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OSI Seven Layer
A
B
Application
Application
Pressentation
Pressentation
Session
Transport
Session
Router 1
Router 2
Network
Data Link
Network
Data Link
Network
Data Link
Transport
Network
Data Link
Physical
Physical
Physical
Physical
1
Physical Layer
(1)
1
0
0
1
0
1
1
+6 V
0V
2
Physical Layer
(2) RS-232C
0
0
1
1
1
0
0
1
0
1
2
3
4
5
6
7
+V
-V
Start bit
Data bits
End bit
3
Physical Layer
(3) Manchester
bit duration
0
1
1
0
1
0
1
1
0
1
0
+V
-V
4
Physical Layer
(4) Differential Manchester
1
1
0
0
1
1
0
0
1
1
1
+V
-V
0.
Signal voltage changes in the middle of the bit；
Signal voltage changes in the beginning of the bit
1.
Signal voltage changes in the middle of the bit；
Signal voltage do not change in the beginning
Control
Signal voltage do not change in the middle of the bit
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Data Link Layer
MAC information:
http://map-ne.com/Ethernet/vendor.html
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Network Layer
Some of the Routing Protocols:







RIP
RIPv2
OSPF
IGRP
EIGRP
IS-IS
BGP
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Network Layer
Routed Protocols：
 IP
 IPX
 Apple Talk
 DecNET
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Network Layer
Network Layer Address：

Hierarchical



Network Number
Host Number
Logical Address
MAC Address：
 Flat

Physical Address
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TCP/IP Model
DOD Reference Model
OSI Model
Process/Application
Application
Presentation
Session
Host-to-Host
Internet
Network Access
Transport
Network
Data Link
Physical
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TCP/IP Model
Process/
Application
Host-to-Host
Internet
Telnet
FTP
TFTP
SMTP
LPD
NFS X window
TCP
ICMP
Network Access Ethernet
SNMP
UDP
BootP
ARP
IP
Fast
Token
Ethernet Ring
RARP
FDDI
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TCP/IP Model
IEEE 802 Standard
802.1
802.2
802.3
802.4
802.5
802.6
Higher Layer LAN Protocols Working Group
802.7
Broadband TAG (Inactive)
Logical Link Control Working Group (Inactive)
Ethernet Working Group
Token Bus Working Group (Inactive)
Token Ring Working Group
Metropolitan Area Network Working Group
(Inactive)
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TCP/IP Model
IEEE 802 Standard(Cont’d)
802.8
802.9
802.10
802.11
802.12
802.13
Fiber Optic TAG
Isochronous LAN Working Group
Security Working Group
Wireless LAN Working Group
Demand Priority Working Group
Not Used
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TCP/IP Model
IEEE 802 Standard(Cont’d)
802.14
Cable Modem Working Group (Archive information
is currently being moved, not available)
802.15
Wireless Personal Area Network (WPAN) Working
Group
802.16
802.17
Broadband Wireless Access Working Group
Resilient Packet Ring Working Group
http://grouper.ieee.org/groups/802/dots.html
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Summary
OSI Model Functions:

Compression/Decompression

Encryption/Decryption

Connection Establishing/Terminating

Segmentation/Reassembly

Flow Control

Error Control

Addressing/Routing
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Summary
OSI Model Functions: (Cont’d)

Sequencing

Encapsulation/Decapsulation

Encoding/Decoding

Multiplexing

Synchronization

Positive Acknowledgement and
Retransmission (PAR)

Windowing
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Internet Protocol
First Octet Rule
Class
-----A
B
C
D
E
First Octet
------------0xxx xxxx
10xx xxxx
110x xxxx
for multicast
for research
Default
Range
Idea
Subnet Mask
---------- ----------- -----------------0~127
N.H.H.H 255.0.0.0
128~191 N.N.H.H 255.255.0.0
192~223 N.N.N.H 255.255.255.0
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Internet Protocol
Class Networks
Nodes in each network
A
128
256 x 256 x 256
B
64 x 256
256 x 256
C
32 x 256 x 256
256
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Subnet
Calss
Default Host bits
Maximum
borrowing
A
24
22
B
16
14
C
8
6
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Subnet
Example 1
172.16.40.4
255.255.255.0
10101100.00010000.00101000.00000100
11111111.11111111.11111111.00000000
AND
10101100.00010000.00101000.00000000
172 . 16
. 40
. 0
AND
0 0
1 0
0 1
1 1
Network Number
0
0
0
1
172 . 16 . 40 . 4
AND 255 . 255 . 255 . 0
172 . 16 . 40 . 0
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Subnet
Example 2
172.16.40.4
255.255.224.0
10101100.00010000.00101000.00000100
11111111.11111111.11100000.00000000
AND
10101100.00010000.00100000.00000000
172 . 16
. 32
. 0
AND
0 0
1 0
0 1
1 1
Network Number
0
0
0
1
172 . 16 . 00101000 . 4
255 . 255 . 11100000 . 0
172 . 16 . 00100000 . 0
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Subnet
Example 3
172.16.0.0 255.255.224.0
Continuous 0 to 1
Subnet Mask
11111111.11111111.11100000.00000000
172 . 16
.000xxxxx.xxxxxxxx
.001xxxxx.xxxxxxxx
.010xxxxx.xxxxxxxx
Subnets 23
.011xxxxx.xxxxxxxx
3
Valid subnets 2 -2
.100xxxxx.xxxxxxxx
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Total nodes in each subnet 2 .101xxxxx.xxxxxxxx
Valid nodes in each subnet 213 -2 .110xxxxx.xxxxxxxx
Abbreviation: 172.16.0.0/19 .111xxxxx.xxxxxxxx
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Subnet
Example 4
172.16.0.0 / 255.255.255.0
Continuously borrowing
bits from the right
Subnet Mask 11111111.11111111.11111111.00000000
172 . 16
.00000000.xxxxxxxx
.00000001.xxxxxxxx
.00000010.xxxxxxxx
Subnets 28
Total nodes in each subnet 28 . …
.11111111.xxxxxxxx
172.16.0.0/24
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Subnet
Network Number: The first node of each network
Broadcast address: The last node of each network
172.16.0.0/20
172.16.32.0
172.16.47.255
172.16.0.0/24
172.16.15.0
172.16.15.255
172.16.0.0/28
172.16.15.64
172.16.15.79
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Subnet
Class C
Subnet mask
Valid
Subnets
Valid
nodes
Total valid IP Saving
nodes
255.255.255.192
2
62
124
255.255.255.224
6
30
180
255.255.255.240
14
14
196
255.255.255.248
30
6
180
255.255.255.252
62
2
124
√
25
Subnet
Best IP Saving
Class
A
B
C
Subnet Mask Total usable nodes
(212-2) x (212-2)
255.255.240.0
255.255.255.0
(28-2) x (28-2) = 2542
255.255.255.240 (24-2) x (24-2) = 196
 borrowing bits = left-over bits
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Subnet
/17 =255.255.128.0 /25 =255.255.255.128
/10 =255.192.0.0 /18 =255.255.192.0 /26 =255.255.255.192
/11 =255.224.0.0 /19 =255.255.224.0 /27 =255.255.255.224
/12 =255.240.0.0 /20 =255.255.240.0 /28 =255.255.255.240
/13 =255.248.0.0 /21 =255.255.248.0 /29 =255.255.255.248
/14 =255.252.0.0 /22 =255.255.252.0 /30 =255.255.255.252
/15 =255.254.0.0 /23 =255.255.254.0
/16 =255.255.0.0 /24 =255.255.255.0
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Subnet
IP 10.128.32.64, Find its broadcast IP
/8
/10
/11
/12
/13
/14
/15
/16
10.255.255.255
10.191.255.255
10.159.255.255
10.143.255.255
10.135.255.255
10.131.255.255
10.129.255.255
10.128.255.255
/17
/18
/19
/20
/21
/22
/23
/24
10.128.127.255
10.128.63.255
10.128.63.255
10.128.47.255
10.128.39.255
10.128.35.255
10.128.33.255
10.128.32.255
/25
/26
/27
/28
/29
/30
10.128.32.127
10.128.32.127
10.128.32.95
10.128.32.79
10.128.32.71
10.128.32.67
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Subnet
Find the broadcast address of the following IP：
128.1.2.3/29
128.5.6.7/28
128.4.5.6/30
128.3.4.5/26
128.10.15.20/27
128.5.160.3/23
128.6.7.10/25
128.7.6.4/22
128.6.27.8/21
128.1.2.7
128.5.6.15
128.4.5.7
128.3.4.63
128.10.15.31
128.5.161.255
128.6.7.127
128.7.7.255
128.6.31.255
16.65.30.1/20
16.65.60.1/19
16.65.140.1/18
16.65.100.1/17
16.65.1.1/16
16.65.0.0/15
16.65.3.4/14
16.65.100.200/13
16.65.128.255/12
16.65.31.255
16.65.63.255
16.65.191.255
16.65.127.255
16.65.255.255
16.65.255.255
16.67.255.255
16.71.255.255
16.79.255.255
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Subnet





IP and Subnet Mask work together to define the
neighborhood(network range) of that IP
Router uses routing table to make path decision
Routing table records the relationship of network
number and the router’s interface (port); not the
IP to the port
Intermediate routers forward packets based on their
destination network number, not the destination IP
The final router uses IP to get the MAC of the
destination host, then uses the destination MAC to
deliver the packet (within a frame)
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Private IP
10.0.0.0
1 x 224 = 224 IP
(10.0.0.0~10.255.255)
172.16~31.0.0
16 x 216 = 220 IP
(172.16.0.0~172.31.255.255)
192.168.0.0
256 x 28 = 224 IP
(192.168.0.0~192.168.255.255)
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Summary
When IP and its subnet mask are known, the following
can be determined:
· The subnet number of this subnet
· The broadcast address of this subnet
· The range of this subnet
· The maximum subnets allowed by this mask
· The number of hosts in this subnet
· Borrowing bits and total network bits (/number)
http://www.johnscloset.net/cgi/dictionary.pl?Netmask
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