Questions tagged [ethernet]

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

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18 views

Timing in Virtual Links for Ethernet

From my understanding, full duplexed switched ethernet networks provide determinism. However, the Bandwidth Allocation Gap does not define a time schedule 2 virtual links could have frames ...
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2answers
4k views

What's the difference between Ethernet link and Serial link?

Sometimes we see router connected use Ethernet link, sometimes use Serial link, what's the difference between them? and in what scenario we use them?
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2answers
593 views

PPP, Ethernet and PPPoE differences

Correct me if I'm wrong. So, Ethernet technology is being primarily used in LANs. And we use PPP in serial links. To carry IP datagram, we can use either layer 2 technology, such as Ethernet, or we ...
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1answer
51 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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5answers
35k views

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

Is there any specific calculation that that was done to arrive at this number, and what were the factors that were taken into consideration for that calculation.
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4answers
24k views

Ethernet device works on certain ports on Ethernet switch but not on others

I have a small and inexpensive ethernet switch which is giving me some headache. For some reason some devices only work when I plug them into specific ports. The ports are not broken, as other devices ...
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6answers
8k views

Why use IP if we already have a MAC address?

I am preparing for ICND1 exams and recently started to learn about different Cisco devices. I have just come to know how the packet is generated to be transmitted over a network, or outside the ...
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2answers
349 views

Why the network switch drop the frame acording to ethertype/length?

I have a network switch IC , and I am using to the send BPDU packet. I can send packet with 2 byte ethertype/length field like this : 81 00, 80 00, 91 00 and some special hex number. But if I try to ...
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1answer
55 views

Do Cisco SG300 switches perform CRC error correction?

Cisco SG300 series switches are capable of detecting CRC errors as can be seen in the interface counters. But can they correct CRC errors and pass the frame along to the destination or the only way ...
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5answers
2k views

How does a host in one subnet know to forward the packet to the router MAC, when trying to send a packet to another subnet

I am trying to understand the ARP protocol and I could not understand the above. Consider the topology as follows: H1(1.1.1.1) - (1.1.1.0)R(2.2.2.0) - H2(2.2.2.2) My understanding is that if the ...
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3answers
359 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 ...
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2answers
475 views

MTU the most Confusing Networking term. Lot of questions

I have ton of questions and i feel this is most confusing term for me. The more i read the confusion deepens. I am not able to connect dots. please help. Do we need MTU adjustment with EoMPLS/dot1q ...
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2answers
370 views

What is the benefit of sending some data uncoded in a 10GBASE-T PHY frame?

For 10GBASE-T / IEEE 802.3ae the Physical Coding Sublayer is extended with a low-density parity-check (LDPC) code. IEEE 802.3™-2012 55.1.3.1 Physical Coding Sublayer (PCS): The 3259 bits are ...
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1answer
93 views

How can 10Gbps travel over a 500mhz ethernet cable?

We recently discussed the Shannon-Harley theorem in class and compared the results between Ethernet cables to fiber optic given the same hypothetical SNR. However, it is not clear to me how you can ...
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1answer
40 views

Is it possible to upgrade a cisco 2600 series router to gigabit?

I'm new to working with networks and I have two cisco 2600 series routers (specifically 2610xm) which both have Fast Ethernet ports. I have configured these and been learning how to work with them ...
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2answers
1k 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. ...
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0answers
23 views

What is wrong with this CRC calculation? [duplicate]

I have gone through a few documents to understand how to check that an ethernet frame is valid. I do the following calculation, but I can see it is incorrect because it does not result in a crc value ...
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1answer
62 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 ...
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3answers
1k views

Unknown EtherType

I am parsing an ethernet dataframe. It has the form : (destination_mac_6_bytes) + (source_mac_6_bytes) + (ether_type_2_bytes). Usually, I see ethertype like Ox86dd (IPv6). But I came across this ...
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0answers
19 views

How to perform the CRC check for an ethernet frame [duplicate]

I have an Ethernet frame of n bytes, ending with 4 bytes that contains the Frame check sequence (32 bit CRC). What calculation do I have to perform to perform the check ? I looked on the algorithm ...
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3answers
162 views

What classifies as crossover cable?

The definitions I've read say that crossover cable is cabling which the receive and transmit pairs are swapped around. My question is based on the fact that beyond this, I've seen some diagrams which ...
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1answer
69 views

Transport layer segmentation and Ip layer fragmentation [duplicate]

From the OSI Model's point of view: If we already have Ip fragmentation which happen due to the network limitation, why the transport layer provides the segmentation mechanism via TCP protocol? why ...
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2answers
465 views

Is a datagram from an upper network layer converted 1:1 to one of the lower layer?

I know datagrams from upper layers are converted to those of lower layers by adding metadata, but I cannot seem to find this information anywhere. Which one of the below is correct? A single TCP ...
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5answers
15k 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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4answers
1k views

Why is the Ethernet Connection Symmetric?

I know that cable connection (DSL) is asymmetric, there is a certain bandwidth on the channel, and for a better user experience, they allocate a bigger portion to the downstream. I suppose Ethernet ...
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1answer
205 views

Why is default gateway in routers configuration usually set as an IP address?

I mean why not just: a MAC address? It should eliminate the need in ARP requests asking for gateway address. Also it should eliminate the need in changing IP addresses in settings when gateway IP is ...
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2answers
2k views

What is the reason for the different order of the Source and Destination in a L2 header?

A TCP/UDP header (Layer 4) lists the Source Port, then the Destination Port: An IP header (Layer 3) lists the Source IP, then the Destination IP: An Ethernet header (L2) and a WiFi Header (L2) lists ...
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1answer
77 views

Enterprise network VS Industrial network [closed]

I would like to know the difference between the enterprise network and industrial Network.If someone has experience in industrial network, is he able to work in enterprise network?
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1answer
61 views

Why is XGMII little endian while the network is in big endian?

Why is XGMII little endian while the network byte order is big endian (RFC1700)?
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1answer
197 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 ...
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2answers
145 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 ...
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2answers
161 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 ...
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1answer
68 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 ...
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2answers
305 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 ...
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2answers
78 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 ...
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1answer
106 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 ...
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1answer
102 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 ...
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2answers
2k views

Full Duplex and Collision Domain

I have a very basic query on Collision Domain and Full Duplex Mode. There are two types of logical topology: Ethernet and Token Ring . Whenever we read about Ethernet the first thing that we are ...
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3answers
10k views

Network Byte Order

According to big endian byte ordering or network byte order the bits are transmitted in this order: bits 0-7 first, then bits 8-15, then 16-23 and bits 24-31 last. Does this means that bits from ...
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2answers
89 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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1answer
109 views

Why doesn't Ethernet protocol support switch fabric topology?

While learning about Fibre Channel and SAN, I found the following information on IBM Knowledge Center: A switched fabric is a fibre channel topology in which individual node ports are ...
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4answers
11k views

Toggle Switch for an Ethernet Cable

Is it possible to place a switch in one of the four/five wires of an Ethernet cable that will disable it? For my hardware project I would like the user to be able to disable the internet connection at ...
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1answer
314 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, ...
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1answer
87 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 ...
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2answers
988 views

How many pps (64Byte each) i can receive in 1Gbps throughput modem / firewall

I need help with this: If i have 1Gb/s throughput. I can receive how many pps in 64Byte each packet / s? Let's say I can send (Packet / Second - 64Byte) 450,000, meaning I would not only have 230.4 ...
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2answers
184 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 ...
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3answers
248 views

What are the minimum requirements to be on the internet?

People often define the internet as a network of networks but this is wrong. If I connected two LANs together that wouldn't nesecarilly be on or part of the internet. In class we learned about ATM, ...
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1answer
55 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 ...
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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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2answers
111 views

Could long sequences of consecutive zeros cause Ethernet link problems?

I am in the process of debugging an Ethernet communication issue. Basically using Wireshark to monitor the source data the stream was intermittent when the cable was removed and subsequently ...

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