handles the transport and that will Claire's.
These are the two main layers that concern the network specialist. The network engineers.
The Transport Layer Layer number four.
It organizes data into segments. The word segment is the unit off
data at the transport layer at Layer number four, where it is a packet at layer number three and a frame at layer number two, and bits and bytes at the physical layer. Layer number one.
The transport layer is responsible for the end toe end delivery
in either reliable form or just best effort delivery.
When we try to explain the word reliable, we refer toe loss recovery,
which means that data transmitted arrives at the receiver side with no losses.
We also refer toe the Floo Control, the adjustment off the flu between the sender and receiver according to the natter conditions and according to the requirements of the
where, if there are also two data ordering, sometimes data arrive at the receiver side out of order.
Data number two before data number one. Data number one is late. Do you tow taking a congested path over the network? That's why they're the number two arrived earlier. I mean, the piece off the
this piece of data number two needs to be reordered
in reassembly process to be put in the right place after data number one.
One of the responsibilities off the transport layer is the data deed application. Sometimes data is son twice and received twice the same piece off data.
we need a form or an identify that says that this data is a duplicate. This data is another copy off a certain data that has been received. So we need a deed application process to eliminate the extra copy.
you either son and receive in a reliable communication or in best effort, delivery. It's the two modes where the transport layer works
the functionalities off the transport layer, our number one the segmentation.
The segmentation means dividing data into small fragments called segments that can be transmitted over the network.
Different networks have different maximum transmission unit there for different MTU.
The empty U defines the maximum size off one data piece carried through the network. This is the definition off. The MQ
data is being divided and transmitted to the recipient via the transport layers.
The empty you size is
agreed upon between the sender and the receiver
while establishing the connection and during the routine discovery.
is one of the parameters off the network that must be agreed upon between the sender, the receiver and the communication devices.
The second functionality off the transport layer is the reassembly. Reassembly means assembling the pieces off data arriving at the receiver side,
so the same form or the same initial form that has been
send from the center.
This reassembly is done at the receiving end.
The transport layer protocols reconstruct data into its initial for
data can be received in different order, different than the form that has been sending it.
So it is the responsibility off the transport trail to rearrange those pieces of data into the correct order. The original order, the order by which it has bean sent
the third function, like of the transport layer, is sequencing. Using the sequencing, identify roar sequencing number
tow. Avoid the loss on divided application. Each piece of data is
noted by sequence number or sequence identified.
This sequencing fixes the issue off following data. Different path is so, you know,
from the sequencing identified the correct sequence of data.
This sequencing helps in organizing data in groups, off subdivided data signals
and in identifying the order of groups off date ascending and interpretation.
The communication in the transport layer is either connection oriented. This type of communication that is called connection oriented is reliable and more secure.
It is based upon establishing two way connection between the notes. I mean the sending and receiving notes before data transmission.
For example, when a browser is tryingto open a webpage, the transport layer would send synchronization packet, tow the Web server from the browser.
The brother then expect synchronization, acknowledgement response.
When it receives this response from the server, it sends its own response to the server back.
After this process is done, the data can be transmitted.
We can hear See that no data has been transmitted Before the connection establishment is complete,
the transport layer can establish a connection. In another move that is called connection less oriented. This is a non reliable connection. This connection depends on the best effort delivery between the thunder and the receiver. No connection establishment prior to data transmission. It is less insecurity because it does not
guarantee that loss, recovery or the re ordering off later if received out of order.
It allows sometimes for data flooding for sending big chunks off data over the Net or causing it to flood to be saturated with unwilling to traffic.
But this type off connection less oriented communication is essential in some types of communication where data is really time data is delay sensitive, such as the audio data in the audio calls
or the video data in the video streaming sessions.
Now let's move to the third layer. Layer number three, the network clear.
Remember that we count layers from down to up.
This layer organizes data into packets. Now remember that data in the fourth layer is schooled,
segment and hear. If it's cool, packets
responsible this layer off end to end addressing and routing. And let's
know by heart these two words addressing and routing. These are the main functions off the network. Clear.
The network clear identifies unique logical address for each machine over the network. The address is unique. The address cannot be repeated. The address is logical
related to the geographical location off the machine. It is not a physical address it's something logical that can be changing according to the change of the geographical location off the machine.
This not clear. Select the best path for destination.
This what we call the routing process
routers. The devices that are called routers work in this network. Layer reads and understands data upto this third layer layer three they're not were clear.
This layer performs fragmentation. If segmentation was not enough to divide the data to be suitable for sending and receiving, we add another process that is fragmentation. Tow the data to divide data into smaller chunks,
not clear at the receiver. Side receives the segments off data from the transport layer.
Converts then converts segments into packets by adding the address ING information. The source is the destination
and then finds route for later to be delivered to the receiver.
that are designed to any
group of data may differ because it is being the determined based on the following.
It is either the least network overload the drought over the best route from the point of view off the quality of service, or it is the least
or according to some delivery priorities,
which means that the data has a priority more than other data, so it should take a path that is faster than other data would take.
criteria for route definition.
When we say that the network layer is responsible for identifying logical address, we must give some details about the logical address. It's a unique identifying it is bound to geographical location off the machine. It is used for end to Andrew outing. Since bound to the geographic location,
it can be changed it according to the change of the bigger geographical location off the machine.
It is not vendor oriented, as we will see in the next
lectures there. The physical address is vendor oriented.
The common example for this type of address is the I. P address in the TCP I P Protocol suit.
Let's sum up both layers. The network and transport layer the network clear. Our identifies the source machine and the destination machine in any session, while the transport layer guarantees either and toe and reliable delivery or end toe and best ever delivery for data across the same
These are the main functions off the network and transport layers in the ISA west. Sorry. Seven layers.