So before we move on to ports and are different protocols that work with different port numbers, we need to understand that there are some protocols which don't work with port numbers. They're like are like our TCP and UDP and our routing protocols there some protocols that don't really have port numbers.
as we'll talk about it in a little bit, we have some of our protocols that work with port numbers, and these protocols work with port numbers because they need to know where to deliver information. Port numbers are essentially a on I P address, plus an additional number,
and that additional number allows us to have
sort of like how a country has multiple different ports. It allows our computer to manage multiple different data streams at one time, so those data streams still have to have a place to go. They have to have a logical place to send data to. That's consistent every single time. So we know that
this data corresponds with this particular activity and those that's what our ports do. Our ports allow us to receive different data streams from different protocols, but there's some protocols that don't work with ports because of the layer that they work on. And these are our network
and data link Leo Protocols or TCP eyepiece Sweet
network and data link Leia Protocols. Now,
we brought back up our chart
And what's our network layer on our data link layer? Well, our network layer and our data link layer of roos I model are
right here and right here there are layer to
and our layer three.
We have our net. Always I model of seven, a seven layer
ideological model of how a network works together in the form of layers. And we have physical layer, which is one Please do not throw sausage, pizza away. Physical data link, network transport session, presentation and application.
These protocols work either on the network layer or the data link layer. The data link layer
protocols especially, will have port numbers because they're not going to necessarily be communicating via an I P. Address. And you need to have an I P address to have a port number.
Port numbers are identified as I p address colon port number. So you don't have that I p address. Where does that port number go to? Which of the
millions billions of I P addresses. Does this court port norm number correspond with? So that's not gonna help us are networking protocols. Some of our networking protocols don't use port numbers either because there's not a particular port that they could deliver to. In this case, they just need to deliver a message or attempt to deliver
some sort of information. So we used these different protocols.
we have I, C M P I, G and P R I, C M P and I GMP are going to be on our network layer.
They're gonna be network protocols,
we're gonna put under our data link. It's really sort of like a layer 2.5 almost because it's going to negotiate between networking and data link layer.
now that I've gone on enough about why these are special protocols, let's actually talk about what they do. Um,
ICMP stands for Internet control message protocol,
and what I see and P does is allows us to deliver errors and queries to other particular I P addresses to determine if a service is available or to determine if there's some sort of error going on you'll see ICMP messages in Ping requests.
Ah Ping is simply an ICMP echo request to a particular target.
and I see and P protocol icmp protocol.
When you think about it, doesn't really transmit data. It's really just a packet of It's just a packet with information.
So when you think of data packets, we think of packets that transfer things like files or e mails or Web pages. And then you have other packets which are just
message protocol packets on this case or ICMP packet.
So if we send an I C and P Echo request packet, what we're doing is we're essentially sending a message to a target computer saying, Can you hear me?
If that if that other side can see us, it's going to send an echo request back now we conform at certain routers. We conform at certain servers not to respond to these, because maybe we don't want somebody to know if it's there. Maybe we don't want someone in numerator on our network or enumerating are router, so we don't want them to send.
We don't want them to allow ICMP echo requests back.
Maybe We don't want someone trying to run a denial of service attack on our on our router by sending millions of ICMP requests to that one router because responding to an ICMP request does take network bandwidth, and it does take a little little bit of computing power. But if it has to do that to millions of different locations,
all of our network computing power and all of our bandwidth. And we can't service our clients. So sometimes we will disable ICMP messages back. So just because you're not getting an echo request back doesn't necessarily mean that object is an online
R I, C and P requests Internet control message protocol. That's going to be a network layer protocol. It's not gonna have a port number associated with it, and it's gonna help us to deliver air messages and query messages. I see A and P we're going to use for things such a Czar Ping requests are trace route requests are
two devices to see if a service is available to see if a to see if a particular device is up.
So we have our icy and peas and well just remember that a ping
We're requesting an echo back, letting letting us know if this device is online. So exam question
Which network protocol does a ping request to use?
Does it use ICMP? Does it use http? Or does it use
And our answer would be digging being icmp
because a ping request is an ICMP echo request.
Now, next, we have i g m P I g m p stands for Internet group management protocol, and I GMP is going to be
We don't even have it up here. It's gonna be a multi cast
So Internet Group Management.
We've talked about how multi cast is one too many and we need a way to manage those multi cast members and we need a way to manage membership in multi cast addresses. Remember, a multi cast addresses an I P address that we send, uh, we send a message to, and that message goes to
multiple different locations, multiple different computers. I GMP manages those different. There's different addresses, manages how those messages go out to those different computers