Questions tagged [ethernet]
For questions relating to Ethernet networking, as defined by the IEEE 802.3 standards.
717
questions
0
votes
2answers
41 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 ...
0
votes
1answer
42 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 ...
0
votes
0answers
13 views
what does the outer conductor in coaxial cable work? [closed]
outer conductor in coaxial cable, absorb outer magnetic field or provided electromagnetic field to protect the inner conductor which carry the data signals
2
votes
2answers
300 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 ...
0
votes
1answer
26 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 ...
4
votes
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 ...
1
vote
2answers
285 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 ...
0
votes
1answer
72 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 ...
1
vote
1answer
35 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 ...
0
votes
0answers
18 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 ...
0
votes
0answers
13 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 ...
5
votes
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 ...
0
votes
1answer
47 views
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 ...
0
votes
1answer
37 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 ...
0
votes
1answer
200 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 ...
0
votes
1answer
43 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 ...
4
votes
2answers
446 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 ...
0
votes
1answer
36 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?
1
vote
1answer
53 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)?
0
votes
1answer
43 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 ...
3
votes
2answers
144 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 ...
0
votes
2answers
121 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 ...
1
vote
1answer
53 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 ...
0
votes
2answers
81 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 ...
0
votes
2answers
56 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 ...
0
votes
1answer
55 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 ...
3
votes
1answer
97 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 ...
0
votes
2answers
83 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
1
vote
1answer
144 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, ...
0
votes
1answer
48 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 ...
0
votes
2answers
112 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 ...
0
votes
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 ...
1
vote
3answers
239 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 ...
0
votes
1answer
43 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 ...
0
votes
0answers
41 views
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 ...
0
votes
1answer
95 views
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 ...
1
vote
2answers
146 views
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?
1
vote
2answers
47 views
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 ...
0
votes
2answers
82 views
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
1
vote
1answer
1k views
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 ...
0
votes
2answers
72 views
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 ...
0
votes
1answer
138 views
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 ...
1
vote
2answers
596 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. ...
0
votes
2answers
208 views
Which physical layers are part of PROFINET?
I understand that Profinet builds on Ethernet, but I am not quite sure how.
Ethernet has a lot of different standards for the physical layer, eg 10Base2 (coaxial, 10 Mbit/s), 100Base-TX (twisted ...
0
votes
2answers
336 views
Confusions regarding byte and bit ordering of Ethernet Frame
I understand the concept of Endianess regarding numbers because there the bit significance is well defined. But when applied to things like Ethernet frame or Mac address, things are so clear to me, ...
22
votes
3answers
9k views
What is “industrial ethernet”?
When a teacher introduced it to us he gave the impression that it specifically covers some Siemens technology; that it's even a Siemens trademark.
I believe the term covers something more general, ...
0
votes
1answer
179 views
Weird Wireshark protocol list (eth:ethertype:ip:data where is the “udp”?)
I am capturing incoming and outgoing WAN to LAN data at a particular host on my LAN (i.e., the one actually receiving/sending the data). Sometimes I get anomalous captured frames that are missing the ...
2
votes
1answer
229 views
Cisco nexus 9396PX TX output discard on 40G interface without link congestion
We have cisco nexus 9396PX with N9K-M12PQ module (12x40G Interface), We have 8x10G L3 LACP bonded connectivity with our ISP and so far so good no issue at all. but recently we migrated that LACP LAg ...
7
votes
3answers
3k views
Why can a packet sniffer in an Ethernet LAN obtain all packets sent over the LAN?
Why can a packet sniffer in an Ethernet LAN obtain all packets sent over the LAN?
In a limited broadcast environment, such as in many Ethernet LANs, a packet sniffer can obtain all packets sent ...
1
vote
2answers
440 views
What all fields is the FCS/CRC in the trailer of the ethernet frame calculated over?
I am unable to find the correct answer to this question all over the web. Wikipedia states The FCS value is computed as a function of the protected MAC frame fields: source and destination address, ...
