Original subtitles

We can also answer this question How many broadcast domains are they in network one.

So if I go back all the way to the original OP message and then click capture forward the OP a message

is sent to the Hub.

Notice it's a broadcast at or layer two.

So what happens to broadcast traffic it gets flooded so we have one broadcast domain because I broadcast

sent to a hub is flooded.

So single broadcast domain in network one

we can also prove that by rerunning a simulation so let's rerun the simulation.

I'm only going to look at AAP and ICMP traffic but on P.S. 1 what I'm going to do now is send a broadcast

to 10 1 1 255 so this is a broadcast I'll only send two packets notice the broadcast traffic is sent

to the hub when we look at the packet source address is P.S. 1 we can see that again by looking at the

MAC address.

So notice the MAC address is P.S. 1 destination is a broadcast.

So the destination MAC address is set to that destination IP address is set to a broadcast 255 255 255

in Packet Tracer.

Source IP address is P.S. 1 Notice the broadcast goes to everyone.

So it's a single broadcast domain these devices will reply back but the traffic is flooded out of all

ports.

Notice we're getting a collision here so recent of the simulation and let's look at another problem

if P.S. 1 sends a ping to P.C. for and P.S. 2 sends a ping to P.C. for what's going to happen so they

both sending packets into the network

in this example.

P.S. to send an OP because it doesn't know the MAC address of P.S. For so here's the actual frame.

A quick recap of terminology to be precise and to be correct for the CCMA exam and to leave one in the

OSA model.

We talk about butts at least two in the US eye model we talk about friends and to layer three we talk

about packets and at least four we talk about segments and then we typically talk about the data at

higher layers.

I'm often using terms interchangeably here but if you want to be very precise about terminology at a

later one it puts a layer to its frames Layer 3 its packets at layer for its segments.

So notice another layer to the frame has a destination address of a broadcast.

That's causing problems with the frame that was sent by P.S. 1.

We've got a collision taking place here so there's a problem with the frames because of the collisions

only one device can access the network at any time so here.

P.S. 1 is sending the ICMP message and a reply is sent back to P.S. 1

so run the simulation again before I do that.

I'm going to make sure that P.S. To can ping P.S. 4 so make sure that it's OP cache is populated so

both.

P.S. To and P.S. 1 have P.S. fours MAC address in the OP cache and then what I'll do in simulation mode

is get P.S. 1 to ping P.S. 4 and get P.S. To 2 ping P.S. 4 so they both can send an ICMP packet.

When that hits the hub we have a collision.

You have a single collision domain when you have a hub.

So a hub is a single broadcast domain as well as a single collision domain.

We're going to have problems with lots of collisions taking place as you add more and more devices to

a hub.

So be careful with hubs.

They are single collision domains and single broadcast domains so we can save for questioning 11 network

1 equals a single collision domain.

Be careful using hubs today we don't use hubs in wide infrastructures we use switches which we'll see

in a moment.

Have multiple collision domains.