Digital subscriber line or DSL was one of the original broadband technologies to get high speed Internet
to the premises.
Now DSL lives on telephone lines and in my opinion it's kind of dated so let's put some sepia tune up
here right.
That's faded out.
That looks a little bit better.
DSL has been around since arguably the late 80s early 90s and pretty much nobody.
Wait a minute.
Kill the sepia guys.
Let's bring it back up.
Right.
A lot of people still use DSL and it's also on the exam so I want to take a moment and go back in time
a little bit.
I had to pull some stuff out of the vaults here to talk about DSL.
So DSL comes from telephone companies.
So a telephone company would provide a special DSL capable line.
This was the same line that your telephones were on.
Remember when telephones were hooked on RJ-11 cables and what you would do is you would plug into
your wall jack you would plug into one of these.
This is a DSL modem circa 1998.
Now what I want you to do is take a look on the back here.
So right up at the top that's a connection for an RJ-11.
And this is how we would connect up to the telephone company.
And down here I'm trying to do this blind
down here is a connection
to an RJ-45.
And this is how we would connect DSL up in our homes.
So DSL has been around for a very very long time.
There were two versions of DSL still are.
I got to keep using the past tense here.
So when we're talking about DSL we're talking about symmetric DSL where basically the download and the
upload speeds are the same.
And then we have asymmetric DSL where we have a very high speed download and a very slow upload.
You can use the same modem for these types of things.
It doesn't really make much of a difference.
So whenever you're dealing with DSL you would buy one or the other. Symmetric tended to be much faster.
The only other thing I want to show you on DSL in terms of equipment is this little guy right here.
What we're talking about here is called a DSL filter.
The problem you would run into is that the DSL signal is running on the exact same cable that your telephones
are. And again
I'm talking about telephones that you stamped into a wall and you wouldn't be able to use those phones
because you would hear all this DSL noise.
So these little guys had one job.
If you had a regular telephone.
Not that anybody remembers those.
I do. What you would have to do is you would plug this into your phone jack and then plug the phone into
this.
And this would filter out all of the DSL noise so you could call up the movie phone. I'm trying to think
of old stuff we used to do on the old telephones.
The reason I need to be careful about saying DSL is old is really boils down to this and that is there's
still a lot of people who live on DSL. Super high speed cable modems even in my house I have native Ethernet
coming into my home have begun to supplant this.
But there is one place where DSL still lives a lot of these companies that provide fiber to the premises.
Now there's exceptions to this are actually using very high speed DSL or VDSL.
It's the same technology the same signal except very very fast.
And instead of using old style copper phone lines it's using fiber to the premises.
So it may look fancy but it's really old school DSL just painted up a little bit prettier. For the exam
make sure you're aware of the existence of DSL.
Make sure you're comfortable with the idea that asymmetric is the primary way we see it.
And don't forget your filters.