OSI Standard Protocol
• Open System Interconnection (OSI) standard
was originally used when creating network
protocols (TCP/IP, IPX, etc.)
• The OSI standard uses a 7layer
network model
to describe network addressing, data analysis,
and network hardware capabilities
• Benefits of using a layered model are:
– Each layer of the OSI model is responsible for specific
tasks
– Various technologies can interoperate
in a
standardized way
OSI 7Layer
Model
• 7) Application layer
• 6) Presentation layer
• 5) Session layer
• 4) Transport layer
• 3) Network layer
• 2) Data link layer
• 1) Physical layer
OSI Media Layers
MAC Addresses
• MAC Addresses (Media Access Control)
are unique addresses assigned to NICs
– First part of the MAC address is assigned to
the manufacturer of the hardware;
– The rest of the address is determined by the
manufacturer;
– Devices, that are not manageable (e.g., HUBs
and some switches) do not have MAC
addresses
• Example: 00:0C:42:04:9F:AE
MAC Addresses (part 2)
• MAC addresses are used for addressing in
the Data Link Layer (Layer 2) of the OSI
network model (This means all
communications in one LAN segment use
MAC addresses)
• MAC addresses are not used to group
hosts on the network together
• Analogy: MAC address is like person’s
social security number
IP Addresses
• IP addresses are used for logical addressing in
the Network Layer (Layer 3) of the OSI network
model.
• IP addresses
– are 32 bits long (used to be globally unique)
– are referenced by humans via dotted decimal
notation, one number per 8 bits (1 octet or byte), e.g.,
159.148.147.1
• Analogy: IP address is like a person’s mailing
address.
IP Netmask
• IP netmask (with the IP address), defines which
IP addresses are reachable directly
• There are 3 types of netmask notation
– Byte notation
– Binary notation
– Bit notation
• Examples:
– (byte) 255.255.224.0 = (binary)
11111111.11111111.11100000.00000000 = (bit) /19
– (byte) 255.255.255.0 = (binary)
11111111.11111111.11111111.00000000 = (bit) /24
– (byte) 255.255.255.248 = (binary)
11111111.11111111.11111111.11111000 = (bit) /29
IP Networks: Example
• IP address/netmask: 192.168.3.14/24
IP value (binary):
11000000.10101000.00000011.00001110
Netmask(binary):
11111111.11111111.11111111.00000000
Network (binary):
11000000.10101000.00000011.00000000
Network address: 192.168.3.0/24
Last = Broadcast address: 192.168.3.255
Usable IP address: 192.168.3.1 192.168.3.254
Subnetting Examples
• Network address/mask 192.168.1.0/24
– host addresses 192.168.1.1254
– broadcast address 192.168.1.255
• SubNetwork
address/mask
192.168.1.0/25
– host addresses 192.168.1.1126
– broadcast address 192.168.1.127
– SubNetwork
address/mask 192.168.1.128/25
– host addresses 192.168.1.129254
Address Quiz
• Given IP address/netmask: 192.168.23.37/28
• Calculate:
• Network
address_______________________
• Number of usable IP addresses ________
• Broadcast
address_______________________
Assigning an IP Address
IP Address Lab
• Add the IP address 192.168.X.254/24 to
the router's ether1 interface
• Add the IP address 192.168.X.1/24 to your
laptop's Ethernet interface
• Check the network using the “ping”
command
• From laptop: Start >
Run >
ping
192.168.x.254 t
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