Questions tagged [ethernet]

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

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2answers
42 views

Pins #6 and #8 of my CAT6 ethernet cable are broken. Should I replace the entire cable or is it usable?

I wired up a ~40m long CAT6 cable following T568B pinout. According to my tester, pins #6 and #8 are not functional. I have re-wired both ends several times to make sure it's not my poor crimping; ...
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6answers
101k views

What's the difference between an Ethernet cable and a UTP cable?

Is there such a thing as an Ethernet cable or technically no? Are they actually called UTP cables? From wikipedia UTP cables are found in many Ethernet networks and telephone systems.
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1answer
56 views

What are the possible bottlenecks in this design?

I am currently finding myself in a position where I need to design a local network for parallel processing of large amounts of data from multiple sources. Unfortunately I lack the experience to ...
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2answers
492 views

In practice, how much can the 100m ethernet limit be pushed?

I am faced with putting an outdoor WiFi access point about 800 feet from the nearest building. There is no power at the far end. This will require a weatherproof AP that accepts PoE I've looked at ...
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1answer
125 views

What is the wireless bottleneck speed in my simple network map?

My simple Network topology Im trying to figure out what the maximum speed is in mbps on the blue and red links. The exact specs of the wireless networks are these: IEEE 802.11b/g/n, 2.4GHz Dual ...
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1answer
275 views

Noise Immunity - 1000BASE-T vs 100BASE-TX

Comparing 1000BASE-T and 100BASE-TX, given the same cabling and distance, in an environment with substantial electronic noise, theoretically, which of the two will be more resistant to noise?
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1answer
44 views

How Ethernet protocol is related to Ethernet types such 10BASE5?

I know that Ethernet is a Data Link Layer protocol which specifies how the communication takes place b/w nodes in LAN defined by standard IEEE 802.3. I came across a book in which there were different ...
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1answer
4k views

Why does 10Gbps ethernet claim PAM16 encoding then use a squared DSQ128 constellation?

I've been looking into the way that 10 Gbps Ethernet encodes its data and I'm a little confused by the nomenclature. I have gathered, e.g. from here http://www.ikn.no/download/Whitepaper-10G-...
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2answers
2k views

Does it work to use CAT6 cable between two CAT5 cables?

I have two Cat 5 cables pre-installed in the walls. I need to connect two rooms, each room has its own set of in-wall Cat 5 cables and a slots. Does it work to use a Cat 6 cable to connect the two ...
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1answer
40 views

How can I use two WiFi routers with one cable to the ISP router?

Let me explain... There is the fiber optic ISP router on the first floor, connected to it via LAN cable is a switch, connected to the switch via LAN cable is a WiFi router on the 7th. I want to add ...
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1answer
1k views

juniper vlan-ccc vs ethernet-ccc for eompls

In juniper ethernet-ccc transports customer's vlan end to end. Does vlan-ccc also transport customer's vlan across as well?
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2answers
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Does MAC replace CSMA/CD in Ethernet?

We now that in old days Ethernet use CSMA/CD for collision domain. However, with the advent of Switches now MAC addresses are used to identify the source and destination machine. But still when I read ...
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4answers
66k views

How does a switch learn a switch table?

Say the switch table is empty. If computer A sends a frame destined to computer B, the switch will broadcast asking who has the mac address of B. What if C suddenly sends a frame to A? What is the ...
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1answer
21 views

Gateway with multiple VLAN IPs on one NIC [closed]

I would like to separate several hosts from the local network and put them behind a firewall. I would like to use VLANs to "physically" separate them instead of using just different subnets. ...
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1answer
48 views

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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5answers
19k views

Is Ethernet port blinking really useful?

This question may not look as an important one and in fact it is just out of curiosity. But to the point: Is Ethernet port blinking really useful? Ethernet ports usually have two light indicators ...
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1answer
467 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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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
47 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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2answers
48 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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5answers
5k views

Why do we still use Ethernet?

There's no doubt the vast majority of Ethernet frames are transporting IP packets. I know there are various other protocols that can be transported over Ethernet as well, but those can be transported ...
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5answers
37k views

Why was the MTU size for ethernet frames calculated as 1500 bytes?

Why was ethernet MTU calculated as 1500 bytes? What specific calculation was done to arrive at 1500 byte ethernet MTUs, and what factors were considered for that calculation?
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2answers
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ARP Questions (Packet Types, Ethernet, Cache, Gratuitous)

Lately I have been doing some research on the Address Resolution Protocol, and even though I know the idea behind it I still have some questions. Q1: Are there more types of ARP messages that I am ...
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3answers
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What is an acceptable bit error ratio?

I recently got a job in IT infrastructure and terminating Cat5e is something relatively new to me. What is an acceptable bit error rate for 1 million packets? Here is a screenshot of a test I ...
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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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2answers
39k views

What purpose is the Uplink port in layman's terms and do I need it?

I have an old Linksys switch (EZXS55W) and it has worked fine for many years now, but I tried to hook something up today to the last open port and noticed the device didn't work when I did this. When ...
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3answers
83 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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1answer
47 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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1answer
6k views

Troubleshooting low Metro Ethernet TCP throughput

Background We rented a few layer 2 leased lines, i.e. you have one big pipe at the datacenter and the remote sites have smaller pipes. Inside the layer 2 network you can do whatever you like. Probably ...
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3answers
158 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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6answers
3k views

Do network adapters read incoming bits in a single stream?

When a Gigabit network adapter is receiving data, how is it receiving the bits? Is it seeing it all in one stream of 0's and 1's? Or is there somehow multiple streams of 0's and 1's coming in at the ...
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1answer
40 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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2answers
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What does the naming convention for Ethernet standards mean: 1000BASE-T, BASE-TX, BASE-SX, etc.? What is the meaning of the components of the name?

I understand the number in the naming convention. The number represents how many Megabits per second can the standard support. However, I do not understand the rest of the naming convention. What do "...
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1answer
136 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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1answer
98 views

Why must host A continue to transmit after host b sends runt frame post collision on ethernet? (CSMA/CD)

Trying to understand example from computer networks: a systems approach ... -Host A sends Host B a frame at time t; Packet arrives at B at time t + d; (d = one link latency) Instant before frame ...
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2answers
97k views

What is the actual size of an Ethernet MTU

I think I might be getting confused with terminology surrounding MTU. This definition from Wendell Odom's CCNA book on MTU: The IEEE 802.3 specification limits the data portion of the 802.3 frame to ...
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1answer
27 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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0answers
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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2answers
55 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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1answer
11k views

How can a TCP window size be allowed to be larger than the maximum size of an ethernet packet?

I know that TCP window sizes can be scaled to over 64KB, but looking at an ethernet packet datagram, such as this one: it looks like a layer 2 packet is limited in size to be much smaller than that. ...
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2answers
100 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
42 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
56 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
32 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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1answer
19 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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1answer
39 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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0answers
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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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3answers
2k views

How transparent bridging Wi-Fi with Ethernet works?

The way I understand (two-port) transparent bridging is that the bridge simply forwards packets to another segment on the network. But since the MAC address of the ethernet interface is different to ...
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2answers
495 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
61 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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