So in DCP, we are marking at layer 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 selector values still exist.
So as an example, if it's set to this, that's IP precedence of one or class selector one.
But in addition, they have what are called assured forwarding classes.
We have assured forwarding class one, assured forwarding class two, three and four.
So we have these new classes should forwarding class one, two, three and four.
This number indicates the first three binary bits in the type of service field, but assured forwarding
classes have numbers such as 012.
And three so should forward in class one actually has three values.
There's f.
One one af one two.
And if.
One, two, three.
So the first three binary bits gives you your class.
So if one the second two binary bits gives you the second number and this is known as the drop probability,
how probable is it that your traffic will be dropped within class AF one?
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 shared forwarding class.
Two We also have AF two, one, af two, two and AF two, three.
The same is true for class three and class four.
The higher the first number, the more important your traffic, but the higher the second number within
a class such as AF one, one or AF one two or af one three, the less important your traffic, the more
likely that it will be dropped.