Questions tagged [ethernet]
For questions relating to Ethernet networking, as defined by the IEEE 802.3 standards.
705
questions
0
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1answer
23 views
Crossover Cabling - Reversing TX and RX Signals [duplicate]
It is often said that crossover cables 'reverse the transmit and receive signals' compared to straight through cables. However I am yet to see an actual explanation of why the reversal of signals is ...
3
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2answers
137 views
Industrial Ethernet network design
looking for some advice on network architecture for an industrial switchroom with several constraints.
Modbus TCP devices are located in motor control centre cells, these need to connect to the ...
0
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2answers
64 views
How does a Hub work when sending broadcast packages?
I know that hubs send broadcast packets, so every packets is received by each node in the broadcast domain. I read that frames that are received but that aren't addressed to a NIC'S MAC address are ...
1
vote
1answer
43 views
SFP to RJ45 for 10Gbit network
I am in the process of upgrading some of our network into 10Gb and grabbed the following:
A network switch by netgear, mode:GS110EMX
A bunch of assorted cat8 cables(for future proofing)
Two 10gtek ...
0
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2answers
50 views
Can / Is CSMA/CA used in wired network?
I learnt why CSMA/CD cannot be used in wireless protocols here. Here is what the answer says:
Wireless transceivers can't send and receive on the same channel at the same time, so they can't detect ...
0
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2answers
47 views
understanding fiber optics layers architecture
I'm studying the history and technical details about fiber optics and I'm having trouble understanding which are the different layers that exist and have been used over fiber optics.
For example, I ...
0
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1answer
37 views
GPON upstream frames capture
How capture GPON upstream traffic ?
Some professional tools exist: GPON doctor, GPON Xpert, displaying the GPON frames, etc, but is it possible to perform this task without using these tools ?
My ...
3
votes
1answer
96 views
Get the raw binary stream from an optical fiber
How get the raw binary stream from a fiber ?
Assuming we have a SFP (ethernet, FC, GPON, other), this transceiver is not protocol independant, and will treat and interpret the binary stream received ...
0
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2answers
78 views
What happens to undetected Ethernet errors?
The checksum used in Ethernet packets cannot 100% detect errors. If that is the case, how can I ensure that some file I have transferred from one computer to another is uncorrupted?
Thanks
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0answers
33 views
Which Ethernet Ring Protection Switching (ERPS) feature makes it so faster than RSTP/MSTP?
I want to know what makes it possible for ERPS to converge under 50 ms?
it's a hardware-specific feature that provides this fast convergence or it is about the much more efficient algorithm?
I read ...
1
vote
0answers
14 views
Forward traffic between 2 network interfaces in one Laptop [closed]
I have an ethernet module (a sensor but communicating via ethernet: TCP/IP) connecting to my laptop (x1 carbon). An android device (Pixel XL) in USB tethering mode connecting to my Laptop.
IP of ...
1
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1answer
90 views
Is PPP a useful choice for fiber connections?
I was recently thinking about how I would go about connecting two separate buildings using optical fiber cables. This is mostly for understanding how this would be done to further my mental horizon, ...
0
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1answer
40 views
Is it possible to propagate MAC address back to sender?
Let me first to tell me what I know, please correct me if I am wrong.
I know when Ethernet frame travels across the internet then Layer 3 data (Source and Destination IP) remains same and Layer 2 ...
0
votes
2answers
86 views
How is Ethernet a packet-switched network?
Let's say for example there is an Ethernet switch, and there are four PCs connected to this switch. PC1 and PC2 are communicating with each other, and at the same time PC3 and PC4 are also ...
0
votes
1answer
43 views
Is it possible to use a gigabit connection on 10/100 load balancer?
My ISP provides a connection output of 1000BASE-T.
I am trying to feed this to a load balancer device that only supports a 10/100 connection. However, the connection is not detected.
I am afraid this ...
1
vote
2answers
159 views
MSTP Ring - Maximum Number Of Switches?
We have inherited a ring topology with 12 switches configured with MSTP. Each switch is either 4 or 8 ports but in general most are 4 port with 2 fiber uplinks that form the ring.
We are getting a ...
0
votes
1answer
36 views
Inital value for the scrambler in 10GBASE-R
The standard says "There is no requirement on the initial value for the scrambler. The scrambler is run continuously on all payload bits".
I'm curious how the scrambled data can be recovered. To my ...
0
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0answers
37 views
Why wifi and ethernet use the same frame format from tcpdump -d output?
If I execute
tcpdump -i wlan0 tcp -d
or
tcpdump -i eth0 tcp -d
I get the same output
(000) ldh [12]
(001) jeq #0x86dd jt 2 jf 7
(002) ldb [20]
(003) jeq #0x6 ...
0
votes
1answer
73 views
Scaling fragment offset
I studied that fragment offset has 13 bits. At transport layer segmentation is done considering the the MTU at lower layers (network layer, data link layer). Ethernet format says the maximum data ...
0
votes
2answers
90 views
Can you stack Cisco 350 28P PoE switches with CAT5E or CAT6 ethernet cables?
I have four new Cisco SG 350 28P PoE switches, but no stacking cables. Can I use CAT5E or CAT6 ethernet cables to accomplish stacking them?
1
vote
2answers
33 views
Why do all leaf nodes in an E-Tree service belong in the same subnet?
I'm studying the CCNA R&S at the moment and I'm a bit confused about why E-Tree services require all leaf nodes to belong in the same subnet, despite the leaves only being able to send layer 2 ...
0
votes
2answers
77 views
Is Spanning Tree Protocol Needed?
If there are two switches connected directly together with two links is spanning tree protocol needed? please see below snippet
1
vote
1answer
555 views
Broadcast link vs. point-to-point links
What is the distinction between broadcast links and point-to-point links? In the paragraph below, the author switches between "broadcast link" and "broadcast network" which is causing my confusion..is ...
0
votes
2answers
51 views
Internet Entry Point
I am learning netwroking and would like to ask about how exactly we (as a casual user) get connected to internet and how a datacenter would do the same thing. i bet they dont use a regular modem which ...
0
votes
1answer
97 views
Sending TCP packet to the other device without connection
I think the sending packet to other device works like the following.
1. The server device listens with port. for example 80
2. The client connects to the server devices.
for example, the port of ...
1
vote
1answer
237 views
What exactly is fragment free switching?
Most commonly refered to as a compromise between store-and-forward and cut-through switching, this method involves storing the first 64 bytes of the ethernet frame in a buffer and then forwarding it. ...
0
votes
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 ...
0
votes
2answers
160 views
Confusions regarding byte and bit ordering of Ethernet Frame
I understand the concept of Endianess regarding numbers because there the bit significance is well defined. But when applied to things like Ethernet frame or Mac address, things are so clear to me, ...
22
votes
3answers
9k views
What is “industrial ethernet”?
When a teacher introduced it to us he gave the impression that it specifically covers some Siemens technology; that it's even a Siemens trademark.
I believe the term covers something more general, ...
0
votes
1answer
118 views
Weird Wireshark protocol list (eth:ethertype:ip:data where is the “udp”?)
I am capturing incoming and outgoing WAN to LAN data at a particular host on my LAN (i.e., the one actually receiving/sending the data). Sometimes I get anomalous captured frames that are missing the ...
0
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0answers
27 views
Wireshark logging same error on client and server
I did some testing in Socket Programming with JAVA and analyzed my traffic with wireshark. SetUp: 1 Server running a new ServerSocket(PORT) and 1 Client running a new Socket(IP, PORT). Server and ...
0
votes
1answer
31 views
How 2 devices with different speeds communicate [duplicate]
This is an extremely basic question, But I couldn't find any answer for that.
In the scenario which I have a very old compubter that transmits 10Mbits/s and a switch that has 100Mbits ports, how ...
2
votes
1answer
177 views
Cisco nexus 9396PX TX output discard on 40G interface without link congestion
We have cisco nexus 9396PX with N9K-M12PQ module (12x40G Interface), We have 8x10G L3 LACP bonded connectivity with our ISP and so far so good no issue at all. but recently we migrated that LACP LAg ...
0
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0answers
12 views
Is pair cable always full duplex? Can it be half duplex at double the bitrate? [duplicate]
This is probably a newb question, forgive me.
For pair cable, there are two signals that can be sent: following that logic, it seems like you could have two situations: full duplex at bit rate X in ...
0
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0answers
27 views
Expanding network to attached building
I own a electronic design company, and recently moved into a new office space. We currently are setup in the front office, location "1" on my image. We also are converting a warehouse into an assembly ...
7
votes
3answers
2k views
Why can a packet sniffer in an Ethernet LAN obtain all packets sent over the LAN?
Why can a packet sniffer in an Ethernet LAN obtain all packets sent over the LAN?
In a limited broadcast environment, such as in many Ethernet LANs, a packet sniffer can obtain all packets sent ...
1
vote
2answers
239 views
What all fields is the FCS/CRC in the trailer of the ethernet frame calculated over?
I am unable to find the correct answer to this question all over the web. Wikipedia states The FCS value is computed as a function of the protected MAC frame fields: source and destination address, ...
2
votes
1answer
118 views
Using an Ethernet cable and USB Ethernet adapter at the same time?
What would happen on using an Ethernet cable connected to one network and
then plugging in another Ethernet cable but using an USB Ethernet adapter from a
different network.
Would it connect to both ...
1
vote
2answers
125 views
RS_FEC OVERHEADS ON 25GBASE-R
I'd like to estimate the effective capacity of the 25 GbE link (25GBASE-R) to transfer an Ethernet payload of a particular size when Reed-Solomon RS(528,544) forward error correction (RS-FEC) is ...
0
votes
1answer
145 views
How does Kismet find WIRED devices when scanning Wi-Fi? [closed]
In an effort to better secure my Wi-Fi network by finding its weaknesses and mitigating them, I have employed the use of Kismet, a well known Wi-Fi security scanning tool. When I use Kismet to scan ...
2
votes
2answers
48 views
Circuitry for sending and receiving bit streams in networking
To my little knowledge , I know that digital signals are transferred over continuous EM signals . At the receiver end a bit 1 is detected when the amplitude crosses a certain threshold and a bit 0 is ...
0
votes
1answer
72 views
Is there a MTBF related to port linking?
During a firmware upgrade, I've noticed one problem: An equipment keeps linking/unlinking on a specific port of a PowerConnect 3548(stp portfast, switchport access mode). I've contacted the local ...
0
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0answers
31 views
Wago 750-377 - assign IP address
I've just bought a 750-377 wago fieldbus coupler and I'm trying to assign an IP address to it through an ethernet cable that goes from the device to my computer. Is there any way to do that or do I ...
0
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2answers
56 views
what does the flag and mtu means in here
Reading some logs from my system it states
eth0: flags 4163 < up, broadcast, running, multicast> mtu
I am not sure what is the meaning of the flag here
down below I see eth1,2,3 has the same flag ...
6
votes
8answers
4k views
What do the positive and negative (+/-) transmit and receive pins mean on Ethernet cables?
So I'm trying to understand the pin layout of an Ethernet port, specifically for 8P8C which to my understanding is the most common. Of the eight pins, only four are apparently used for communication, ...
0
votes
1answer
272 views
What is the use of Phy and MAC chip?
Is it mandatory to have a MAC and PHY chip?
Are these two chips within a NIC CARD?
As I understand, these two chips are connected using RGMII or SGMII or xaui.
13
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5answers
4k views
How exactly does an Ethernet collision happen in the cable, since nodes use different circuits for Tx and Rx?
I am trying to understand how a collision occurs in Ethernet, especially when a duplex mismatch exists or when on a legacy Ethernet network two nodes transmit simultaneously.
Everyone explains the ...
-1
votes
1answer
44 views
MAc address or IP address? which one gets used from my pc to router? [duplicate]
Question 1) which one is used nowadays? NAT or PAT?
Question 2) as I knew, when my pc requests some website, what happens is , the data(packets) from my pc go to router. then router makes the request ...
0
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0answers
12 views
What happens within a switch when a frame is moved from Device A on Switch 1 to Device B on Switch 2? [duplicate]
This might be a noob question but what happens within a switch (regarding mac tables) when a frame is moved from Device A on Switch 1 to Device B on Switch 2? I'm assuming the 2 switches are connected ...
0
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0answers
13 views
Ethernet Frame: Length Field and Transceiver [duplicate]
I saw the following description of an ethernet frame:
8 bytes: preamble & start-of-frame delimiter
Variable size data: 42-1500 bytes
– No length field: the transceiver grabs the ...
