Transcript Network Layer

Functions
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How long is MAC address?
How is mac address used in data communication?
What is a frame?
What does an IP address look like?
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TCP
IP
Virtual
End-to-end
Connection
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Network layer is
responsible for moving
data through a set of
networks.
Router (R) helps to
forward data through
different networks
IP protocol operates
at Network Layer
R
R
R
R
R
R
R - Router
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Large networks are divided into many small networks
Networks identified by their network addresses
◦ Example: 192.168.254.10, subnet mask: 255.255.255.0
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Network address helps to identify
path (route) through network from
start to destination.
Each network has an address, a
number that is common to all PCs
on the network
 1.0 as 1 is the common number
between 1.1, 1.2, 1.3
◦ Each PC within the network has
an address (blue ring), e.g., 1.3
What is the network address for
Eagle Server?
Router
Figure 2
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Also called Layer 3 or
Protocol address or
logical address
◦ Configurable - can be
changed by changing
TCP/IP settings
◦ Needs to change when
device is moved to a
network having different
network address
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Hierarchy in IP addressing
• IP addresses are hierarchical
• They have a defined structure
• Conceptually each IP address is a pair divided
into a prefix and a suffix
– Prefix, also called (net-id) identifies network
to which computers are attached.
– Suffix, aka, (host-id) identifies hosts within
that network.
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IP Addresses are 32
bits.
Divide into four 8
bit sections
(octets).
Convert from binary
to decimal.
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Five different classes of IP addresses
◦ A, B, C, D, E
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Class A, B and C are primary classes
 Used for assigning IP addresses
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Class D, E used for special purposes
◦ Class D for multicast addresses
 E.g., Videoconferencing
◦ Class E addresses are reserved for
experimentation
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 How to associate an address with a
class
 Look at the first group of
numbers in the dotted decimal
notation
 ClassRange
 A
0-127
 B
128-191
 C
192-223
 D
224-239
 E
240-255
Which Class has the largest Host ID and
how many bits long?
Network ID
88
Class A Network ID
Class B
Host ID
16
24
32
Host ID
10
Class C
110
Class D
1110
Multicast Addresses
1111
Reserved for experiments
Class E
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Subnet mask identifies the
boundary between netid and
hostid
Default subnet masks are
◦ Class A : 255.0.0.0
◦ Class B : 255.255.0.0
◦ Class C : 255.255.255.0
Which class has more hosts?
Which class supports more
networks?
1st octet
2nd octet
3rd octet
4th octet
Host
Host
Host
Host
Host
Class A
Network
Class B
Network
Network
Class C
Network
Network
Network
Host
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Logical ‘AND’ IP address and subnet mask to get Net-ID.
◦ E.g. IP address is 192.24.134.23, Find Network ID using
default subnet mask of 255.255.255.0 for class C
 Find the binary representation of IP address and subnet mask
 Logical ‘AND’ with subnet mask
AND
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 11000000.00011000.10000110.00010111 IP Address
 11111111.11111111.11111111.00000000 Subnet mask
11000000.00011000.10001010.00000000 Network ID
Convert binary to decimal value
◦ Network ID: 192.24.134.0
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What is the class of IP address in the figure?
223.1.1.1
223.1.1.2
Router
223.1.1.4
223.1.2.1
223.1.2.9
223.1.2.2
223.1.1.3
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Underline the network portion of each address:
Network Address
Subnet Mask
172.0.0.0
255.0.0.0
172.16.0.0
255.255.0.0
192.168.1.0
255.255.255.0
192.168.0.0
255.255.0.0
192.168.0.0
255.255.255.0
10.1.1.0
/24
10.2.0.0
/16
10.0.0.0
/16
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What is the other portion of the address?
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Underline the network portion of each address:
Network Address
Subnet Mask
172.0.0.0
255.0.0.0
172.16.0.0
255.255.0.0
192.168.1.0
255.255.255.0
192.168.0.0
255.255.0.0
192.168.0.0
255.255.255.0
10.1.1.0
/24
10.2.0.0
/16
10.0.0.0
/16
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What is the other portion of the address?
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