Questions tagged [ethernet]
For questions relating to Ethernet networking, as defined by the IEEE 802.3 standards.
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How does a 802.11 (wifi) frame identify the payload's layer 3 protocol?
My understanding is that the 802.11 frame header is an equivalent of ether header. In the ether header, there is an EtherType field that identifies the payload protocol, such as IPv4/IPv6/ARP etc. ...
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Clarification on when routers encapsulate and decapsulate packets
I'm an application developer working on getting a working knowledge of network engineering, so basically a newbie. I've been trying to figure out exactly when routers decapsulate frames into packets ...
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setting up a VLAN and joining 2 buildings through underground cabling
I am pretty much a newbie when it comes to networks so forgive me in advance if this question seems odd.
So here's a situation I am trying to figure out. There's a company who operates in 2 adjacent ...
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Are optical Gigabit SFP modules backwards compatible with 100Base-Fx?
My FTTH connection is using an old CareLink CL-MC-W2B-20-100 optical converter. It is labelled:
10/100 Base-T to 100Base-Fx bi-direction/single fiber media converter
10/100M Single mode WDM 20Km ...
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Manually break ethernet frames [closed]
i have the next question: how can i manually create interference in fast ethernet cable or download the special program which will randomly corrupt ethernet frames (OS is not important)?
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Ethernet Link Status when when Autonegotitation is enabled
I'm trying to understand when a 10Base-T / 100Base-T Ethernet PHY device will signal a valid link, specifically by setting the Link Status bit in the Status register, in cases where autonegotiation is ...
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Switch Operation Beyond VLAN Segmentation
What are the other operations performed by a switch which are outside the VLAN's boundaries.
Is Logical (VLAN) Segregation is exactly same as breaking a switching network physically via a Router?
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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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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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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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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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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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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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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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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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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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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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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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Is there any difference between International and United States patch cable?
I'm looking to buy a Cat 8 patch cable. I found a cable that I like that meets ISO/IEC 11801 Class I and Class II but it is not compliant to TIA Cat8 (As defined in ANSI/TIA-568.2-D) which has ...
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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 ...
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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 ...
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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?
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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 ...
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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
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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 ...
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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 ...
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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 ...
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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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