Questions tagged [osi]
For questions about the Open Systems Interconnect (OSI) model defined by the International Organization for Standardization (ISO).
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How to calculate or specify these terms Throughput, Data rate, Bandwidth? [duplicate]
The term "throughput" clearly refers to the actual data received in a system. For instance, with a bandwidth of 5MHz and a channel capacity (data rate) of 10Mbps, if the received data is ...
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point-to-point or broadcast network : concrete case
What concrete rule or layer of the OSI model should be used to decide whether a network is a point-to-point network or a broadcast network?
A general definition (*) seems clear, but in practice it ...
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Clarification of relation between IPv6 and TCP [duplicate]
I thought IPv6 and TCP could be used independently, but IP does not need TCP at all, whereas TCP usually needs IP to function. Is my understanding correct? Does IPv6 need TCP to function? Looking at ...
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What happens when the sender sends more data then the advertised window by the receiver?
I am relatively new to networking. I am doubting what happens when the sender sends more data than the advertised window by the receiver. I mean that the receiver advertises the window size based of ...
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What are different encoding schemes used in gigabit ethernet?
I was reading about digital transmission, there are many steps namely:
Analog to Digital conversion
Source coding
Channel coding
Line coding
Pulse shaping
Modulation
Multiple access techniques
...
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Alternative to the Internet for a local network
Suppose we are designing a network and we want to isolate it from the Internet. Are there any alternatives to the Internet for a local network?
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IP and Ethernet endianness
I'm completely new to the topic, I've read that Ethernet sends Bytes in a Big-Endian way, but that bits are sent with Little-Endian. I've also read that IPv4 uses Big_endian order. So my question is, ...
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Why are connected switches not a good substitute for the network layer? [duplicate]
Unless I am missing something, because switches can be chained together, I am not sure why the network layer is needed. Theoretically, one can dedicate a frame to any MAC address, and assuming there ...
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Why is MPLS label added between layer 2 header and layer 3 header of OSI model and not between headers of layer 3 and 4 of OSI model?
Is there a possibility to use any other two OSI model layers' middle positions? What is the basic concept of switching of packets with MPLS on layer 2.5 of OSI Reference model?
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How Network layer routing actually works in the physical world
This is my first question here, It might be a vague or off topic, I apologise in advance, but I am happy to improve it
Basically I have a somewhat decent theoretical understanding of the OSI model. ...
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session layer in OSI model
I'm wondering to know how session layer works. In my understanding session layer is to establish active communication sessions between two devices. Based on the OSI layer model, it works layer by ...
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Is there a term for application layer protocols that are responsibilities of network engineers?
In studying network engineering, it is usually taught that network engineers are responsible from physical layer up to transport layer, that is, layer 1-4 only.
Obviously, HTTP or HTTPS are off-topic ...
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What does the network layer do at the receiver
My book (Andrew S. Tanenbaum, “Computer Networks”, Fifth Edition.) mentions while explaining the network layer that the key issue with a network layer is
determining how packets are routed from ...
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How can a router port forward and read the destination port if it's a L3 device
My understanding of port forwarding is that on the router, you configure a setting that allows you to forward all packets from external traffic with a specific destination port towards a device within ...
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Is the header of any other layer (other than the Data Link layer) is also removed and re-added when reaching a router?
Based on my understanding, when a packet reaches a router, the Data Link layer header (and trailer if there is a trailer) will be removed from the packet and a new header (and a new trailer if there ...
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What is the difference between a private IP and a MAC address? [duplicate]
I am taking a course preparing me for the Network+ certification. I wanted to know what the purpose of a private IP is when a MAC address exists. From what I understand, the MAC address is used to ...
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How to benchmark time a packet spend in each OSI layer?
I'm benchmarking latency of sending a TCP packet from a client to a server. The payload of the packet is the nanosecond timestamp (using clock_gettime() on Linux) right before the send() socket ...
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Can refer a detailed low level explaination of the OSI model at operating system level? [duplicate]
I understand the function of each layer in OSI model but I can not comprehend the inner working at the operating system level. I can't mentally picture the life cycle of data from application layer to ...
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HTTP and TCP relationship
I always wondered how HTTP knows when it has enough TCP segments in order to process a request or response.
Can someone give me more information about the process?
Thanks.
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Why need Ack flag if we already have ack number in TCP
If we have ack number so from there we can trace that how many bytes are received and which byte is need next so then what is the use of Ack flag there?
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How n level come to know the n+1 level contents?
Suppose in application layer is running some application. And application has respective source port number and destination port number. And know that n layer has no authentication to know about n+1 ...
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Why is cable classfied in layer 1 in OSI model
I am learning about the OSI model and TCP/IP Protocol.
In my understanding, they classify cables to layer 1 (Physical Layer).
But, when you connect two different devices you have to use cables no ...
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What is responsibility of different layers of OSI model and intermediate devices between sender and receiver when data packets are lost/corrupted?
Suppose sender sending some data to receiver and there are 3 routers between them. R1, R2, R3 are routers.
Now sender starts sending data packet D through it's AL, TL, N/W L, DLL,PL to router R1 ...
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EtherType multiplexing used by LLC layer
What's the type of multiplexing used by Ethernet (LLC layer)?
It says in Wikipedia "The LLC sublayer provides multiplexing mechanisms that make it possible for several network protocols (e.g. IP, ...
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Ethernet compatibility
I am improving my knowledge about the Ethernet protocol. During my study, I noticed that they are multiple versions of the protocol. Example: 2.5GBASE-T and 5GBASE-T and 100BASE-TX.
I wonder depending ...
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Why in the TCP/IP model the link & physical are one?
I'm currently learning about the OSI model and the TCP/IP models, and I was wondering: Why in the TCP/IP model the physical layer and the data link layer are combined?
I'll state how I understand the ...
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Understanding the definition of layer 2
The Wikipedia (and other sources) page about the OSI model explains layer 2 as such:
The data link layer provides node-to-node data transfer—a link between two directly connected nodes. ...
Let's ...
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Why router can't be used for converting different model of network but gateway can do this?
We know that Router can't be used for converting different model (e.g OSI model to TCP/IP or TCP/IP model to OSI) of network. It isn't a multiprotocol converter. But gateway is a highly sophisticated ...
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Does the OSI model apply anywhere else other than computer networking? [duplicate]
I try to understand the OSI model, more about why it was created and what exactly it tries to achieve.
The Wikipedia page says:
The Open Systems Interconnection model (OSI model) is a conceptual ...
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What is the goal of the OSI model? [duplicate]
I'm currently learning about the OSI model, trying to understand exactly what it is and what is the purpose behind it.
The Wikipedia page says:
The Open Systems Interconnection model (OSI model) is a ...
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What does it mean for a device to be layer n?
I've always read, the router is a layer 3 device, the switch is a layer 2 device, the hub and repeater are layer 1 devices and so on with other devices.
But what does this mean? When I started ...
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OSI model: the session initializes the communication?
A simplified example of how the OSI model works, from this page:
For example: Mr. Cooper wants to send Ms. Palmer an email. Mr. Cooper composes his message in an email application on his laptop and ...
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data link layer and encapsulation method used for specific types of media?
I was reading about the OSI model then found this question in the review questions :
Which layer of the OSI model is responsible for specifying the
encapsulation method used for specific types of ...
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In the ISO model how does the Network Layer and Application Layer knwo when frames and segments respectively are complete
I understand the general sense of the ISO model but it's my understanding that the Data from the Application layer which is usually large would get split into many TCP packets. The same thing would ...
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Do layer 2 protocols allow hosts to communicate without being on a network?
Please go easy on me as I'm just a noob in the networking space.
As far as I have learnt, layer 2 protocols use MAC addresses for communication, which doesn't really depend on what network you're in ...
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Is OSI model merely used for troubleshooting purpose? [duplicate]
I'm a student and recently started understanding OSI model, from what I understand is that OSI model is just theoretical and not really used in real world. It's mainly for troubleshooting purpose.
I'...
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Why does one say IP fragmentation is bad and to be avoided when in reality data always needs to be fragmented for MTU compatibility?
Why does one say fragmentation is bad and must be avoided due to performance issues when in reality fragmentation intrinsically occurs within the communication ?
Example:
User1 wants to send 100 000 ...
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Is NIC Layer 1 or Layer 2?
Is NIC layer 1 or layer 2?
I am asking this question because of I found both answers in different sources. Some-one says It is Layer 1. Someone says It is in layer 2. I am getting ready for advanced ...
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Is it possible to have a local area network with only layer 1 and not layer 2 of the OSI model?
I know the OSI model has seven layers. Can you consider a LAN to exist without layer 2 and just layer 1? The answers that I saw on Quora were not clear. Some of the answers on Quora came close to ...
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Why does PPP need an underlying protocol?
The Point-to-Point Protocol is (at least according to Wikipedia) a Datalink Layer Protocol.
I know that different use cases exist for it but on examining the image below from Wikipedia one can see ...
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OSI model transition between layers (data chunking across layers)
There is something I don't understand regarding the OSI model.
From what I learned, sometimes information will need to broken down into smaller pieces of information.
My question is - let's say that ...
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What is "TIME_WAIT" connection in a TCP connection and what is it's purpose?
I am requesting a webpage running on local server port 8080 and was expecting one connection to be established between the server (port 8080) and client (random port). But one additional port is also ...
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Networks theory: Layers, Services and Interfaces
I want to learn about computer networks from the bottom up.
I don't really understand the nuances of networking layers, with books mentioning that layers provide services to layers above them, but the ...
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Switch vs. Router and sequence of OSI Model [duplicate]
As I understand it:
A switch (layer 2) seems to define a LAN and a router (layer 3) enables communication between distant LANs.
A device on a LAN will give it's MAC address to the switch upon ...
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Configuration of a Dell managed switch clashes with my network understanding
I got the opportunity to play around with a Dell managed switch from the 2000 series with OS10. I tried to configure a management IP adress 10.10.12.141 (/24) according to the manual but somehow ...
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Propogation delay vs time required to send out a complete frame on channel
I was reading Data Communications and Networking by Behrouz A. Forouzan in which for simple Aloha protocol the vulnerable time given was T(fr) (time required to send out a complete frame on the ...
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Session layer role(with example) in OSI Model [duplicate]
Could someone provide some real world scenerios to understand the role played by session layer in OSI model.
Example:
Presentation Layer handles zip&unzip etc.
Similarly what does session layer ...
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Network Protocol vs Framework?
I've been a network engineer for almost 4 years now. I thought I understand what a network protocol means. but now I'm having doubts.
For me,
Ethernet is a protocol used at layer 2. there would be ...
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Unicast and Multicast MAC address convention
I need help in understanding how Unicast and Multicast MAC address is differentiated as explained in wiki.
According to what I understood, when the least significant bit is set as 0 in the first octet ...
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OSI Layer Model
I have been searching out for in depth knowledge of OSI layer model. I want to know that what information does a Application, Presentation and session layer header contains. Moreover where do these ...
