What is OSI Model? — Transcript

Full transcript

1. 0:02OSI stands for open systems
2. 0:05interconnection and is a conceptual
3. 0:08framework for how applications
4. 0:09communicate over a network there are
5. 0:12seven layers within the model in the
6. 0:15layers depiction is used to help users
7. 0:17identify what is happening within a
8. 0:19networking system
9. 0:24[Music]
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16. 0:51one
17. 0:54the OSI model layers are typically
18. 0:56described from the top layer down the
19. 0:59layers are described as application
20. 1:02presentation session transport network
21. 1:07data link and physical
22. 1:11these layers are provided by a mixture
23. 1:13of network car drivers operating systems
24. 1:16applications and networking hardware
25. 1:19that facilitate the transmission of
26. 1:21signals over Ethernet fiber-optic Wi-Fi
27. 1:24or other wireless protocols
28. 1:28will describe the layers from the top
29. 1:31down as the top layer is the application
30. 1:34layer or layer 7 this is the layer that
31. 1:38most users interact with and will
32. 1:40recognize the application layer provides
33. 1:43network services to the end-user these
34. 1:47services are protocols that work with
35. 1:49the data the client is using one of
36. 1:52these protocols may be HTTP that is used
37. 1:56with web browsers such as Google Chrome
38. 1:58Firefox and Internet Explorer other
39. 2:02examples of applications that use this
40. 2:04layer are Office Outlook and Skype
41. 2:09all of those interactive applications
42. 2:11provide a set of services that allow the
43. 2:14application layer to supply data to and
44. 2:17receive data from the presentation layer
45. 2:23the presentation layer or layer six
46. 2:26performs the uncomplicated task of
47. 2:28syntax processing or converting data
48. 2:31from one format to another for example
49. 2:35consider you're ordering something from
50. 2:37an online store these transactions are
51. 2:40typically handled in a secure
52. 2:42transmission which means that the data
53. 2:44passing between the store or the website
54. 2:47application will transmit encrypted data
55. 2:50to the presentation layer that will need
56. 2:52to be decrypted and processed this layer
57. 2:56handles translating the data from the
58. 2:59top layer which is presented in
59. 3:01application format to network format and
60. 3:04vice versa
61. 3:07after the presentation layer processes
62. 3:10the data from one format to another the
63. 3:13information is then passed to the
64. 3:14session layer or the application layer
65. 3:17depending on whether the data is
66. 3:19transmitting or receiving
67. 3:24at the session layer or layer five the
68. 3:27construction direction and conclusion of
69. 3:30connections between devices occur this
70. 3:34layer supports multiple types of
71. 3:36connections as well as being responsible
72. 3:38for authentication and reconnection if a
73. 3:41network interruption should occur after
74. 3:44the session is established the data then
75. 3:47passes to or from the transport layer
76. 3:52the transport layer or layer 4 is
77. 3:55responsible for the transmission of data
78. 3:57across network connections this layer
79. 4:01coordinates how much data to send how
80. 4:03fast where it goes and these sorts of
81. 4:06things
82. 4:08of the most widely known protocols for
83. 4:11internet applications these services may
84. 4:14be provided by transmission control
85. 4:16protocol or TCP and user Datagram
86. 4:19protocol or UDP other protocols may
87. 4:23provide additional capabilities
88. 4:25including error recovery data flow and
89. 4:29retransmission once the transport layer
90. 4:32has completed its function the data is
91. 4:35then passed to or from the network layer
92. 4:40the network layer or layer three handles
93. 4:44the routing of the data after the data
94. 4:47arrives at this layer each frame of data
95. 4:49is examined to conclude if the data has
96. 4:52reached its ultimate target the layer
97. 4:55sends data to the correct destination on
98. 4:57outgoing transmissions and receives
99. 5:00incoming transmissions as well the IP
100. 5:03portion of tcp/ip is the commonly known
101. 5:07network layer for the Internet
102. 5:10this layer also manages the mapping
103. 5:12between logical addresses and physical
104. 5:15addresses for IP addresses this is
105. 5:18accomplished through address resolution
106. 5:20protocol or ARP the data is then passed
107. 5:25to the next required layer which is the
108. 5:27data link layer
109. 5:30the datalink layer or layer two is
110. 5:33considered the most complex of the
111. 5:35layers this layer is often divided into
112. 5:39sub layers called media access control
113. 5:41or mac and logical link control or LLC
114. 5:46the layer sets up links across the
115. 5:49physical network when this layer
116. 5:51receives data from the physical layer it
117. 5:53checks for transmission errors and then
118. 5:56packages the bits into data frames from
119. 6:00there this layer manages the physical
120. 6:02addressing methods for the mac or LLC
121. 6:05layers an example of the mac layer
122. 6:08includes 802.11 Wireless specifications
123. 6:12as well as Ethernet
124. 6:15at the data link layer the data passes
125. 6:18to or from the final layer in the OSI
126. 6:21model which is the physical layer
127. 6:26the physical layer or layer one is the
128. 6:29electrical or physical layer of the
129. 6:31model this layer encompasses the network
130. 6:34cables power plugs cable pinouts
131. 6:37wireless radio frequencies connectors
132. 6:40transceivers receivers repeaters pulses
133. 6:44of light electric voltages etc
134. 6:49when troubleshooting problems this is
135. 6:51typically the first place to start is
136. 6:54the device plugged in is the wireless
137. 6:57card working
138. 7:00at this layer the model transmits the
139. 7:03digital data bits from the source or
140. 7:05sending devices physical layer over
141. 7:08network communications media which can
142. 7:10be electrical mechanical or radio to the
143. 7:14receiving or destination devices
144. 7:16physical layer
145. 7:19the OSI model is a guide for developers
146. 7:22and vendors to smooth the progress of
147. 7:24developing communication products and
148. 7:26software programs that will work in
149. 7:28cooperation with a commonly established
150. 7:31model once you understand the model you
151. 7:34can then understand which protocols and
152. 7:36devices will be compatible with one
153. 7:39another
154. 7:44want to learn
155. 7:46see programming in an easy-to-understand
156. 7:49format and take your career to the next
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158. 7:56[Music]