1
00:00:01,220 --> 00:00:08,770
So the phone once again is sending a layer to marking to the switch using edited at one Q.

2
00:00:08,810 --> 00:00:13,050
The markings in binary are in the range 0 0 0.

3
00:00:14,000 --> 00:00:18,980
All the way to triple 1.

4
00:00:19,280 --> 00:00:27,380
So in binary it looks like this in decimal they'll have values like this and I'll add five here because

5
00:00:27,380 --> 00:00:29,320
that's one used by voice.

6
00:00:29,690 --> 00:00:38,510
So an editor at 1 q header has a field called a priority field for so called cos it's three bits and

7
00:00:38,510 --> 00:00:46,850
size values on this range on the same way when you get to a traffic light and it's red you stop or when

8
00:00:46,850 --> 00:00:49,250
it's green you go.

9
00:00:49,640 --> 00:00:54,410
These markings in of themselves don't mean anything.

10
00:00:54,410 --> 00:00:57,650
It's the interpretation of the marking that counts.

11
00:00:57,650 --> 00:01:04,460
We've all agreed that a red light means stop and a green light means go in the same way the convention

12
00:01:04,460 --> 00:01:08,520
is that voice is marked with a cost value of five.

13
00:01:08,540 --> 00:01:10,340
That's true in Cisco environments.

14
00:01:10,340 --> 00:01:14,610
If you have phones from other vendors they may use a cost of six.

15
00:01:15,290 --> 00:01:22,610
So you need to ensure that your phones and your switches and your routers are configured to agree.

16
00:01:22,610 --> 00:01:24,760
What do these values mean.

17
00:01:24,800 --> 00:01:31,160
So the idea with marketing is we marking packets to indicate it to another device how important that

18
00:01:31,160 --> 00:01:32,630
data is.

19
00:01:32,630 --> 00:01:39,290
So when the packets are sent from Sichuan to switch to as an example switch to can read the packets

20
00:01:39,290 --> 00:01:43,520
and see that they're marked with a cost of five and then prioritize them accordingly.

21
00:01:43,520 --> 00:01:46,960
So prioritize tries them as important voice traffic.

22
00:01:47,150 --> 00:01:54,440
Now one of the problems with editor the one key layer to markings is it requires editing at one Q trunk

23
00:01:54,440 --> 00:02:02,630
puts a link such as this between a switch and a router maybe using a rod at port on a switch which means

24
00:02:02,930 --> 00:02:06,200
that edit to the one Q trucking is not used.

25
00:02:06,200 --> 00:02:13,400
If you send traffic across a serial link as an example or when edited to add one Q tagging is not used.

26
00:02:13,400 --> 00:02:17,920
You may as an example be using BPP or HDL see on a serial link.

27
00:02:18,560 --> 00:02:22,210
So layer two markings such as editor 1 q aren't.

28
00:02:22,220 --> 00:02:25,880
End to end and therefore you may want to use a layer 3 marking.