Questions tagged [ethernet]

For questions relating to Ethernet networking, as defined by the IEEE 802.3 standards.

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Creating a distributed ethernet using a single mode fiber ring

Can I create a distributed ethernet using just 1 x core of a single mode fiber ring ? This is an existing installation, I can't change the following constants: I have approx 100 locations (nodes) in ...
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17 views

Setting up a D Link Switch for PTP Passthrough [closed]

I have several devices which support PTP (Precise Time Protocol) and a D Link switch which connects all those devices. As far as I know, the switch I am using does not support PTP itself, but I was ...
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23 views

How does a host figure out the mac address owned by the address 239.255.255.250? [duplicate]

For example if I want to know the mac address for a machine in my local network, the host sends an arp request and eventually figures out the mac address of the local machine. But how does one know ...
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1answer
458 views

Can a radio share a MAC address with the ethernet interface of an access point?

I have a situation where I have found the BSSID to have a MAC address congruent to the MAC address of the ethernet interface. Is this possible? Does this happen with all access points?
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42 views

Robust Ethernet connection next to high power machines

We are creating a robot for facade treatment (cleaning, painting, drilling). I have few beginner level questions. An industrial robot with it's controller and our computer is placed at the top of a ...
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1answer
41 views

Carrier Ethernet - Implementation detail at the UNI needed

Metro Ethernet Forum (MEF) standard number 4 identifies two items of equipment - the UNI-C and UNI-N (UNI Client and UNI Network respectively) - on either side of the UNI. In so far as general terms ...
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3answers
4k views

Why does an Ethernet cable have four pairs?

I'm curious about why 10Base-T and then 100Base-T Ethernet networks used cables which had four pairs if they only needed two? Were there some cables that only had two pairs? If we wanted to increase ...
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1answer
46 views

If one of hub is damaged,will it cause others hub damage too?why can't i enable the rapid dual homing

There is a multi-ring topology,combined with 8 Hubs and 2 switches,i want to ask two questions 1. If H3 is damage,but the fiber is still ok,will H2 damage too in the future? i have a thinking to ...
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37 views

Is there a network cable tester device that tests the cables with realistic frequency instead of on/off leds?

I am not looking for a specific product recommendation. I am looking for a category of cable tester devices, so I can do a targeted search. I have an rj45 cable tester that tests the ethernet cables ...
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3answers
80 views

Terminology: Disentangling the word 'Ethernet'

I’m trying to disentangle the common usage of the word “Ethernet” I believe when people say 'Ethernet' they refers to 2 thing simultaneously: a Protocol a Transmission Line That is when someone says:...
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123 views

Is there a ping equivalent on layer 2?

You can use ping to measure RTT between you and an IP host and thereby confirm connectivity. Is there an equivalent that can be used on L2/Ethernet with MAC addresses? i.e. l2ping AA:BB:CC:DD:EE:FF (I ...
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131 views

According to appropriate standards, which Ethernet cable jacket colours should I use? [closed]

We have the following connections. User desks to patch panel to non-PoE switch CCTV to patch panel to PoE switch WiFi access point to Patch panel to PoE switch Floodlight to Patch panel to PoE switch ...
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25 views

Does creating frames done by device drivers?

If I got it right, TCP and IP packets are created normally by software running in the kernel. So when I as a user open up a socket of type TCP/IP and send a message, the kernel takes care of all those ...
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20 views

What is preamble in ethernet frame and why is it used? [duplicate]

I've searched all over the internet and every say that it synchronize the receiver clocks. What does that mean? Also I've seen another definition that preamble gives NIC time to realize a frame is ...
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52 views

Are ethernet connections trackable? [closed]

If I plug into the wall, is it track-able which room the ethernet connection is coming from? If possible, how?
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85 views

CSMA/CD: minimum frame size for Fast Ethernet and Gigabit Ethernet

In csma/cd the minimum frame size that should be transmitted in twice the propagation time for the standard Ethernet cable (10 base 2 or 10 base 5) . But how to maintain the same frame size for the ...
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1answer
41 views

Problems with cat 6 cable

Our company have all the networking with cat 5 cables. My problem is: one of our employees bought a cat 6 cable but we don't have any rj 45 for this cable, we only have for the cat 5. I tried so many ...
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1answer
45 views

Lan and baseband channel

We know the baseband line at one time send or receive data(half duplex). If more than one host send data at same time may occur collision. In bus topology see the same thing. Inspite this in home, ...
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1answer
31 views

How do i prevent dataloss, when installing an ethernet cable fairly close to an electric cable? [duplicate]

I want to install an ethernet cable and an electric cable (230V) right next to each other (same cable tube, currently 20mm in diameter, length up to 100m (i think its under 75m but i didn't measure ...
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2answers
99 views

What type of network cable is this and will CAT6 provide me any benefit over this?

I have a router configured as access point and connecting to the host router with four wire twisted pair cable which looks like below: I have some doubts regarding this: What type/sub type of this ...
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1answer
18 views

Achieving clock synchronization via 1588V2

Is it possible to achieve frequency synchronization between 2 network points (not TOD but actual frequency) - by using 1588V2 alone ? Or do we have to use SyncE for that ?
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36 views

Does bipolar encoding need a clock

if it does then when will a clock be useful in decoding bipolar signals 'I was thinking' it just see if it detects a -voltage & a +voltage and do "save " the bits accordingly
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9 views

Finding IP address [duplicate]

I have a device (logger for data acquisition), ut seems that someone has changed it's default IP address and lost it. I can't access it. Is there's a way to find it's IP?
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2answers
342 views

Can a bad ethernet cable cause lag spikes?

I needed to extend a 50m cable by about 1 meter. I know that the best solution would be to make a new run but it's very difficult to swap the cable so I tried to avoid it. As RJ45 couplers would take ...
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1answer
55 views

Exceeding SFP manufacturer maximum distance

What are the consequences of exceeding the SFP manufacturer maximum distance ? Example from Cisco, Table 2. SFP+ port cabling specifications of https://www.cisco.com/c/en/us/products/collateral/...
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50 views

Does 10BASE-T contain four wire pairs or two-wire pairs and why is it if it's four wire pairs?

As far as I know, 10BASE-T and 100BASE-T (types of UTP) use two pairs of wires, while 1000BASE-T has four pairs of wires. But when I look up the photo of 10BASE-T on google, it indeed contains four ...
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93 views

How is data flow in a twisted pair cable?

If i use a ethernet cable (twisted pair cable) in what form the data is flowing - digital or analog signal. And in pair 1 that is wire no 1,2 there is transmit+, transmit- respectively. how is pair 1 ...
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1answer
41 views

Did a "network hub" actually send and receive all data to every node? [duplicate]

In the early 2000s, I went to a store and bought a Netgear "network hub" either exactly this one, or extremely close to it: https://upload.wikimedia.org/wikipedia/commons/d/d9/...
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2answers
94 views

Can Ethernet frame be fragmented?

If there is IP fragmentation, is there also Ethernet fragmentation? I tried to google it but there seems to be no such thing. So what if, for example, we encapsulate Ethernet into ATM, what would the ...
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2answers
111 views

Losing connection when connecting a server to Stratix 5400?

I have a problem that when connecting a server to Stratix 5400 the Stratix loses connection for some seconds which causes a Safety Fault for the line because we have Safety PLC’s any help. ,Software ...
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7 views

PPP vs PPPOE vs Ethernet frame [duplicate]

PPP is a protocol that encapsulate data for point to point communication between 2 device that know mac address of each other ( I say they are in a scope that can see each other) why we need PPPOE and ...
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78 views

Does duplex depend on the cable or the interface?

I wanted to know what made a Duplex system work? I always thought it was the Switch that made it work. But I just read on my Cisco course 2 things that made me question it. It said this, and made me ...
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1answer
68 views

If SFP supports 4.25Gbps why don't they make a SFP RJ45 2.5Gbps module?

SFP transceivers support speeds up to 4.25Gbps, but SFP RJ45 only support 100/1000Mbps Why is there no support for 2.5Gbps RJ45? Is this a technical limitation or did no one ever decide to make SFP 2....
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1answer
44 views

Are there any advantages of using a crossover cable to directly connect modern devices?

Modern devices no longer need a crossover cable to directly connect via an ethernet cable. But are there any advantages of using a crossover cable anyway? For example, does a crossover cable decrease ...
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1answer
101 views

How is the maximum speed of an ethernet cable detected?

Let's say two hosts are connected with an Ethernet connection. There is a similar sounding question that talks about how the two LAN cards determine the link speed by sending and receiving auto-...
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Is Having a layer-2 broadcast domain cross long distances or multiple sites a bad idea? [duplicate]

Is it incorrect to have a layer-2 broadcast domain cross long distances or multiple sites?
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89 views

Geographic or Physical Limitations of VLANs

Is it incorrect to have a layer-2 broadcast domain cross long distances or multiple sites?
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41 views

Homeplug av frame

I want to check differences between a frame sent by a pc connected to an homeplug and one pc connected directly with the gateway/router. When i sniff packets i cannot see any differences in the frame, ...
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2answers
101 views

Detecting Ethernet over power by packets

If someone plugs an Ethernet over power (EOP, Homeplug) into the switch and then connect elsewhere in the building, can I detect this device by sniffing the packets with tools like Wireshark or ...
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22 views

Why do some Ethernet interface implementations fare better on cables with poor Near End Crosstalk and/or Return Loss performance than others do? [closed]

I'm conscious of the fact that this question may be open-ended which is discouraged per the How-to-ask guide, but I'm ignorant enough on the matter that I can't figure out how to ask a more pointed ...
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26 views

Could using punch-down blocks with long stripped ethernet cables cause signal loss or any other issue?

I see it on the internet where people strip and untwist their wires more than 10 cm to use with punch-down blocks. Won't this cause cross-talk or can other noises effect the signal when cables are ...
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3answers
348 views

Daisy chained ethernet: how to "tee" the loop without switch?

In this Schneider Electric white paper: Reduce Ethernet Connected Cost with Daisy Chain The author provides a daisy chain Ethernet topology in Figure 3: To connect the loop to another device (I'm ...
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1answer
42 views

Queuing delay model in ethernet switches

I am trying to model queuing delays in ethernet switches. Can anyone guide which queuing model can be used to model the queuing delays in a switch ?
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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 ...
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1answer
36 views

RJ 45 Ethernet cable for Industrial purpose [closed]

For an Industrial Solution, I have to use 8 Core cable more than 200 terminals to my device for maximum length of 4 to 8 meters. this for push button signal and switch indicators from micro control ...
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3answers
48 views

How does the network client pick a wifi signal, given two available frequencies?

This might be basic, but I don't know the answer... Given a router and a client, both having 2.4G (slower, more range) and 5.XG (faster, less range) frequency radios (and both named with the same SSID ...
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19 views

Is the exact endianness of an Ethernet Frame start with LSbit of Octet (MSByte)? [duplicate]

Following up this question: Confusions regarding byte and bit ordering of Ethernet Frame Just so I get the understanding correct, if I have a Destination address of the way we usually read MSByte/...
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2answers
123 views

Connecting two HP 2910al Switches using SFP to get 2Gb/s speed

I would like to Connect my two HP 2910al switches using SFPs to get a maximum of 2G links. is this possible, and how? I want to make both of them to use the IP address (ex 192.168.2.xxx). I have the ...
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24 views

Dynamic CAK, how MSK is derived at supplicant end?

For MACsec, dynamic CAK scenario using EAP-TLS, MSK at Authenticator is derived from Authentication-server as part of MPPE-Send-Key and MPPE-Recv-Key, which are used to further derive CAK/CKN. I am ...
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43 views

Should snmpIfHCInUcastPkts include packets bigger than 1522 bytes? [closed]

Packets bigger than 1522 bytes (as counted by Spirent Test Center) are being forwarded (bridged) but not counted in the following hardware counters on an Open Network Linux device: ifHCInUcastPkts ...

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