TCP/IP and OSI model

The Network Interface layer of the TCP/IP model coincides with what layer(s) of the OSI model?

Data link (layer 2) and Physical (layer 1).

Which layer of the OSI model does a bridge use to make decisions about forwarding data packets?

Data link (layer 2). This represents communication at a MAC-address level and forwards packets on Layer 2 devices, like a bridge.

Which TCP/IP layer performs addressing and routing to different networks?

Network Layer

Which layer of the OSI model establishes, manages, and terminates connections?

Session layer.

TCP/IP Model

Stands for Transmission Control Protocol/Internet Protocol. A set of protocols used to connect network devices to each other. The TCP/IP model is made up of four layers: 1. Application Layer (top) 2. Transport Layer 3. Network Layer 4. Network Interface Layer

Network Interface Layer (TCP/IP):

The bottom layer of the TCP/IP model. This layer establishes how data should be physically sent throughout the network, and includes physical devices such as cables and hardware.

Network Layer (TCP/IP)

The second layer from the bottom of the TCP/IP model. This layer defines the logical transmission of protocols for the whole network. The main protocols that live in this layer are internet protocol (IP), internet control message protocol (ICMP), and address resolution protocol (ARP).

Transport Layer (TCP/IP):

The second layer from the top in the TCP/IP model. This layer is responsible for the end-to-end transport of data. The protocols that live in this layer are transmission control protocol (TCP) and user datagram protocol (UDP).

Session Layer (OSI):

This layer is responsible for connection establishment, session maintenance, and authentication.

Application Layer (OSI):

This layer is responsible for network applications (like HTTP or FTP) and their production of data to be transferred over the network. Ex: You open a web browser on your laptop and type www.wgu.edu into the search bar.

Explain what happens when accessing a website with the OSI model:

-Layer 7 (application): You open a web browser and type www.wgu.edu in the search bar. -Layer 6 (Presentation layer): The command is then sent to Layer 6 to be encrypted as it is sent (and decrypted when received by the webserver) -Layer 5 (session layer): Establishes connection between your laptop and WGU's server and maintains it while you accomplish your tasks on the website. -Layer 4 (Transport Layer): Data is transferred and is then segmented and numbered to send the data across the network in sizes the network can handle and to reassemble it in the correct order by the webserver. -Layer 3 (Network Layer): Receives the segments and transmits them across the network as packets. As you are accessing the website, Layer 3 adds the source and destination IP addresses to each individual packet. The destination IP address will be the router on the network that will move data off the local network. The series of routers between that router and the destination server will determine how the packet is moved across various networks between them. -Layer 2 (Data Link Layer): Receives the packets and adds physical addressing by adding sender and receiver MAC addresses to each data packet. This information forms a unit called a frame. -Layer 1 (Physical Layer): Receives the frames and data and sends them via the local media (copper wires, fiber-optic cables, etc.) to switches, routers, etc, along the network path. All of this takes a matter of microseconds to achieve.

The Application layer of the TCP/IP model coincides with what layer(s) of the OSI model?

Application (Layer 7), Presentation (Layer 6), Session (Layer 5).

OSI Model

The OSI (Open System Interconnection) model consists of a seven-layer architecture that organizes the sending of data from hosts across a network. This model was developed after the TCP/IP model to provide greater granularity of networking assignments within the model. The Layers are: 1. Application (top) 2. Presentation 3. Session 4. Transport 5. Network 6. Data Link 7. Physical

Application Layer (TCP/IP):

The top layer of the TCP/IP model. This layer is responsible for the communication protocols between nodes. The protocols in this layer include hypertext transfer protocol (HTTP), Secure Shell (SSH), and network time protocol (NTP), among many others.

Data Link layer (OSI):

This layer is responsible for the error-free delivery of data to the receiving device or node. This layer is implemented through the use of devices such as switches and bridge devices, as well as anything with a network interface, like wireless or wired network cards.

Physical Layer (OSI):

This layer is responsible for the physical connections of the devices in the network. This layer is implemented through the use of devices such as hubs, repeaters, modem devices, and physical cabling.

Network Layer (OSI):

This layer is responsible for the transmission of data between hosts in different networks, as well as routing of data packets. This layer is implemented through the use of devices such as routers and some switches.

Presentation Layer (OSI):

This layer is responsible for translating data from the application layer into the format required to transmit the data over the network as well as encrypting the data for security if encryption is used.

Transport layer (OSI):

This layer provides services to the application layer and receives services from the network layer. It is responsible for the reliable delivery of data. It segments and reassembles data into the correct order for it to be sent to the receiving device. It may also handle the reliable delivery of data and any retries of data that are lost or corrupted (for example, TCP does this). This later is often called the heart of OSI.

The Transport layer and Network layer of the TCP/IP model coincides with what layer(s) of the OSI model?

Transport (Layer 4) and Network (Layer3)