Questions tagged [osi]

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

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MAC vs Local IP [duplicate]

As far as i've understood the datalink layer (level 2) of the ISO/OSI stack is responsible for local networks and it uses MAC addresses to establish connections between nodes. Also, local ip allow ...
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1answer
37 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
45 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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2answers
111 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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0answers
16 views

how OSI and TCP/IP layers work? [duplicate]

I am really confused by how the layers these model work. I'm not asking about what are their functions. I read that transport layer provides end-to-end of all packet delivery, and networking also ...
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3answers
115 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 ...
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2answers
146 views

Which physical layers are part of PROFINET?

I understand that Profinet builds on Ethernet, but I am not quite sure how. Ethernet has a lot of different standards for the physical layer, eg 10Base2 (coaxial, 10 Mbit/s), 100Base-TX (twisted ...
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2answers
673 views

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

How many types of VPN is out there and in which layer of the OSI model are they working?
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15 views

Why are large networks unable to rely solely on the use of physical addressing? [duplicate]

First of all, I would just like to point out just how new I am to the subject of computer networking. Therefore, I apologise if my question seems a poor one however I am currently unable to find an ...
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1answer
27 views

Whats the security difference between Policy Based IPSec VPN tunnel vs HTTPS + Basic auth

We have several customers with the same service installed within their DMZ. This service is a HTTPS server. The server does not have authentication, this is solved by configuring the NetScaler ...
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1answer
159 views

What's the meaning of `circuit level gateway`?

The proxy server is an important security function provided by the Internet "circuit level gateway". Its work is mainly at the session layer of the Open Systems Interconnection (OSI) model, which acts ...
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28 views

what protocols does EAP AKA use?

can someone please explain me what protocols does EAP AKA use with respect to the OSI model? (for example what protocol it uses in data link layer and what protocol in transport layer)
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2answers
40 views

LLC connections

TCP establishes a logical connection before sending data,where LLC connections are physical and are being held just between two computers,not more. Is this correct? If so,why LLC=LOGICAL LINK ...
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1answer
37 views

why can't we use the sequence number to distinguish them since every packet has a different sequence number? [closed]

It is a question from Networking stanford course. A server typically listens for TCP connections on a particular port (e.g. 80 for HTTP or 22 for SSH). Which fields can the server use to ...
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93 views

Which fields can the server use to distinguish packets for a particular client connection? [duplicate]

A server typically listens for TCP connections on a particular port (e.g. 80 for HTTP or 22 for SSH). Which fields can the server use to distinguish packets for a particular client connection?It is a ...
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2answers
837 views

At which OSI layer a user-generated data resides?

I am getting a bit confused about which OSI layer is being used to store user-generated data. As far as I understand the process of encapsulation, the higher layers (starting with layer 7 - ...
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3answers
244 views

How to explain the data flow of OSI model layers in a single picture [duplicate]

Take an example of searching www.example.com in a web browser. I have some confusions at each layer and they are We have opened a web browser and searched for www.example.com. Now, As far as I know, ...
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2answers
313 views

Do the concepts of IP address and network interface not belong to the same layer?

https://unix.stackexchange.com/a/508065/674 You are confusing the device driver layers and the IP layers of the stack. At the IP layer, 127.0.0.1 is just another IP address and treated the ...
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1answer
95 views

Message formatting and encapsulation

I've gotten confused when reading about encapsulation and the OSI and TCP/IP models. I first read about message formatting and encapsulation and the diagram I read showed: Destination | Source and ...
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1answer
90 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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8answers
2k views

Using sound waves in layer 1

Is it possible, in theory, to use sound waves as the physical medium to transmit data over a network? In other words, could you implement layer 1 of the OSI networking model using sound waves or am ...
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4answers
835 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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1answer
51 views

Abstract service primitive

In SNMP RFC documents, often the concept of abstract service primitive (ASP) is used. What is ASP in fact ? I think it is also used in ISO OSI.
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3answers
972 views

Session layer vs Transport layer

It seems both do the same thing (or establishing a session between two hosts differs from establishing a connection between two?) So what exactly is the difference here that make us consider them as ...
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2answers
69 views

Do protocols ever have standards that affect multiple layers of networking?

I'm reading about higher-level protocols such as HTTP and SOAP (concerning the application layer at the highest level) in addition to lower-level ones such as TCP. So far these protocols concern only ...
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1answer
100 views

Where does DNS resolution fit within the TCP/IP stack?

I know that it's possible to whitelist/blacklist IP addresses (for example, only allowing a few external IP addresses to be contacted from within a VPN). But since IP address destinations are the ...
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1answer
336 views

Dependency between IEEE 802 and OSI model [duplicate]

My question is focussed on IEEE 802.11x for (WLAN) and 802.15.1 (Bluetooth) Wikipedia and other sources underline, that the mentioned IEEE standards just define the PHY and MAC layer from the OSI ...
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1answer
1k views

Data link layer acknowledgement

I'm confused with some concepts please help me out, Data link layer manage flow control hop to hop. Flow control requires acknowledgement receiving but If we observe data link layer header, it does ...
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1answer
35 views

Are there any network devices that can be configured to add information from one layer to another?

If I have a corporate network, no WWW Internet outside of it, only different subnets. Can a Cisco router or switch be configured to take information from one layer and embed it in another layer? For ...
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3answers
116 views

What is the physical representation of the OSI model?

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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3answers
345 views

Do OSI and TCP/IP models use the same protocols?

OSI is known for using hundreds of protocols to do its job. Both OSI and TCP/IP have Transport and Network(Internet) layers where TCP and IP protocols work respectively. It is clear that TCP/IP model ...
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1answer
44 views

How to add new tasks to layers of OSI or TCP/IP?

Which software and hardware parts of a computer are responsible for adding or removing values to the initial payload of a data packet in every layer of OSI or TCP/IP model? In other words, which parts ...
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3answers
4k views

Is the addressing done at transport layer or network layer of OSI?

According to the OSI model, the transport layer divides the data into segments and then attaches the source IP and destination IP along with the port numbers. Also it is said that the network layer ...
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2answers
84 views

what are multiple formats of message when passed through all the TCP/IP layers

I was wondering how the message changes its form or structure while passing through multiple layers. Consider host 'A' sending "Hello" as message to host 'B'. So how it changes its form while ...
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1answer
319 views

How is Network Access Layer/Link Layer of TCP/IP model different from Layer 1 and Layer 2 of OSI?

I was reading CCNA R&S book by Todd Lammle, I saw this in the chapter TCP/IP Basics under Network Access/Link Layer Advantage of this layer over Layer 1 and Layer 2 of OSI model is that there ...
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6answers
2k views

Why do we need FTP when there are layers to transmit data?

In OSI, there are layers for routing, encapsulating and transmitting the data. Then why do we need FTP? I read the following definition of FTP in books: FTP is used for transferring files on ...
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3answers
2k views

Error Detection across OSI layers confusion

Confusion: How does the transmitter know that his information( bits in physical layer, frames in data link layer, packet in network layer ) was transmitted correctly to the receiver? I know that in ...
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1answer
96 views

What requirements must general firewall/routing software meet, to make OSI 2 port mirroring work correctly?

The basics are obvious, but there are technical points of networking implication which I don't understand. Some of these are general to networking, others general to all routing/firewall softwares ...
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2answers
3k views

What is the difference between TCP/IP protocol and TCP model?

We know that there are two models OSI and TCP model. But TCP/IP protocol is different from TCP model as this protocol used in both OSI as well as TCP model. So why the two are named the same is ...
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3answers
1k views

Does the OSI model support connectionless communication in the transport layer? [closed]

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 ...
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1answer
1k views

OSI model peer communication

"In OSI model, each layer provides a protocol to communicate with its peer. When a packet is transmitted by a layer, a header consisting of Protocol Control Information (PCI) is added to the data to ...
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2answers
223 views

Why Ethernet was chosen to be the primary protocol + why carrier ethernet was created?

I'm currently trying to investigate the extra benefit that Ethernet has to offer for the internet today. As far as i investigated & know, Ethernet gives us a new hardware, cables and functionality ...
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1answer
2k views

Does the physical layer is OSI ISO model add any header?

According to OSI model, does the physical layer add any header to the date it receives from layer 2? Or is it simply sending the data frames it gets from layer2 as shown in the figure below? Are the ...
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1answer
59 views

What are connectivity associations in LAN? - IEEE Std 802.1X-2010

In IEEE Std 802.1X-2010, Appendix D, Section D.8, there is the following phrase However simple or complex, the establishment of a connectivity association for connectionless data transfer ...
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2answers
575 views

OSI and TCP/IP: which is the relation? [duplicate]

In the "network" literature there are always explanations of this two reference models: OSI and TCP/IP. The TCP/IP conceptual model is indeed a "fact" in terms of implementation. Anyone can find the ...
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2answers
1k views

Packet filtering firewall

I read that packet filtering firewall operates at level 3 (network layer). In the description I read that it filters packets based on IP addresses and ports. If it's operating at level 3, how can it ...
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1answer
44 views

How will these frames be delivered to respective destination nodes? [closed]

I have the following 3 devices on my network(a bus topology): A,B,C Let MAC(i) - denote the MAC address of the device i. IP(i) - denote the IP address of the device i. The devices B and C happen ...
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1answer
117 views

In the MAC acronym what do the words Media, Access and Control refer to independently?

I am not a native English speaker and I know what MAC addresses are and how are they used in networks. However what I do not understand is where this words came from independently. What does Media ...
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1answer
44 views

Placing a “protocol” field in the IP header breaks the conceptual separation of interests that the OSI aimed for [closed]

I saw that while reading an answer about .. and now I'm confused.
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1answer
435 views

How does a NIC know where the start of a frame is?

A question popped into my head today and after a quick few searches on google, I have no idea. When a device is sent a frame there is a layer 1 header/preamble saying the length and layer 2 protocol (...