Questions tagged [ethernet]

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

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9 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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How are IP datagrams transmitted from routers to AP to destination? [closed]

Assume two 802.11 wireless networks are connected to the rest of the Internet via a router as shown in the figure. The router has received an IP datagram with the destination IP address 24.12.7.1 and ...
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sniff tool for OSI layer1 [closed]

I have been using wireshark, which is good for debugging layer2 and above. Can anyone recommend a tool for debugging Layer1 or PHY? Does it need to be a logic analyzer with xMII protocol decoder?
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1answer
35 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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21 views

Internet speed being reduced over Ethernet [closed]

Alright, here is a weird one. Have AT&T Fiber (1gbps) for the house. Running a CAT5 from wall to desktop. When we first set it up (around two weeks ago), I tested the speed and clocked it at ~...
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8 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
79 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
38 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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1answer
37 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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1answer
46 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
36 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
70 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
56 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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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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3answers
53 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
61 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
40 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
73 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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14 views

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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1answer
83 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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1answer
26 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
83 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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0answers
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
146 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
33 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
35 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
44 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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16 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
88 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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18 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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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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62 views

Using GNS3 to Sniffing Packets on Siemens RuggedCom RS900

I am using GNS3 to simulate an environment. I have 4 docker containers which all host Python programs. Three of the devices communicate with each other via the programs (Program 1, Program 2, Program ...
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1answer
359 views

Alternatives to 802.11* wireless bridge?

Every now and then the question arises for me to link two Ethernet segments over some kind of outdoor wireless connection. It is usually over comparatively short distances (at some places maybe some ...
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1answer
64 views

GNS3 can not ping from ethernet interface to serial interface

So I am doing a Lab for one of my classes involving ipv6 and routing using EIGRP. When I set-up the network and assign the router interfaces with IPV6 address I get an issue pinging the whole network. ...
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1answer
82 views

Wireless, powerline or ethernet right next to electric cable

I need a new point of access to our existing network. We have power sockets but no Ethernet cable on the spot. I see three possible solutions to achieve this: Add a new WiFi6 router and connect it to ...
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1answer
75 views

Implementation of multi-lane ethernet

In multi-lane ethernet, are the lanes synchronized? i.e., if the symbol of byte 1 of a packet is sent in lane 1, the symbol of byte 2 of a packet is sent in lane 2, then symbol of byte 1 will be ...
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1answer
23 views

Transmission delay of multi-lane vs single-lane Ethenet

Suppose there are two devices that can transmit with same throughput (e.g., 10Gb/s). Suppose that one device is connected via single-lane cable while the other with multi-lanes (e.g., 8 lanes). Will ...
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2answers
84 views

Ethernet frame encapsulation - multiple

is it possible to encapsulate two Ethernet frame packets into one ether packet? My search seems to indicate that there is not a way to do this, unless one was using something like VPN packets, be ...
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1answer
62 views

In an IGMP V2 membership report message, isn't the destination Ethernet address based on the multicast group IP address?

Specifically, I think for this message type the Ethernet destination address always starts with 01:00:5E, followed by the second byte of the IP address masked with 0x7F, followed by the third and ...
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1answer
38 views

Routers FastEthernet interface clock autonegotiation protocol

In routers, for serial interfaces, we need to manually set the clock at the DCE router so that the ends of the connection can communicate. I know that in this way we are using time-division ...
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11 views

Query regarding ethernet header [duplicate]

I have a query regarding ethernet header. Some representation of ethernet header have Type Field and some tell it as Length field. Which is the right one here ?
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1answer
74 views

Is MII PHY RX_DV required to stay HIGH for entire ethernet frame?

Regarding MII spec, I have a question about the RX_DV signal that I'm not able to find elsewhere: From the perspective of the Ethernet MAC, when sending a frame to a PHY over MII, does the RX_DV (Data ...
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2answers
452 views

Static speed and duplex/no-negotiate causing input error

I noticed gradually increasing input errors for a FastEthernet interface which is connected to an end-user Windows PC. The default setting for all interfaces is no-negotiate. The Foundry switch will ...
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2answers
50 views

What if my data contains nothing but Preambles and Start of Frame numbers?

Will that continually reset the receiving NIC or is there a sort of escape character that need to be used if my data contains nothing but alternating 1s and 0s in 7 byte blocks with start of frame ...
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1answer
57 views

Ethernet Frame visualization

One IP packet is fragmented in multiple ethernet frames at sender's side And at receiver's end, all the frames are combined to get back the IP packet So is there any way to see what payload each ...
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1answer
25 views

Can we use NLP/Autonegotiation to sync clock instead of preamble?

since both NLP/FLP and preamble are using predefined pulses, can we use autonegotiation as a way of sync clock, so we don't need preamble anymore?
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1answer
177 views

RSTP sending BPDUs out of the network switch?

I need some information about RSTP If the port state is blocking, discarding alternate . Should BPDU be sent to external ports? I cant see any BPDU in wireshark if the port states Alternate,Discarding ...
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2answers
180 views

How to detect start of FCS in an Ethernet Frame

I was reading about the Ethernet frame and its various fields, I noticed that the data (payload) field can be variable and is followed by a FCS field for detecting bit errors. If the payload is ...

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