1
00:00:01,320 --> 00:00:08,280
So in DCP, we are marking at layer three, we're using the type of service field in an IP version for

2
00:00:08,280 --> 00:00:15,930
header, for example, but only six bits of the header are used when the six bits are set to zeros.

3
00:00:15,930 --> 00:00:17,430
That's known as best effort.

4
00:00:18,300 --> 00:00:20,360
Class selector values still exist.

5
00:00:20,370 --> 00:00:28,650
So as an example, if it's set to this, that's IP precedence of one or class selector one.

6
00:00:28,740 --> 00:00:33,300
But in addition, they have what are called assured forwarding classes.

7
00:00:33,540 --> 00:00:39,210
We have assured forwarding class one, assured forwarding class two, three and four.

8
00:00:39,480 --> 00:00:46,020
So we have these new classes should forwarding class one, two, three and four.

9
00:00:46,440 --> 00:00:52,470
This number indicates the first three binary bits in the type of service field, but assured forwarding

10
00:00:52,470 --> 00:00:57,510
classes have numbers such as 012.

11
00:01:00,930 --> 00:01:06,780
And three so should forward in class one actually has three values.

12
00:01:07,620 --> 00:01:08,760
There's f.

13
00:01:10,200 --> 00:01:15,960
One one af one two.

14
00:01:17,920 --> 00:01:19,180
And if.

15
00:01:20,190 --> 00:01:21,300
One, two, three.

16
00:01:21,900 --> 00:01:25,950
So the first three binary bits gives you your class.

17
00:01:25,950 --> 00:01:34,980
So if one the second two binary bits gives you the second number and this is known as the drop probability,

18
00:01:35,310 --> 00:01:40,780
how probable is it that your traffic will be dropped within class AF one?

19
00:01:40,800 --> 00:01:47,010
The higher the number, the more likely of your traffic being dropped within this class.

20
00:01:47,310 --> 00:01:53,610
When this congestion and you've set up the right mechanisms, this traffic will be dropped first, then

21
00:01:53,610 --> 00:01:57,900
this traffic and then that traffic within a shared forwarding class.

22
00:01:57,900 --> 00:02:02,880
Two We also have AF two, one, af two, two and AF two, three.

23
00:02:02,910 --> 00:02:06,030
The same is true for class three and class four.

24
00:02:06,270 --> 00:02:13,440
The higher the first number, the more important your traffic, but the higher the second number within

25
00:02:13,440 --> 00:02:21,480
a class such as AF one, one or AF one two or af one three, the less important your traffic, the more

26
00:02:21,480 --> 00:02:23,220
likely that it will be dropped.