you just need to make sure the (LAN) IP of the router is correct along with the SNM and the default gateway. If you don’t enter the default gateway, you probably won’t be able to access the Internet.

NOTE. if you want to access the Internet, the “Default Gateway” should always be your ISP provided router (Internet gateway). If you are using your Internet Gateway to create a LAN (WiFi or Ethernet), the default gateway should be the same IP as the LAN / Internal IP of your Internet gateway.

Your ISP is allocated “blocks” of  “public” IP Addresses and they use sub / super netting to dynamically assign your router with an “external” IP Address, this is done by modifying the SNM (sub net mask). You can check your external IP address by visiting ipchicken but remember that your network device will have an “Internal” IP Address which will usually be 192.168.x.x and this is achieved by the use of NAT. The IP address shown by “ipchicken” will be the external (public) IP address.

Network devices actually communicate at the MAC address level, which is another unique identity. This is “hard wired” (by the manufacturer) into the NIC (Network Interface Card) but we won’t go there 🙂

It is useful to be aware of the MAC address, if you are accessing the router “logs” to see what devices are connected to the router. In most cases it will show the MAC address of the device(s), along with it’s “assigned” IP address.

The MAC address never changes but the IP address can and often does, unless you assign “static IP addresses”.

The “NetBios name” is something that can be changed e.g. Windows might create a “human friendly” netbios name for the device and this can be something very random or you could give it a name like “fred” / “betty” / “any name you want”. You can change this any time you like and the “assigned” IP address can change but the MAC address never changes.

Simple Internet connection

At one time, the only way to achieve connecting 2 or more computers together was by using an “Ethernet” cable. For the past 20+ years this cable has consisted of 4 pairs of wires and this is still the most reliable method of connecting (networking) computers together. The cables are often described as CAT 5 & CAT 6 patch cables or just Ethernet cables.

For the past 15+ years or so we have been able to use WiFi to connect our computers together. Many improvements have been made to WiFi and it has become more reliable but because of its popularity, it is sometimes a victim of its success. WiFi (Wireless Fidelity) is just a name coined by someone to describe a “Wireless” (without wire) method of connecting computers using “Radio waves”. Without a doubt, WiFi is so convenient but it does have limitations and due to it being a “Radio Signal”, it does suffer reliability problems. Bluetooth is also a “Radio Signal” but very much shorter range and isn’t generally used for “networking” but it can be!

Simple Internet connection using WiFi.

Connect to the Internet and Join a Wide Area Network a.k.a.WAN.

Once you have connected your computer or computers to the ISP Router, you are connected to the Internet! To browse websites, just open a browser and enter the Website address (a.k.a.the URL). When you connect to the Internet, you can potentially connect to millions of other computers around the world. This outside (public) world can be hostile so you need to protect yourself / your PC, see Basic PC Security.

Creating a Local Area Network (LAN).

These days it is very easy If you make use of the ISP Router and built-in 4 port switch. If you have more than 4 devices that you want to network, add an extra switch with more ports. ( I have a 16 port switch connected to the ISP Gateway / router) Having a LAN, enables you to share printers and exchange information between computers. You could even set up a device for storing your photos, documents and music etc so that all computers on the LAN would be able to access this “resource”.

You could use an additional combined router/ switch/ WAP. This would allow you to create a Guest LAN. All devices connected to the Guest LAN would only be able to access the Internet and NOT your Home LAN.

Diagram below is similar to my set up but doesn’t show the firewall between the ISP gateway / router and the Switch for the “home LAN”

There’s lots of combinations. If you’re having trouble getting the WAP in the right place to get the signal in all rooms, you could use a standalone WAP that can be connected to the 2nd router either by Ethernet or if the 2nd router is also a WAP, you could connect using WiFi (it then becomes a Bridge) You just need to have a think about what you are trying to achieve and be very careful that you don’t open your LAN to the Internet. Lots of info on this site about network and Internet security.

If you’re having problems with WiFi coverage for the whole house, have a look at “Homeplug” a.k.a. Ethernet Over Mains.

© Jeff DVOIT

www.pcjudo.co.uk

www.dvoit.co.uk