Questions tagged [networking]
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46
questions
0
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1answer
76 views
RJ-45 with only four wires?
Dig through a junk drawer, I find a long cable with RJ-45 on each end. Definitely not RJ-11. It has only four wires. What might it have been used for?
I'm not expert on wired ethernet, but in ...
0
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0answers
40 views
stm32F401re ethernet shield unable to associate IP address
I bought STM32 F401RE and Ethernet shield HR911105A with MCU W5100. I'm not able to configure simple connectivity with it. I have setup all SPI wires and simple code for setting up IP, subnet, and ...
1
vote
1answer
40 views
How to avoid duplicate messages in a mesh network of mcus
I'm working on a project, where each pcb has a connector on every side, so you can connect these board in a grid. It's basically a mesh network of modules.
These modules need to communicate with each ...
0
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0answers
10 views
finding the minimal length of a broadcasting frame in a channel(CSMA/CD)
i am unsure about this question. would appreciate your assistance with it.
in the following CSMA/CD network with cable length L and propagation T. assuming that the signal is not decreasing and there'...
-1
votes
1answer
53 views
Bit-Map vs ALOHA protocol
So i have been reading about ALOHA and Bit-Map protocols and i am note sure which is more preferable in the following scenario:
8 stations, numbered 0-7 want to transmit in any given time slot. ...
0
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1answer
58 views
Finding the overhead and distance of an unknown code based on message making algorithm
for an information word M with m bits that is coded as following:
M is coded into a word A using an unknown code that allows detection of not more than one error.
the code word is the word obtained ...
0
votes
1answer
39 views
THINNET 10BASE2 Network using RG-58 Coaxial Cable operating frequecy?
I am trying to figure out what the signal frequency of a 10BASE2 network is. Specifically the frequency of the signal being carried over coaxial cable. Data transfer is 10Mbps and the network adapters ...
0
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1answer
43 views
Connecting nodemcu through internet
I have a NodeMCU and a website (free website domain provided by hpage.com) and I have to send and receive some data (suppose a 8-bit number) from the website to the NodeMCU via internet.
The NodeMCU ...
0
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0answers
70 views
Why does 100G Ethernet use FEC while Infiniband doesn't?
The 100G Ethernet physical layer signalling is moving to PAM4 and using Forward Error Correction (FEC) when the lane signalling rate is greater than 25 Gigabaud (Either 4 lanes x 25 or 2 x 50).
...
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0answers
44 views
Do Broadcom's Ethernet chipsets need special software to operate?
I want to implement an Ethernet switch using Broadcom's chips. Are singing an NDA and getting the datasheets enough to work with the chips? I have heard that the chips must be programmed by a special ...
4
votes
2answers
830 views
Why are length-prefixed fields considered hardware unfriendly?
One criticism of GENEVE (a network encapsulation protocol) is that it uses tag-length-value fields, and these are hard to process in hardware.
Why is this considered hardware-unfriendly? What ...
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votes
3answers
241 views
Does the phone transmit waves? [closed]
In a cellular connection, How much is power density (in W/m2 or mW/cm2) of the RF energy from the phone to the tower? If not possible in above units then can I know in dbm ? My phone has:
Head SAR: ...
-1
votes
1answer
60 views
Choosing a networking protocol [closed]
I need several mbeds to communicate with a host PC, which will issue commands to individual mbeds. What would be a suitable networking protocol to achieve this? Bear in mind, an internet connection is ...
0
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1answer
37 views
Inter Device Expandable Network Protocol?
Currently I am working on a project where I need to install several peripheral devices in the network along with a master. This total system have some industrial application. I need to have the ...
2
votes
1answer
659 views
Generate hamming code-words with given minimum distance
My understanding of hamming code (adding this as it might help someone in future):
Description: Hamming code is basically an extended parity check code. Message is divided into blocks, and multiple ...
1
vote
1answer
540 views
What is problem with NRZ and how manchester line coding handles out of sync tx and rx clocks.?
I am reading about physical layer of the OSI model. Specifically the different ways in which digital bits can be represented as voltage levels, among the multiple types are:
NRZ.
Manchester encoding.
...
-2
votes
1answer
123 views
What can i use an oscilloscope for in terms of networking [closed]
as someone who is just getting their feet wet in networking (going for a+ cert currently and would like to go further,) ive noticed that oscilloscopes can be used to monitor... seemingly any ...
0
votes
1answer
113 views
Raspberry connected to adhoc and wifi simultaneously [closed]
Currently I am working on a project where we have to connect multiple cameras to a Raspberry.
Our idea is to buy multiple Raspberry PIs with a connected camera.
These raspberries connect to a ...
0
votes
1answer
51 views
How to implement Ad Hoc on Radio Frequency node? [closed]
i want to implement RF based network as indicated in below figure
Node is Basically Radio Frequency Transceiver i.e Si4432 interfaced with C8051 Micro controller . These nodes are simply Act as a ...
1
vote
0answers
82 views
XBee S2C DigiMesh Networking
I recently bought a Digi XBee S2C Development Kit. This is my first time with XBee radios and I'm working with DigiMesh as I will be using sleeping coordinators to make the entire network sleep.
I ...
1
vote
1answer
120 views
Can we do source transformation for dependent sources? [closed]
In network analysis, during source transformation for dependent sources
0
votes
2answers
372 views
How does data travel correctly over the wire?
I understand that through varying voltage, data can be transmitted as "high" and "low". What I don't wrap my head around is how the receiving end "dissect" the frame.
I know there is a concept of ...
2
votes
1answer
85 views
Unshielded RJ45 connectors on SFTP Cat5e
I have "inherited" an old SFTP Cat5e cable connecting the basement of my house to the upper floor. There seems to be a break on some of the wires (6 and 7) so it won't even function at 100mbps.
I ...
0
votes
1answer
58 views
Different phases on different components
Say I have a typical wiring in my room where in I have two computers (A and B). A is a ...
1
vote
0answers
73 views
Would forward error correction help?
I am working with a 433 Mhz transmitter for an arduino project. I found a Manchester encoding library on github(https://github.com/mchr3k/arduino-libs-manchester). It has checksums built in but the ...
0
votes
1answer
516 views
MCS 6 Transport Block size for 1 RB?
Edit: for some context
I'm working on an LTE project and was wondering if anyone more knowledgeable than I would be able to answer this question. Given the first table, we can see the relationship ...
1
vote
1answer
834 views
What do pull-up and pull-down resistors do in an ethernet PHY?
I've noticed that most ethernet physical layers (i.e. the interface between the MAC/network and e.g. an RJ45 connector with magnetics) have pull-up or pull-down resistors on the TX and RX lines. For ...
0
votes
2answers
2k views
Where is ESP8266 TCP/IP stack defined?
I just installed Micropython on my ESP8266 and realized that TCP/IP works fine with it. This made me realize I don't know where it's defined - options that came to my head are: 1) in Micropython code, ...
1
vote
1answer
68 views
How can 100Base-T achieve 100 meter distance at 125Mhz clock?
I admit I have some large holes in my understanding of this topic, but it seems like you run into physical limitations of the speed of light.
If the speed of electricity through copper is about 280,...
1
vote
1answer
92 views
very cheap bus communication network
Over Christmas I started thinking of putting together some nice lighting for the house. The main element I'm thinking of is a strip of LEDs that are individually addressable. The only ways I can think ...
0
votes
1answer
66 views
Device-to-device/machine-to-machine wifi IoT system — pushing message/action to a connected device
I am not sure if this is the best community for this question, but I couldn't find one dedicated to IoT. Or should I ask on StackOverflow?
I am looking to build the following IoT system using WiFi ...
2
votes
1answer
1k views
GMII/RGMII TX_ER signal: guaranteed functionality?
I have a question seeking to clarify EXACTLY what happens during a GMII exchange between MAC and PHY. Specifically, regarding the TX_ER signal.
IEEE 802.3 Section 3:
TX_ER is driven by the ...
3
votes
1answer
127 views
What punch down tool should I use on this ethernet jack?
As you can tell this does not have the vertical lines like a regular keystone jack. So i was wondering what punch down tool should i use? ...also what are these called?
1
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0answers
491 views
Broadcast traffic issue in PLC Ethernet network
The setting: network with about 10 PCs and 8 AB RSLogix 5000 PLCs.
The issue: Everything is communicating OK, but I'm seeing what appears to be a lot of broadcast traffic within the network. It is ...
0
votes
1answer
6k views
What is a flow table? Openflow
As question asks. What is a flow table? How is it different from forwarding table?
This link says:
Switching = forwarding by destination MAC
Routing = forwarding by destination IP
Forwarding = ...
2
votes
2answers
144 views
Ethernet surge and protection
I recently worked with a client who experienced a transient on their Ethernet cabling. As you can see, no actual PCs were damaged, only the Ethernet cards of some machines. We don't know where the ...
0
votes
1answer
921 views
Sending data over network via MicroController (Sparkfun Thing // ESP8266)
I'm getting frustrated and keep hitting a wall. My basic setup is I have an Apache server running on my Raspberry Pi and I am looking to send sensor data over the wireless network both are connected ...
0
votes
1answer
67 views
Operating multiple low power devices from 1 adapter [duplicate]
I have 3 WRT54G routers (12V), 1 voip gw (9V), 1 cable modem (9v) and a gbit ethernet switch (12v) which are all operating from their own adapters.
I planning to build a low power (probably 12V UPS) ...
0
votes
1answer
531 views
How does Frequency-division multiplexing deals with overlaps?
As I understand it, FDM uses separate frequency for each channel, thus A will transmit data, for instance, every two seconds and B every three seconds.
But, what will be delivered on the wire in the ...
0
votes
1answer
133 views
Mobile WIFI: how close can mobile devices be placed and still have a functional WIFI connection?
I wish to run a large array (50+) of hacked Android phones as a computing cluster. They will need to be networked so I plan to use their built-in WIFI radios to talk over a single WIFI network. (I ...
1
vote
2answers
86 views
How do car trackers communicate?
So i was thinking, How do car trackers or long distance (over 100kms) remote control communicate to their central commands,? Do they use the cell phone network? what could one require to set up such a ...
0
votes
1answer
1k views
Calculating attenuation of coax cable run
This question is related to my question about long-distance Ethernet.
I discovered the Netsys NH-310C, a reasonably-priced device for converting Ethernet to coax for long-distance runs. The ...
0
votes
1answer
73 views
What kind of failures can be explained by this fix?
My Dell PowerConnect 2324 is normally plugged in 24/7. At some point it stopped working (no connectivity, power light out) and I disconnected it from the network and power. Recently I opened it up and ...
3
votes
1answer
219 views
Weather Balloon Wireless Mesh Networking
I am trying to get real-time data feed from a homemade weather balloon radiosonde with the objective of sending HD video during the flight; this could be relevant for GoPro-ers who want to send their ...
0
votes
2answers
41 views
How is the capacity of link more for single network link
In networks
capacity_of_link = bandwidth*propagation_delay
My doubt is how can a same wire carry multiple signals? Is is because the wire is very long (still the wire can be either high or low). I ...
4
votes
2answers
867 views
On-Board connection of ethernet transceivers
Is it possible to connect two 1000-BaseT transceivers with each other? I have two transceivers, each of them has 4 twisted pairs that actually are meant to be connected to an RJ45 connector including ...
