Time
13 hours 57 minutes
Difficulty
Beginner
CEU/CPE
14

Video Transcription

00:01
Hello and welcome back. Dicey Anyone interconnecting Cisco networking devices Part one.
00:06
This is absurd. 152 Transmission control Protocol or TCP.
00:11
I am dreading Dara one. I'll be your instructor for this course. In the last video, we just went over the 1.5 less an overview some pre assessment questions.
00:20
In this episode we'll be covering the transmission control protocol or the connection oriented protocol. So common TCP applications how it does air recovery in connection establishment and termination
00:33
in the learning objectives. We're gonna be going over multiplexing using ports, common TCP applications, the connection establishment and termination,
00:42
a recovery and a bit about window in.
00:46
It was called a quick pre assessment question here. What TC port does Http use Give it a few seconds to positive video.
00:57
All right, Hopefully you got the port 80
01:00
Port 20 ones. FTP port 25 SMTP
01:06
Import 53 is D N s.
01:10
It's a little bit of multiplexing here. The well known ports that it is defined through one truth 1024.
01:17
So the destination port is actually gonna be a well known port
01:21
and a sore sport is gonna be a random on nusport.
01:26
So if we look at one of these connections down in the bottom right here, the far left I p address,
01:32
it's fine
01:34
with the random port, and then you'll see the destination with the port 80. So it's an http
01:38
uh, socket.
01:42
So socket is three things. It is an I p address the transport protocol in a port numbers. So if we look at their we see TCP have I p address, and then we have a port number
01:52
for both him.
01:53
So if you guys are curious is command down to the bottom, right is actually net stat space minus a nbp space TCP
02:05
but you to run the minus B parameter, you actually had to be running in as an admin. So fear those credentials. Otherwise, you can just run A and B p space TCP
02:14
come connect.
02:16
All right,
02:17
So let's say we have a PC here
02:21
who is connecting to
02:24
a H T t
02:29
p
02:31
f g p.
02:34
And let's say lastly,
02:37
it's just gonna do a T FTP server,
02:42
which so these two will actually be TCP,
02:46
and this last one will be beautifui
02:50
ew dp
02:52
for the airport 69
02:57
do you see hE
03:00
21
03:01
and this will be 80.
03:06
See, Cp.
03:07
So the biggest thing is all these connections going back and forth, How does the computer can't differentiate Those
03:13
is gonna be with these unused port numbers down here.
03:16
Right? Because if you have multiple open their tabs open it was, say, an Internet explorer and chrome or fire Fox.
03:23
And they're all coming into port 80
03:25
is not gonna know which tab to put that information in.
03:30
So uses these sockets to actually determine where it needs to go.
03:39
All right, so it's uncommon. TCP applications that we're gonna be using here is Port 2021 is gonna be FT. Peak in data and control 22 is sshh. Welch will use quite a bit
03:51
23 attendant will use it a little bit. Kind of go over it, but it shouldn't be used very often. He should be tried to be a void. Exit sends everything over clear Text
04:00
SMTP is poor 25 which is a simple male transfer protocol.
04:04
Port 53 is D N s. This one is actually TCP and UDP depending on what it does.
04:11
So you d p is just your normal and it's look up style thing. The zone trance for zone transfers for servers is on TCP
04:18
and again. Port 80 is http. 1 10 is pop three year post office protocol
04:26
1 61 is the simple network Management Protocol for 43 is https or SSL,
04:32
and 514 is the CIS log. So the four that you're gonna be want to be really familiar for this course is sshh,
04:41
Telnet, SMTP and Cece Log.
04:46
All right, So the way that
04:47
TCP establishes connections here was drawn up on top right there. We have here
04:53
your sin flag
04:56
and that the PC is gonna initially sent to the servants say, Hey, let's synchronize.
05:01
And then the server's gonna send back the synchronized acknowledgement flag in the TCP header.
05:08
If only the PC sends back to Acknowledgments And okay, so it's usually considered the three way handshake,
05:14
So TCP connection, it connected. Termination,
05:17
So PC one for sons. The acknowledgment. I want to be finished. Field pc two cents. Okay, I received your finished flag.
05:26
Here is my finish leg and then PC one will send back the final one, which is the acknowledgment that you receive the finished flag.
05:35
So with
05:36
reliability in their recovery, the way that's uses, what sequence of acknowledgement numbers
05:42
in the TCP header.
05:45
All right, so if we have PC one here
05:49
and pc to over here,
05:53
he's gonna send a sequence number of 1000
06:00
sequence and the PC to says, Okay, I received that.
06:03
I am ready for
06:05
bit 2000 Next
06:09
acknowledged.
06:12
And he sends back sequence 2000
06:17
and so on and so forth until I've done communicating.
06:25
So their recovery. There's a few different versions here, but the one working recovering is me with a little bit with the transmission timer.
06:31
But also it's gonna use windowing a little bit. So
06:34
again we have PC
06:38
PC. Let's say he has
06:42
the sequence of 1000
06:45
2000
06:47
and 3000. See the Windows 3000 lights here.
06:51
But let's say
06:54
so. Let's say over 2000 here gets knocked out its loss in transmission.
07:00
All right, so that server is going to come back and say, Hey,
07:04
I need
07:05
2000.
07:08
Your acknowledgment.
07:10
This is okay. And here is the sequence 2000 again.
07:16
This is cool. Okay, Now I am ready for a bit 4000 because I already have 3000 here,
07:25
so I can realize that it actually already has that
07:30
That's a little bit about window in here. So that was going a little bit about what we saw earlier, where it was able to spend send 3000 bites before the was wait before I would wait for an acknowledgment from the server
07:43
so it could actually send instead of going one back, back and forth, you know, 1000 bites here to acknowledgement, with 1000 miles to a sequence of 1000 bites
07:51
back in acknowledgement, he can actually say, Okay, the server can say, OK, you have a window of 3000 so it sends 3000 bison
08:00
and the piece of white, intelligent or season acknowledgment of those
08:03
until it opens up a window.
08:07
Now they don't want to sit there, wait so usually the window to serve Well, actually, you say,
08:11
Senator, acknowledgment before the windows actually full. That way they can continue to send trend that or transmit data consistently.
08:20
So let's say the computers, you know, it has more speed. Now there's less going on. It's it can increase the window to 4000 bites, so you know it can wait until 4000 bites or Senate before it sends an acknowledgement.
08:33
That's what's called a sliding window.
08:35
So what? This is it's kind of a way for the allows the host to tell the sender
08:41
how much Dad I could send without waiting for an acknowledgement.
08:46
All right, so the post assessment here what three flags air used in the TCP connection establishment.
08:54
Excuse me? Which two flags are used?
09:01
All right, you got me soon and at Because, remember is the three way handshake. It is the sin,
09:07
Cenac and ek.
09:11
And in the next episode, we're gonna be going over the user data Can Portico or UDP.
09:18
And as always, if you guys have questions, you need help or you have some
09:22
funny photos for me going to shoot me a message. Otherwise,
09:28
thank you for watching this course, and I look forward to teaching for the rest of it.

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