Questions tagged [osi]

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

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94 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 ...
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1answer
42 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 ...
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1answer
41 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 ...
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0answers
14 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 ...
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0answers
20 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 ...
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1answer
224 views

OSI Model vs Network Model: Does It Matter Which One You Use?

The OSI (Open Systems Interconnection) model is comprised of the following layers: 7. Application Layer 6. Presentation Layer 5. Session Layer 4. Transport Layer 3. Network Layer 2. Data Link ...
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1answer
123 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 ...
3
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3answers
4k views

Where do the layers of the OSI Model operate in the operating system?

The OSI model describes them as layers. But where do these layers actually operate in the operating system? For example, where and what actually does TCP? All these layers are described as using ...
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2answers
36 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 ...
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1answer
22 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 ...
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1answer
44 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 ...
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7answers
15k views

OSI Model and Networking Protocols Relationship

When most networking students first learn about the OSI model, they spend a great deal of time trying to figure out which layer of the model a particular protocol fits into. We get a lot of questions ...
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2answers
40 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 ...
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4answers
95 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 ...
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0answers
18 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'...
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3answers
3k 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 ...
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1answer
50 views

Is NIC Layer 01 or Layer 2

Is NIC layer 01 or layer 02? I am asking this question because of I found both answers in different sources. Some-one says It is Layer 01. Someone says It is in layer 2. I am getting ready for ...
7
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2answers
13k views

Why PPTP, L2TP, PPPOE are in OSI Layer2?

PPTP, L2TP, PPPOE - these are tunneling protocols. And they are Data link Layer protocols. Why? As I understood, Layer2 protocols work only in same subnet. They don't use IP addresses and cannot be ...
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3answers
69 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 ...
6
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4answers
1k views

OSI layer of Neighbor Discovery Protocol

NDP operates using ICMPv6 and, even though ICMPv6 messages are encapsulated in payload field of IPv6 datagram, ICMPv6 and ICMP are usually considered as network layer protocols. At least, on Wikipedia ...
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0answers
13 views

OSI and TCP/IP models [duplicate]

my name is Alexander. I have problems with English, but I hope you will understand me anyway. I'm preparing for CCNA 200-301 and I have some problems with OSI model. Let me give you a little context. ...
10
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3answers
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 ...
8
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5answers
3k views

Why is the ICMP protocol considered to run at layer 3 on the Wikipedia page?

Why is the ICMP protocol considered to run at layer 3 on the Wikipedia page (same layer as IP) when the ICMP protocol data is a payload of the IP packet? This is the article on Wikipedia that states ...
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2answers
46 views

How to distinguish a traffic that belongs to specific service

Suppose I have a server running different services, say Email exchange, storage space, web server, and SQL database. Assuming this server is bounded with one IP address and one NIC card, how can I ...
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1answer
547 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 ...
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3answers
2k views

Does the OSI model support connectionless communication in the transport layer?

In section 7.4.4.1.2 of ISO/IEC 7498-1:1994(E) it begins with: In connectionless-mode, the Transport Layer provides the following functions to support connectionless-mode transmission: But many web ...
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1answer
163 views

Do I need to read standards to understand how networks work?

I am Computer and Communication Engineer, and I read many books about data communication and networking, all discussing basic concepts like OSI Model, topology in general, multiplexing, etc., but I ...
3
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2answers
84 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 ...
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2answers
647 views

Regarding clns mtu

I understand the below points,please confirm if my understanding is correct. MTU > MSS E.g if my MSS is 1460 bytes, then MTU should be at least 1500 bytes(20 bytes for IP header and 20 bytes for TCP ...
0
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1answer
392 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 ...
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0answers
19 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 ...
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0answers
36 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 ...
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4answers
197 views

What is the physical representation of the OSI model? [duplicate]

I read on the Internet that the NIC resides on the physical layer of the OSI model so what about the other 6 layers. I know what they actually do but i want to know how it's done. In other wards, what ...
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1answer
26 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 ...
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1answer
52 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 ...
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3answers
21k views

Do Bluetooth Devices have MAC address with the same specification as the MAC addresses of the Ethernet and Wi-Fi Network cards?

I recently found out that ZigBee devices have MAC addresses. ZigBee is more related to Bluetooth from what I know rather than Ethernet or Wi-Fi. Do Bluetooth devices such as phones, headphones, ...
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1answer
156 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 ...
0
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1answer
107 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?
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3answers
6k views

Maximum packet size Ethernet Frame and IP packet

I am a little bit confused about one fact. According to the specification, the ethernet frame maximum size is 1518 bytes, and the IPv4 packet size Length field in an IPv4 header can be up to 65535 ...
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2answers
99 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 ...
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2answers
11k views

VPNs are working in which layer of the OSI model? [closed]

As the following picture shows, it is possible to categorize VPNs in two general categories: Client-based VPNs Network-based VPNs When it is required to choose a VPN for implementation in a network, ...
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1answer
243 views

How does a 802.11 (wifi) frame identify the payload's layer 3 protocol?

My understanding is that the 802.11 frame header is an equivalent of ether header. In the ether header, there is an EtherType field that identifies the payload protocol, such as IPv4/IPv6/ARP etc. ...
6
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6answers
29k views

Difference between routing, forwarding, switching

I feel like the three terms are often used as synonyms but actually all mean something different. I did look at Wikipedia sites but I'm still unsure about the definitions of the three. From my ...
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1answer
337 views

Confusion about TCP/IP data flow in layers

I'm confused about how the data flows through the layers of the TCP/IP model, so I'll just tell what I think it happens (using an email example) and I'd appreciate if you can point my mistakes. ...
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0answers
27 views

What Invariants/guarantees do various layers of the OSI model provide? [duplicate]

I saw it stated in an answer to this other question What transmission service gurantees does Ethernet give? that every layer of the OSI model provides both "hard" and "soft" guarantees to the layer ...
0
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1answer
287 views

Transport layer segmentation and Ip layer fragmentation [duplicate]

From the OSI Model's point of view: If we already have Ip fragmentation which happen due to the network limitation, why the transport layer provides the segmentation mechanism via TCP protocol? why ...
3
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2answers
121 views

In IP, to what extent are the network addresses coordinates?

Routing of data relies on being able to reach the destination address. There are network addressing systems proposed where the addresses are coordinates, Vivaldi from MIT, for example. The routing in ...
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1answer
3k views

Logical Link Control (LLC) vs Medium Access Control (MAC)

What differs the LLC sublayer from the MAC sublayer? From what I've understood - The MAC sublayer does what the PHY layer should be doing: detection (error, collision), channel listening, analog-to-...
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1answer
651 views

Understanding EUI-64

I was reading Forouzan's book. It says following: In IPv4 addressing, there is not a specific relation between the hostid (at the IP level) and link-layer address (at the data-link layer) because ...
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3answers
1k views

Do routers understand transport protocol?

We are taught about the difference between hubs, switches, and routers. A hub is a layer 1 device, it only knows layer 1 and doesn't care about layer 2 and above. Similarly, a switch is a layer 2 ...