CCNA Part 7: An Introduction to IP Addressing
An Introduction to IP addressing
An IP address is made up of a network portion and host portion. If we use the analogy of a Postal address we can say the network portion is the same as a postal code, the postal code area contains multiple houses and businesses, the street address points to a specific house or business which is the host portion on a network
In Binary the IP address looks like this:
IP addressing and Classes
Class Private IP Range
A 0.0.0.0 127.255.255.255
B 128.0.0.0 191.255.255.255
C 192.0.0.0 223.255.255.255
D 224.0.0.0 239.255.255.255
E 240.0.0.0 255.255.255.255
Class A Networks
The IP range 0.0.0.0 – 127.255.255.255 is using a Class A network. For example the IP address 10.0.10.10 is an example of a class A IP address. So using 10.0.10.10
In the above screenshot we can see the network portion is 8bit and the host portion is 24bit
Class B networks
Class B Networks has a range from 128.0.0.0 – 191.255.255.255, in class B addresses the first 2 octets (first 16bits) are the network portion and the next last 2 octets are the host portion. On a class B network you can host about 65000 hosts
Class C Networks
Class C networks have the IP range 192.168.0.0 – 223.255.255.255, in a class C network the first 3 Octets (first 24 bits) are the network portion the last 4 bits are the host portion. Class C networks were designed for small businesses. In a class C network we have the possibility to create many networks but only a maximum of 255 Host IDs
Class D networks
Class D networks have an IP range from 224.0.0.0 – 239.255.255.255, it’s a 32bit address and it’s a Multicast address
A example of a multicast address
224.0.0.6 Is a specific address which is used for the protocol OSPF – Open Shortest Path First. This protocol allows users to connect to this multicast address to stream information from it. So what is it used for exactly? It can be used for streaming companywide a video presentation. A video feed can basically be sent to a server, the server sends a single stream on to the network with a specific multicast address, then what happens all the devices on the network can join into that one stream of traffic using the multicast address. This how Netflix or YouTube works, this is how every user connects to a stream. The multicast stream does not work with Internet; we can only do this with IPv4 on our internal networks. Only a well-seasoned Network engineer would use multicast and its not something a low level Network technician would normally be messing around with.
Classless Addressing
Classless addressing uses something called the subnet mask, the subnet mask is a kind of hack to solve the problem of running out of Classful addresses. The subnet mask is used to determine the network portion and host portion of our network address.
So using the IP address 203.0.113.10 I have converted it to binary as in the shown in the following screenshot. What we do is look at the binary number shaded in light blue, we put all ones in here, and where the shading is orange we put zeros. Now we can translate the Binary numbers to decimal.
Adding up the bits in the first 3 octets = 255.255.255 and the last octet all zeros = 0
So our subnet mask is 255.255.255.0 which is class C network
Let’s take a look at another example using 10.0.0.10. The same principle follows we have the network portion in blue and we have the host portion in orange.
Now the next example is a little different, the network portion falls in the middle of the 3rd octet. Still we apply the same principle, we convert it to binary which will mean that the when we convert the subnet mask to binary the first 2 octets will be switched to one’s, the 3rd octet as the network portion shows falls in the middle this means that the octet must have the first set of 1’s switched on and the rest 0’s and the 4th octet all 0’s.
Address Types – Ipv4
We have 3 types of IP addresses:
Network address
Host Address
Broadcast Address
Network address: is used to identify a group of hosts, but how can we identify what is the Network portion and the host portion. This is determined by looking at the subnet mask if we have the subnet mask 255.255.255.0 we can see the last octet is 0’S this means all 8 bits are set to 0. This also means when we look at the last octet in the Network IP its really set to the same as the last octet like in the subnet mask
Example
203.0.113.0 Network address all zeros in the last octet
255.255.255.0 Subnet mask all zeros again
The broadcast address
203.0.113.255 the last octet is with 255 indicating it’s a broadcast address; all devices on the network with the IP address 203.0.113.x will receive broadcast packets. The broadcast in the host portion all the bits are set to 1’s
Host addresses are the individual addresses which we set on the end devices such as routers PCs printer’s laptops tablets etc. etc, the host address what is used the most in networking, broadcasts are the least used. When the host portion is not all 0’s and not all ones you know it’s the host address. See following screenshot
Practice
What kind of address ?
203.0.113.55
255.255.255.0
It’s a host address, if we convert it to binary it looks like this
11001011 00000000 01110001 00110111 (host address)
11111111 11111111 11111111 00000000 (subnetmask)
What kind of address
192.168.10.25
255.255.255.0
11000000 10101000 00001010 00011001 (host address)
11111111 11111111 11111111 00000000 (subnetmask)
Again it’s a host address
192.168.0.10.255
255.255.255.0
11000000 10101000 00001010 11111111
It’s a broadcast address, we can see this directly because the last octet is 255 all 1’s
What kind of address
10.10.0.0
255.255.0.0
00001010 00001010 0000000 0000000
11111111 11111111 0000000 0000000
This is a network address because the last octet in the IP is 0 and when we convert 0 to binary address is all 0’s
What kind of address?
10.128.224.64
255.255.255.224
Now it gets a little tricky, it appears at first as if it’s a host address but in fact it’s a network address. If convert to binary
11000000 10101000 00001010 01000000
11111111 11111111 11111111 11100000
We can see the last octet is:
We can see the last 5 bits are all set to 0’S so it’s a network address.
Private and Public Addresses
Private Addressing – the following addresses are used in private networks – they cannot be used routed on a public network.
One other private address is 127.0.0.1 its for a local machine, we can use it to test the NIC on a PC to check if the protocol stack is working
If we open a command prompt and type ping 127.0.0.1 it should reply like this:
C:\Users\rwelsh>ping 127.0.0.1
Ping wird ausgeführt für 127.0.0.1 mit 32 Bytes Daten:
Answer von 127.0.0.1: Bytes=32 Time<1ms TTL=128
Answer von 127.0.0.1: Bytes=32 Time <1ms TTL=128
Answer von 127.0.0.1: Bytes=32 Time <1ms TTL=128
Answer von 127.0.0.1: Bytes=32 Time <1ms TTL=128
Ping-Statistik für 127.0.0.1:
Pakete: Gesendet = 4, Empfangen = 4, Verloren = 0
(0% Verlust)
Demostrating IP Address Configuration and verification
If we run the following command ipconfig /all
C:\Users\rwelsh>ipconfig /all
Windows-IP-Konfiguration
Hostname . . . . . . . . . . . . : ZAM210
Primäres DNS-Suffix . . . . . . . :
Knotentyp . . . . . . . . . . . . : Hybrid
IP-Routing aktiviert . . . . . . : Nein
WINS-Proxy aktiviert . . . . . . : Nein
DNS-Suffixsuchliste . . . . . . . : zam.kfa-juelich.de
Ethernet-Adapter LAN-Verbindung 4:
Verbindungsspezifisches DNS-Suffix: maz.kfa-forschungszentrum.de
Beschreibung. . . . . . . . . . . : Allied Telesis AT-2701FTX PCI Ethernet Adapter – 1 NIC Model
Physikalische Adresse . . . . . . : 00-15-77-AD-19-97 – MAC ADDRESS
DHCP aktiviert. . . . . . . . . . : Ja – Set to Receive IP from DHCP Server
Autokonfiguration aktiviert . . . : Ja – Set to auto negotiate speed from network
IPv4-Adresse . . . . . . . . . . : 134.94.168.221(Bevorzugt) IP address leased
Subnetzmaske . . . . . . . . . . : 255.255.248.0 Subnet mask
Lease erhalten. . . . . . . . . . : 28 October 2015 07:52:16 – Time the leased IP was given
Lease läuft ab. . . . . . . . . . : 04 November 2015 07:52:12 – Time the leased IP will be released
Standardgateway . . . . . . . . . : 134.94.168.1 – Standard gateway is simply the router
DHCP-Server . . . . . . . . . . . : 134.94.80.3 – DHCP server
DNS-Server . . . . . . . . . . . : 134.94.105.203 Primary Domain name service Server
134.94.105.204 – Secondary DNS server
134.94.105.205 – Third DNS Server
Primärer WINS-Server. . . . . . . : 134.94.80.84 – Windows Internet Name Server
NetBIOS über TCP/IP . . . . . . . : Aktiviert