Alright, let's jump into this challenge.
Once again, we are going to be faced with converting between per-hot behaviors
and decimal and
maybe the other way around.
And we're actually given a kind of interesting challenge question in this.
So as the question above says, we're going to start by converting some of our
per-hot
behaviors into decimal.
So this is similar to what we did earlier.
Not only earlier in this skill, but earlier in the course.
And so we've got AF11.
So let's remember our equation.
We have 8x plus 2y. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We have 8x plus 2y.
And so I'm going to multiply the first by 8, multiply the second by 2, add them
together.
8 times 1 plus 2 times 1, that's just 8 plus 2.
And so AF11 has a decimal value of 10.
Meanwhile AF33, same equation here.
We're going to say it's 8 times 3 plus 2 times 3.
That would be the first 3 here, second 3 here.
And so that's 24 plus 6, and the answer there would be 30. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
And so that's 24 plus 6, and the answer there would be 30.
So that's the first set of equations.
Let's also not forget how we do a CS.
For example, if we have a CS2, we simply multiply this number by 8.
So that would be 16.
And of course, expedited forwarding, there's no equation for it because there's
no numbers
in this per-hot behavior name.
And so we just have to remember that it's 46.
There we go.
So that's the first question.
Which assured forwarding per-hot behavior represents a decimal value of 36? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Which assured forwarding per-hot behavior represents a decimal value of 36?
So now we're starting sort of here, and we're trying to get back to an assured
forwarding
name, a per-hot behavior at the end.
And so how do we go about doing that?
We're going to do the same thing here.
We're just going to use division and try to get back to this concept of having
so many
eights and so many twos.
The good news is, as long as this is a valid assured forwarding number, we'll
all
always be able to have a sum number of eights and some number of twos, and the WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
always be able to have a sum number of eights and some number of twos, and the
math will
work out.
So what we do to start with is we want to find the eights.
And the way we do that is we simply divide by 8.
And so 36 divided by 8, we could say is 4 and a half, but ultimately it's 4 as
our whole
number, and it has a remainder of also 4.
Because 36 divided, well, let's do it the other way.
8 times 4 would be 32, and 32 is still 4 off from 36. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
8 times 4 would be 32, and 32 is still 4 off from 36.
So that would be our answer.
So this is the number of eights.
Next, we need to find the number of twos.
And we're going to look at that by taking our remainder.
And so now we have a 4, and we need to know how many twos are in the 4.
Well, at that point we just divide it by 2, and so 4 divided by 2 is 2.
So we have our first number, 4, we have our second number, 2.
This is AF42.
Now how confident am I? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Now how confident am I?
Well, I just need to run this in reverse.
I've got my equation up here.
I can double check this.
So it would be 8x plus 2y, 8 times 4, plus 2 times 2.
So this is 32, this is 4, 32 plus 4, does indeed equal 36.
So decimal value of 36 converts to AF42, and the way I do that is again, divide
by 8 to
get my whole number, divide the remainder by 2 to get the rest.
So we do have a process in place for that. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So we do have a process in place for that.
Lastly, this is the interesting one.
A packet has a DSCP tag of decimal 22.
What decimal tag would keep the packet in the same queue while giving it the
lowest drop
probability?
Now we do have to make an assumption here, and that is that in order to stay in
the same
queue, we're going to keep within the same AF priority.
So we need to figure out what this AF priority value is.
Is it a 1?
Is it a 2?
Is it a 3?
Or is it a 4? WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Or is it a 4?
Because those are our four priority values.
And if we figure out, for example, that happens to be a 2 or a 3, well then we
just need
to make sure that we find the same AF3x, let's say, we just need to find the,
what is it,
the lowest drop probability?
All right, so we're going to do the same process we just did here because we
have to
start by converting this to an AF per hot behavior.
So I'm going to expedite this a little bit.
We're going to take 22.
We're going to divide it by 8 to get a whole number and remainder. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
We're going to divide it by 8 to get a whole number and remainder.
So that would just be 2, that's 16, with a remainder of 6.
So 16 plus 6 should be 22, it is.
And so that's my first number.
Then I'm going to take this remainder, divide it by 2, and that is a 3.
So that's interesting.
So I've got a 2 and a 3, which means I'm in AF23.
So I actually am in the priority field of 2.
So the assumption here is that within this queue, we have 21, 22, and 23. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
So the assumption here is that within this queue, we have 21, 22, and 23.
This is typically how we do things from a real world perspective.
If we're using our per hot behaviors, I'm going to put all of the same priority
value
into the same queue.
But up here, we already have 23 as being the highest likelihood to drop a
packet.
So what decimal tag would keep the packet in the same queue, namely, still
starts with
a 2, while giving it the lowest drop priority.
So that should be targeting AF21.
Now notice these are not decimal values, these are per hot behaviors. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
Now notice these are not decimal values, these are per hot behaviors.
So I need to get to AF21 from AF23.
Well, if I think about it, there's two ways to do this.
I could just convert AF21 into decimal.
That's 8x plus 2y.
So that's 16, 8 times 2, 2 plus 1 is 2.
There we go.
There's 18.
So 18 is going to be our answer.
I could do it that way, just recognizing that.
I could also recognize that simply going from 1 AF down to the next and down to
the next,
I'm just subtracting 2 each time. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I'm just subtracting 2 each time.
That's all I'm doing is I'm removing 1 from the 2's column, so to speak.
And therefore, I'm subtracting 2.
So I start with 22, right?
Yeah, 22.
And so then I go to 20, and then I go to 18.
So either way, I end up with the same answer.
The big caveat to this is I couldn't just do that from the start, because I
didn't
know for sure whether I could go, you know, if this happened to be AF22, I
could only
go down by 1.
I wouldn't be able to go from AF22 down to 20. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
I wouldn't be able to go from AF22 down to 20.
I couldn't go to.
I had to figure out where I was in the array of AF2Xs, if that makes sense.
But by finding out that I was AF23, I knew I could step down twice, which gets
me from
decimal 22 down to decimal 18.
So that last question was more just a way to make us kind of think outside the
box and
make sure that we've got all this math down.
It's not straightforward math.
There's more of those kind of high school math era word problems where you have
to take
math and apply it to a real world situation. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
math and apply it to a real world situation.
So hopefully just a lot of fun with this math.
I don't know if I'm the only one who says that, but this kind of math and this,
you
know, converting back and forth once you get that process down actually is
pretty fun
and pretty straightforward.
But if any of this tripped you up, then just make up your own problems.
Convert AF41 to decimal and then go back and check your work and make sure that
you did
it correctly or take a decimal value like 36 and just kind of go through it and
the more
we do it, the more comfortable we're going to be. WEBVTT X-TIMESTAMP-MAP=LOCAL:00:00:00.000,MPEGTS:900000
we do it, the more comfortable we're going to be.
So that brings us to the end of this skill and this review on quality of
service.
If any of the quiz questions or this challenge may be shown a light a little
bit on some
areas of weakness, that's not a bad thing.
That's great.
In fact, it allows us to go back and review the content as much as needed in
order to
shore up those knowledge gaps and make sure that we're good to go not only
moving forward,
but then later on when we're preparing for our exam in the last stages.
I hope this has been informative for you and I'd like to thank you for viewing.