So in DCP we are marking at least three.
We're using the type of service field in an IP version for header for example but only six bits of the
header are used when the six bits are set to zeros.
That's known as best effort class elect a value still exist so as an example if it's set to this that's
IP precedence or one or class selector one.
But in addition they have what are called assured forwarding classes.
We have a shared forwarding class of one should forwarding class to three and four.
So we have these new classes should forwarding Class 1 two 3 and 4.
This number indicates the first three binary bits in the type of service field but assured forwarding
classes have numbers such as 0 1 2
and 3.
So should forwarding Class 1 actually has three values.
There's a f 1 1 F 1 2 and a f 1 3 so the first 3 binary bits gives you your class so a f 1.
The second two binary bits gives you the second number and this is known as the drop a probability.
How probable is it that your traffic will be dropped within class a f 1.
The higher the number the more likely of your traffic being dropped within this class.
When this congestion and you've set up the right mechanisms this traffic will be dropped first then
this traffic and then that traffic within a should forwarding class to you.
We also have a f to 1 a f to two and a half to three.
The same is true for Class 3 and class for the higher the first number.
The more important your traffic but the higher the second number within a class such as a f 1 1 or f
1 2 F 1 3.
The less important your traffic the more likely that it will be dropped.