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Questions tagged [osi]

For questions about the Open Systems Interconnect (OSI) model defined by the International Organization for Standardization (ISO).

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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 ...
PanCho's user avatar
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0 answers
14 views

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 ...
Niklas Rosencrantz's user avatar
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1 answer
44 views

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 ...
Ayush Gupta's user avatar
0 votes
1 answer
127 views

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 ...
SUNITA GUPTA's user avatar
-1 votes
1 answer
75 views

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?
Volpina's user avatar
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1 answer
297 views

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, ...
mizius's user avatar
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0 answers
27 views

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 ...
Aviv Aviv's user avatar
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1 answer
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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?
Vladimir Pejanovic's user avatar
1 vote
2 answers
517 views

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. ...
theMyth's user avatar
  • 113
9 votes
7 answers
2k views

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 ...
programmer core's user avatar
1 vote
1 answer
75 views

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 ...
Noob_Guy's user avatar
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2 answers
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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 ...
Essam's user avatar
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1 vote
2 answers
124 views

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 ...
JohnDoeyyy's user avatar
1 vote
1 answer
243 views

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 ...
user85135's user avatar
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0 answers
23 views

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 ...
CM_Key's user avatar
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2 answers
197 views

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 ...
Huy Le's user avatar
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1 answer
24 views

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 ...
Manan Chawla's user avatar
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1 answer
66 views

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.
ragnar's user avatar
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1 vote
1 answer
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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?
user83095's user avatar
1 vote
1 answer
114 views

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 ...
S. M.'s user avatar
  • 398
0 votes
1 answer
67 views

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 ...
mhdev's user avatar
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0 votes
2 answers
711 views

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 ...
S. M.'s user avatar
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1 vote
1 answer
427 views

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, ...
ragnar's user avatar
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2 answers
262 views

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 ...
ragnar's user avatar
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0 votes
2 answers
609 views

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 ...
YoavKlein's user avatar
  • 137
0 votes
1 answer
91 views

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 ...
YoavKlein's user avatar
  • 137
0 votes
2 answers
131 views

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 ...
S. M.'s user avatar
  • 398
0 votes
0 answers
15 views

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 ...
YoavKlein's user avatar
  • 137
0 votes
0 answers
22 views

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 ...
YoavKlein's user avatar
  • 137
3 votes
2 answers
135 views

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 ...
ESCM's user avatar
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0 votes
1 answer
62 views

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 ...
Minsky's user avatar
  • 115
1 vote
1 answer
185 views

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 ...
Colin Jack's user avatar
1 vote
2 answers
181 views

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 ...
masonCherry's user avatar
1 vote
4 answers
1k views

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 ...
zombiesauce's user avatar
0 votes
0 answers
19 views

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'...
Jack's user avatar
  • 1
17 votes
3 answers
5k views

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 ...
Floji's user avatar
  • 319
3 votes
2 answers
472 views

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 ...
infra's user avatar
  • 3,128
2 votes
5 answers
317 views

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 ...
Kamal S.'s user avatar
10 votes
3 answers
2k views

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 ...
Martin Dallinger's user avatar
0 votes
1 answer
280 views

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 ...
RandomAsker889's user avatar
2 votes
1 answer
7k views

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 ...
samshers's user avatar
  • 149
3 votes
2 answers
333 views

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 ...
Suraaj K S's user avatar
0 votes
0 answers
28 views

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 ...
newcomer-91's user avatar
0 votes
0 answers
89 views

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 ...
yaenu's user avatar
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1 vote
1 answer
51 views

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 ...
Atharwa Adawdakar's user avatar
1 vote
1 answer
218 views

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 ...
samshers's user avatar
  • 149
0 votes
1 answer
1k views

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 ...
Shehab White's user avatar
1 vote
1 answer
772 views

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 ...
ag07's user avatar
  • 111
0 votes
2 answers
387 views

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 ...
Muhammad Bilal's user avatar
0 votes
1 answer
177 views

What steps must be accomplished in each layer of the TCP/IP model to connect a website?

What steps must be accomplished in each layer of the TCP/IP model to connect a website?
ShooterLens Aim's user avatar