OSI model Vs. TCP/IP model

What is the first things the 'Transport' layer does ?

* Takes Data:PDU from the layer above * Identifies which 'Application' is making the request and what 'Service' will receive it * *Application makes request / Service will receive them * We identify them using 'Port' addresses * *Src * *Destination * We stamp every PDU, with a source and destination address

What to the OSI:Transport layer use address for ?

* To identify who is getting the Data:PDU * Used to identify the 'Service' or 'Application' ( of the Top layers) * Uses port addressing (src/destination)

What are the different OSI:Physical layer infrastructure ?

* Wired infrastructure ** uses 'Ethernet' standard for communication in LAN/WAN ** Vs. LAN technologies such as Token Ring, FDDI and ARCNET. ** Ethernet cable ** IEEE 802.3 standard * Wireless infrastructure * Wifi * 802.11x (a,b,g,n) * Wired to Wireless infrastructure communication * PDU:data-frames pass an 802.11 (WLAN) medium, and are being converted to 802.3(Ethernet) or vice versa * Refer: https://en.wikipedia.org/wiki/Ethernet

What is the responsibility of the top 3 layer of the OSI ?

* present PDU as 'Data' * Encryptions and Compressions * in binary format

How do the TCP:IP model layers map equivalents to OSI model

Application layer-> OSI 5,6,7

What are the layers of the TCP/IP model

Application, Transport , Network-Access

What is the Data Link layer?

As its name suggests, this layer is concerned with the linkages and mechanisms used to move data about the network, including the topology, such as Ethernet or Token Ring, and deals with the ways in which data is reliably transmitted.

What is a PDU ?

Each layer of the OSI model formats the data it receives to suit the functions to be performed on that layer. In general, the package of data that moves through the layers is called a Protocol Data Unit (PDU). However, as the data is reformatted and repackaged, it takes on unique names on certain layers.

Reference

Evernote: https://www.evernote.com/shard/s42/nl/4558384/149579db-d36c-45fb-9b5f-d3ea768c0a42/

What does the OSI Model describe?

In essence, the OSI model prescribes the steps to be used to transfer data over a transmission medium from one networked device to another.

What is Application layer

The Application layer provides services to the software through which the user requests network services. Your computer application software is not on the Application layer. This layer isn't about applications and doesn't contain any applications. In other words, programs such as Microsoft Word or Corel are not at this layer, but browsers, FTP clients, and mail clients are.

What is the Transport layer?

The functions defined in this layer provide for the reliable transmission of data segments, as well as the disassembly and assembly of the data before and after transmission.

What is the Session layer?

This layer also controls single or multiple connections session for each end-user application Sessions are most commonly implemented on Web browsers using protocols such as the Zone Information Protocol, the AppleTalk Protocol and the Session Control Protocol. These protocols also manage session restoration through checkpointing and recovery. The session layer supports full-duplex and half-duplex operations and creates procedures for checkpointing, adjournment, restart and termination

What is the Presentation layer?

This layer is concerned with data representation and code formatting.

What is one of the protocol which produces the PDU:Segment in the OSI:Transport layer ?

* TCP (Transmission Control Protocol) * sacrifices time over reliability * if we are producing a PDU, there should be a protocol on how to produce this and done by TCP

What are the layers of TCP/IP model groups as compared to OSI model ?

* TCP-IP:Application layer (OSI:Application + OSI:Presentation + OSI:Session) ** produces PDU:data * TCP-IP:Transport layer (OSI:Transport) ** produces PDU:segment * TCP-IP:InterNetwork layer (OSI: Network) ** produces PDU:packet * TCP-IP:Network Access layer (OSI: DataLink + OSI:Physical layer) ** produces PDU:frames

What is the Alternate model of the OSI model ?

* TCP/IP model * describes the same layers as OSI but more grouping * OSI makes more fine grained of layers so that the cryptographer and the UI are not written by the same person in the TCP/IP:Application Layer, more separation of concern and speciality.'

What are is Addressing protocol used by TCP protocol ?

* Port Addressing **port Source-Address **port Destination-Address

Why do we segment the data ?

* Security * Performance * allows multiple segments at the same type : Multiplexing

What are is Addressing protocol used by protocol 'IP' ?

* Source-Address of the n/w * Destination-Address of the n/w

What is the PDU Conversions in the encapsulation communication process ?

* (encapsulation: communication down the stack) * PDU:Data --> PDU:Segment --> PDU:Packet --> PDU:Frame * (Frame is the only time u use a 'header' and 'trailer'

What happens at the OSI:Physical layer ?

* Conversion of the all the abstract data 'bits' in the layer above, to something real 'signals' ** PDU:frames consumed by 'hardware drivers' to produce physical 'signals' * well written 'hardware drivers' are needed for correct translation and use given hardware to full potential. * done by NIC card (Network Interface Card) of the 2 devices * uses standards like : 802.11x or Ethernet standard/protocol * NIC's should use the same identical standards to make use of the full bandwidth of the device NIC communication * Eg: Buying a NIC card which matches full standards of Wireless router NIC

What does the OSI:Network layer from communication from the layer above ?

* Converts Segments:PDU into Packets:PDU * IP protocol is used for this conversion * IP protocol is also used for routing data across the nodes to destination endpoint

What is the name of the communication-process up and down the OSI stack ?

* Encapsulation comm-process (Down the stack) * De-capsulation comm-process (Up the stack)

What are the layers of the OSI model ?

* Layer-7: Application * Layer-6: Presentation, * Layer-5: Session, * Layer-4: Transport, * Layer-3: Network, * Layer-2: Data Link, * Layer-1: Physical "All People Seem To Need Data Processing" — a top-to-bottom reminder. "APS Transports Network Data Physically" — APS refers to Application, Presentation, and Session. This one separates the upper and lower layer group

What are is Addressing protocol used by protocol 'Ethernet' ?

* NIC card src/destination * Address burned into the NIC * At the OSI:DataLink layer

What if the PDU of the OSI layers ?

* PDU of (Application, Presentation, Session ) ** Data * PDU of (Transport) ** Packet * PDU of (Data-Link, Physical)

Why do we have a TCP/IP model when we have an OSI model

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What is the full form of OSI

Open Systems Interconnection Reference Model

What is the Physical layer?

The Physical layer's name says it all. This layer defines the electrical and physical specifications for the networking media that carry the data bits across a network.

What is the Network layer?

This is the layer on which routing takes place, and, as a result, is perhaps the most important OSI layer to study for the CCNA test. The Network layer defines the processes used to route data across the network and the structure and use of logical addressing.

What are some of the principles of the OSI model?

Whenever a discrete level of abstraction is required, a new layer should be created. Each layer of the model should carry out a well-defined function. The function of each layer should define internationally standardized protocols.

What to the OSI:Network layer use address for ?

to identify devices on the network