Original subtitles

Unit cash, multicast and broadcast.

So in IPV for addressing there are broadcast patterns for devices to find or know about each other.

So we're going to talk about three of these in pretty good detail.

IP communication broadcasts.

Right.

So the questions become what is unique cast and what is multicast and what is broadcast and what is

IP directed broadcast?

Well, they're all related, but they're definitely different.

So we're going to split them up and take the answers one by one.

All right.

What is unique cast?

Well, if you look at the IPv4 address structure.

Each has a network partition and a host partition.

Right now, there are different ways to send packets from the source device, and these different transmissions

affect the destination of these IPv4 addresses.

Unit gas transmission refers to one device sending a message to another device in a one to one communication.

So the eunuchs pack it as a destination IP address, which is the unit cast address to a single receiver.

Now, since the packet is generated from only one source, the source IP address can only be a unit

cast address.

And this, by the way, applies to all, regardless of whether the destination IP address is unique,

fast broadcast or multicast.

So when you look at the picture on the screen, it consists of three hosts.

You see a printer and a router connected to a switch.

Now, the animation is going to show the host with the IP address one seven two two one six Dot 4.1,

sending a unique cast packet to the IP address one seven two two one six eight four two five three.

So when the Switch receives the frame, it forwards it to the printer with the IP address.

One seven two Dot one six point forty two five three.

IPv4 unit cast host addresses are addresses in the range 1.1.1 that one to two to three, not 255.255.255.0.

However, like I said earlier, there are many addresses in this range that are reserved for special

purposes.

All right, smarty pants, what's multicast?

Multicast transmission reduces traffic by allowing a host to send a single packet to a select group

of hosts that subscribe to the multicast group.

Hmm.

So a multicast packet is a packet whose destination IP address is a multicast address.

So IPv4 reserved addresses two to 4.0 dot 0.0.

All the way through two three nine Dot 255.255.255.0 is a multicast range.

So host receiving certain multicast packets are called multicast clients, these multiclass clients

use services requested by the client program to subscribe to the multicast group.

Each multicast group is represented by a single IPv4 multicast destination address.

So when an IPv4 host becomes a member of a multicast group, the host processes packets arriving at

the multicast address and arriving at the individually allocated unique cast address.

Oh yes.

See routing protocol such as OSP use multicast transmissions.

For example, OPF rf enabled routers communicate with each other using the address due to 4.00 to fire,

which is reserved for the OSP rf multicast address.

Only OSP, if enabled devices handle these packets with a destination, IPv4 address of two to 4.0 Dot

0.5.

All other devices ignore these packages.

Okay, so what is broadcast?

Well, broadcast transmission just refers to one device sending a message to all devices on the network,

you know, one to all type of communication.

Now, a broadcast packet is either all ones or 30 to one destination IP addresses in the host portion.

Now, by the way, IPv4 uses broadcast packet.

However, there are no broadcast package in the next version, up IPV six.

But you already knew that, right?

Now, unit cash package must be handled by all devices in the same broadcast domain.

Broadcast domains identify all hosts in the same network segment.

So broadcasts can be directed or limited, a directed broadcast is sent to all hosts on a given network.

For example, a host on the one two one six board zero slash 24 network sends a packet for one seven

two to one six four two five five.

A limited broadcast is sent for 255.255.255.0 to 555 and by default, routers do not forward broadcasts.

So broadcast packets do use resources on the network and allow each receiving hosted on the network

to process this packet.

Therefore, broadcast traffic should be limited so that the performance of the network or the devices

is not adversely affected.

So because routers allocate broadcast domains, dividing networks into subnet can improve network performance

by eliminating excessive broadcast traffic.

IP directed broadcasts, yeah.

Now, in addition to the broadcast address, 255.255.255.0 255, there is a broadcast IPv4 address for

each network.

So this address is called a forwarded broadcast uses the highest address on the network.

This is the address where all the host bits are one.

For example, the forwarded broadcast address four one nine two zero one six eight eight one zero slash

24 is one nine two eight one six eight.

Not one, not two five five.

So you see, this address provides communication to all host on that network.

A host can send a single packet targeting the network's broadcast address to send data to all hosts

on the network right from there.

All right, now, a device not directly connected to the target network will forward an IP directed

broadcast just as unique cast IP packets are sent to a host on that network.

So I want to direct a broadcast packet reaches a router directly connected to the target network.

Well, this packet is then broadcast to the target network.

Oh, and by the way, due to security concerns and previous abuse by malicious users, router broadcasts

are turned off by default as of Cisco iOS version 12.0 with a global configuration command.

No IP directed broadcasts.

Got it!

All right.

Well, see, that's a lesson up to now we've learned a Unix multicast broadcast.

Pretty cool, huh?

So see you in the next lesson.