1
00:00:00,390 --> 00:00:07,650
The TCP IP model is a model with four layers, which is for both modeling current Internet architecture,

2
00:00:08,070 --> 00:00:12,960
as well as providing a set of rules that govern all forms of transmission over a network.

3
00:00:13,920 --> 00:00:19,950
DARPA, an agency of the United States Department of Defense, created it in the 1970s.

4
00:00:21,130 --> 00:00:26,230
This model was being made at the same time the Ossi model was created.

5
00:00:27,650 --> 00:00:35,330
The TCP IP model is not the same as U.S. high model, however, it was influenced by the model, which

6
00:00:35,330 --> 00:00:38,540
is why many of the names of the different layers are the same.

7
00:00:39,720 --> 00:00:47,070
So we can simply say that the TCP IP reference model represents reality in the real world, whereas

8
00:00:47,070 --> 00:00:51,360
the Ossi reference model represents an ideal, OK?

9
00:00:52,460 --> 00:00:56,270
So these are the main differences of the TCP IP reference model.

10
00:00:57,760 --> 00:01:04,690
The three top players in the USA model, that is the application layer, the presentation layer and

11
00:01:04,690 --> 00:01:11,890
the session layer are not distinguished separately in the TCP IP model, which only has an application

12
00:01:11,890 --> 00:01:13,960
layer above the transport layer.

13
00:01:15,440 --> 00:01:20,270
TCP IP corresponds to Ossi layer for the transport layer.

14
00:01:21,610 --> 00:01:27,070
IP corresponds to a subset of ozone layer three, the network layer.

15
00:01:28,100 --> 00:01:36,560
TCP IP makes no prescriptions as to the link layers below IP, while Ossi specifies two layers.

16
00:01:37,480 --> 00:01:44,170
The physical address, commonly the Mac address, which is located in a special field in the datalink

17
00:01:44,170 --> 00:01:51,880
layer header, changes as a packet passes from one device to another, for example, from the source

18
00:01:51,880 --> 00:01:57,490
PC to a switch to a router to another switch, and then finally to the destination PC.

19
00:01:58,710 --> 00:02:05,370
However, the original IP source and destination addresses do not change when transiting the network

20
00:02:05,370 --> 00:02:11,580
because the packet is stripped of its layer three header only when it goes beyond a router.

21
00:02:13,280 --> 00:02:20,630
When it stays within the same land, it only passes through switches which decaf isolated at the layer

22
00:02:20,630 --> 00:02:23,390
to heter containing the Mac address.

23
00:02:24,310 --> 00:02:31,780
So as a result, the header changes as the packet is re encapsulated, as does the Mac address Fields'.