OSI
MODEL
Open Systems Interconnection was developed by ISO in
1977.
-Why a layered Network Model?
-Reduces
complexity
-Standardizes
interfaces
-Facilitates
modular engineering
-Ensures
interoperable technology
-Accelerates
evolution
-Simplifies
teaching and learning
-Media Access Control Address is a 48-bit length address in Data Link Layer (Layer 2)
of the OSIModel.
-MAC Address in physical address, typically burned-in to
hardware at the factory and should be Unique.
-In a computer, MAC address is usually address of Network
Interface Card (NIC) or wireless adaptor.
-Expressed as 6 groups of 2 hexadecimal digits, separated
by hyphens (-) or colons (:)
- The
first 6 digits are Organizationally
Unique Identifier (OUI), represent the vendor.
- The
rest of the digits are vendor-assigned end-station
address for identifying the
thernet Hardware.
thernet Hardware.
-
For example: 02-00-4D-4F-00-50
LAYER 3- IP ADDRESS
-IP (Internet Protocol) address is address in Network Layer (Layer 3) of the OSI model.
-Different from MAC address, IP address is logical and
flexible, mean that we can change and adjustIt.
-There are 2 kind of IP Address
- IPv4
-
32 bits length.
-
Totally 2 ^ 32 = 4,294,967,296 (4.2 billion) address.
-IPv6
-128
bits length.
-Totally
2 ^ 128 = 340,282,366,920,938,463,374,607,431,768,211,456 (340
decllion) Addresses.
decllion) Addresses.
IPv4 ADDRESSING
-IPv4 has 32-bit of address length.
-Expressed in dotted decimal notation, divided into 4
pieces of 8-bit (octet):
- For
example: 192.168.1.1
-
Binary: 11000000
10101000 00000001 00000001
- Each
octet’s value: 00000000~11111111
(0~255)
- IPv4
range: 0.0.0.0~255.255.255.255
IPv4 SUBNETTING
-Subnetting is a way to separate and distribute IP addresses into multiple blocks (subnets):
-
Smaller networks are easier to manage.
-Overall
traffic is reduced.
- You
can more easily apply network security policies.
-Hosts that located in the same subnet can communicate
with each other directly without involvement Of the router.
IPv4 SUBNETTING (Cont.)
-Subnet Mask is used to determine the size and IP range of the subnet:
-
Network ID or Network IP is the first IP address of a subnet, used for
identifying a network.
-
Broadcast IP is the last IP address of a subnet, use for sending broadcast
traffic to all hosts
In the
subnet.
-Host
IPs are IP addresses that we can actually assign on end hosts, it is between Network
ID
And
Broadcast IP.
-Subnet Mask uses the same notation as IPv4 address:
-For
example: 255.255.255.0
-Binary: 111111111111111111111111 00000000
-This
subnet mask is 24
bits.
CALCULATE AN IP RANGE
-Let’s try this example:
-IP
Address: 192.168.1.1
-Subnet
Mask: 255.255.255.0
-Calculation steps:
1.
Convert IP Address and Subnet Mask to Binary.
2. Count
how many “1” in Subnet Mask bits, remain particular number of bits in IP
Address
Unchanged
and use them as IP Prefix.
3.
Replace the rest bits in IP Address to 0 to find Network ID.
4.
Replace the rest bits in IP Address to 1 to find Broadcast IP.
5.
Convert Network ID and Broadcast IP back to Decimal.
6. Host
IPs are between Network ID and Broadcast IP.
DECIMAL TO BINARY CONVERSION
192.168.1.1
![](file:///C:\Users\KIMYAN\AppData\Local\Temp\msohtmlclip1\01\clip_image004.gif)
1 1 0 0 0 0 0 0
1 0 1 0 1 0 0 0
0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 1
Result: 11000000 10101000 00000001 00000001
BINARY TO DECIMAL CONVERSION
11000000 10101000 00000001 00000001
![](file:///C:\Users\KIMYAN\AppData\Local\Temp\msohtmlclip1\01\clip_image011.gif)
1 1 0 0 0 0 0 0
128 + 64 = 192
1 0 1 0 1 0 0 0
128 + 32 + 8 = 168
0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 1
Result: 192.168.1.1
CALCULATE AN IP RANGE (CONT.)
-Convert to Binary
-IP Address: 11000000 10101000 00000001 00000001
-Subnet Mask: 11111111 11111111 11111111
00000000
-Subnet Mask
has 24 “1”, so IP Prefix is 24-bit length:
-IP Prefix: 11000000 10101000
00000001
-Network ID: 11000000 10101000
00000001 00000000
-Broadcast IP: 11000000
10101000 00000001 11111111
-Convert
back to Decimal:
-Network ID: 192.168.1.0
-Broadcast IP: 192.168.1.255
-Host IPs: 192.168.1.1 ~ 192.168.1.255
-Total Addresses: 256
-Usable
Addresses: 256 – 2 = 254
IP CALCULATION TOOLS
-Calculator in Windows
-Use Programmer Mode
-Online IP /
Subnet Calculators:
- http://www.subnetmask.info
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