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Questions tagged [data-link-layer]

In the seven-layer OSI model of computer networking, the data link layer is layer 2. The data link layer is the protocol layer that transfers data between adjacent network nodes in a wide area network or between nodes on the same local area network segment.

From Wikipedia:

In the seven-layer OSI model of computer networking, the data link layer is layer 2; in the TCP/IP reference model, it is part of the link layer. The data link layer is the protocol layer that transfers data between adjacent network nodes in a wide area network or between nodes on the same local area network segment. The data link layer provides the functional and procedural means to transfer data between network entities and might provide the means to detect and possibly correct errors that may occur in the physical layer.

Resources

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What is cyclic redundancy check and how it works in simple terms (for-dummies style)?

I'm having trouble understanding the concept and workings of the ugly sounding term "cyclic redundancy check". I'm attending a college course on Computer Networks and I'm getting lost already. The trouble is that my understanding of mathematics is…
Boyko Arsov
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bit stuffing example

I'm going over an example that reads Bit Stuffing. Suppose the following bit string is received by the data link layer from the network layer: 01110111101111101111110. What is the resulting string after bit stuffing? Bold each bit that has been…
Celeritas
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Data Link Layer and Transport Layer

What is the need of error control at data link layer when Transport layer provides error control ? What is the difference between the two error controls ?
Utkarsh Srivastav
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OSI Layer 2 Network Programming

I've recently taken some classes in networking (CCNA 1 through 4), so I understand most of the theory behind it all. What I'd like to do now is take that knowledge I have and put it into practice in the form of some small applications. I've been…
daniel
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Why is the Frame Check Sequence at the end of an Ethernet frame and not somewhere else

An Ethernet Frame Check Sequence is always appended to the end of a frame in the Data Link Layer. Why is it appended to the end of the frame and not somewhere else? I thought about it and think it might have something to do with how e.g.…
Lukas_Skywalker
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What is the difference between the data link layer and link layer?

What is the difference between the data link layer and link layer? Do they mean the same thing?
Celeritas
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Error Detection Effiency (CRC, Checksum, etc)

I have a hypothetical situation of sending data units, each of a thousand bytes. Failure rate is rare but when a error does occur it is less likely to be a single bit error and more likely to be an error in a few bits in a row. At first I thought of…
irl_irl
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Single-bit Error Detection through CRC(Cyclic Redundancy Check)

I was going through some problems related to the single bit error detection based on the CRC generators and was trying to analyse which generator detect single-bit error and which don't. Suppose, If I have a CRC generator polynomial as x4 + x2. Now…
ankit
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How much of the network stack do I have access to using Node.js?

Looking at a representation of the TCP/IP stack, such as in this photo: I would be interested (just out of curiosity) to try and read the layer 2 (data link) headers. Is this possible? I think that the net module only gives access to the transport…
Zach Smith
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Proof of CRC Burst Error Detection Checksum Result

It is said that a CRC (Cyclic Redundancy Checksum) can detect burst errors of fewer than r + 1 bits, where r is the degree of the polynomial. Furthermore, a burst of length greater than r + 1 bits is detected with probability 1 – 2-r. Can someone…
anuja
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Parallel Crc-32 calculation Ethernet 10GE MAC

I have generated an Ethernet 10GE MAC design in VHDL. Now I am trying to implement CRC. I have a 64-bit parallel CRC-32 generator in VHDL. Specification: - Data bus is of 64-bits - Control bus is of 8-bits (which validates the data bytes) …
Tushar
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How to receive and deliver 802.11b/g data link (MAC) broadcast packets to Android applications

I was wondering whether I can receive broadcast packets at MAC level (L2-WiFi) on Android AND deliver such messages to my application which will parse the payload of such packets. The MAC interface parses all these packets by construction (e.g.,…
Alessandro Russo
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Diag output structure of Qualcomm modems

I have a Qualcomm Quectel EC25 modem which I can send AT-Commands to this module with reciving the response. I store this modem diag bytes using a python opensource app (qcsuper) with a little code manipulation. Here is a sample diag bytes: 21 00 00…
morteza ali ahmadi
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Capture diag frame data of Qualcomm Quectel modem using an open-source app in C++

I want to capture (and maybe dissect) the diag data obtained from Qualcomm Quectel modem (EC25) in linux. I have done this for mobile devices with Qualcomm chip-set in android environment using some opensource projects such as mobile-insight and…
morteza ali ahmadi
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Scapy: Is it possible to manually set the destination MAC address of ARP packets?

Using python with Scapy, I have no problems changing the MAC address destination of the packets using the following sample code: packet = Ether(dst=[MAC address])/IP()...... However, when I try to do the same with ARP like this: packet =…
Lew Wei Hao
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