CCNA - Class 3 (OSI Model and TCP/IP Suite)

What is the datalink layer of OSI model?

-Provides node-node connectivity and data transfer from PC to Switch, switch to router and router to router. -Defines how data is formatted for transmission over a physical medium (ex. copper UTP cable). -Detects and possibly corrects physical layer errors. -It uses layer-2 addressing which is separate from layer-3 addressing. Switches use layer-2 addressing.

TCP/IP Network Topology Diagram

Application layers provide: Process - Process Transport layers provide: Host - Host Internet - Internet The network and datalink layers do not provide end-end, host-host communications.

What is a networking model?

Networking models categorize and provide a structure for networking protocols and standards

STP, OSPF, DHCP

STP - is a layer 2 protocol OSPF - Layer 3 protocol - Discovers the best path IP - Layer 3 DHCP - Layer 7 protocol - Helps automatically get an IP address.

What is a session layer in OSI model?

Session layer establishes, manages and terminates connections (dialogs) between local application (browser) and remote application (youtube).

What is a TCP/IP suite?

TCP/IP Model helps you to determine how a specific computer should be connected to the internet and how data should be transmitted between them. It helps you to create a virtual network when multiple computer networks are connected together. The purpose of TCP/IP model is to allow communication over large distances. TCP/IP Reference Model is a four-layered suite of communication protocols. It was developed by the DoD (Department of Defence) in the 1960s. It is named after the two main protocols that are used in the model, namely, TCP and IP. TCP stands for Transmission Control Protocol and IP stands for Internet Protocol. TCP/IP is similar in structure to the OSI model but has fewer layers. This is what is used in modern networks. However, engineers still think and talk about networks based on OSI model.

Who deals with the top 3 layers of the OSI model?

The application developers deal with the first three layers (application, presentation, session) of the OSI model to connect their application over networks.

What does the transport layer do?

The basic function of the Transport layer is to accept data from the session layer, split it up into smaller units if need be, pass these to the Network layer, and ensure that all the pieces arrive correctly at the other end. It also provides host-host communication.

How many layers are there in the OSI model and what are they?

There are 7 layers in the OSI model. 7. Application layer 6. Presentation layer 5. Session layer 4. Transport layer 3. Network layer 2. Datalink layer 1. Physical layer APSTNDP

What is encapsulation and de-encapsulation in OSI model?

When the data is moving from upper layer to the lower layer according to a network model, each layer includes a bundle of information called a header along with the actual data. This packing of data in each layer is known as the encapsulation. ... This unpacking of data in each layer is known as the decapsulation. Data created by the top 3 layers are sent down through the bottom 4 layers. While this data is sent down the bottom 4 layers, L4, L3, L2 headers are added to the data. Data+L4 Transport Header = Segment Data+L4 Transport Header+L3 Network Header = Packet L2 Datalink Trailer+Data+L4 Transport Header+L3 Network Header+L2 Datalink Header = Frame

What is a protocol?

A protocol is a set of logical rules defining how network devices and software should work.

What is adjacent layer interaction?

Adjacent-Layer interaction refers to how the adjacent networking layers in the same computer interact to each other. The higher-layer protocol uses the next lower-layer protocol to perform the service it needed; the lower layer provides a service to the layer above it.

What are the characteristics of Presentation Layer?

Data in the application layer should be translated to be sent over the network. The presentation layer's function is to translate application layer data to network format and vice versa. Ex. Encryption and Decryption of data.

What are Protocol Data Units?

Data, Segments, Packets, Frames and Bits are called Protocol Data Units. Layer 1 PDU is a bit. There are in total 5 PDUs.

What does the network layer do?

Provides connectivity between end hosts on different networks. (that is outside of the LAN) Provides logical addressing (IP address) and provides path selection between source and destination. Routers operate at Layer 3. The network layer provides the means of transferring variable-length network packets from a source to a destination host via one or more networks. The network Layer controls the operation of the subnet. The main aim of this layer is to deliver packets from source to destination across multiple links (networks). If two computers (system) are connected on the same link, then there is no need for a network layer. Network layer: Handles the routing and sending of data between different networks. The most important protocols at this layer are IP and ICMP. Data link layer: Handles communications between devices on the same network.

What is same layer interaction on OSI model?

Same layer interaction is when we look at communication between two devices using a single protocol at a single layer. ... For example, we might look at same-layer interaction between a web browser and a web server at the application layer, ignoring how the lower layers are transporting the data.

How do you compare OSI Vs. TCP/IP models?

The first three layers of the OSI model (Application, Presentation and Session) are folded into Application layer in TCP/IP. Transport layer in OSI is the same transport layer in TCP/IP. Network layer in OSI is called Internet layer in TCP/IP. Datalink and Physical layers in OSI model is folded into one and called Link layer in TCP/IP.

What is the physical layer of OSI model?

The physical layer defines physical characteristics of the medium used to transfer data between devices; Voltage levels, transmission distances, connectors, cable specifications...etc. Digital bits are converted to electrical or radio signals.

How many layers are there in a TCP/IP model?

There are 4 layers in TCP/IP model. 4. Application layer 3. Transport layer 2. Internet (NW) layer 1. Link layer

What are the characteristics of the application layer?

This layer is closest to the end-user. Interacts with software applications. Ex: Web browser HTTP and HTTPS are layer 7 protocols Functions of layer 7 include: -Identifying communication partners -Synchronizing communication These are same layer interactions.