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Questions tagged [ethernet]

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

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How to connect IP network to outbuilding [on hold]

At my lakehome I have a great Internet connection with both wired and wireless devices. And I also have a garage some distance from the house that I want to build an office into with a wired ...
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22 views

Practical limits of shielded Ethernet cable

If I run S/FTP Ethernet cable ran next to 120V conductors (inside 3/4" conduit) for about 70 ft. is there chance that I'll have a usable data connection? I'm fully aware that this is a terrible way to ...
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Local network is seeing high TTFB stats on website

Recently we noticed that whenever you hit our companies website from inside our offices we get a TTFB (Time to first byte) of 8-11 seconds. If I hit the same site via remote access on my machine at ...
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6 views

why would a LAN transfer go slower when router is connected to network [on hold]

Before I ask, I realize the different hardware might be at play but I did some other tests that make me think its not the hardware and I wanted to ask to see if maybe there is something else going on. ...
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1answer
207 views

Lost Ethertype in encrypted MACsec frames

MACsec uses an Ethertype of 88E5. This presents an obvious problem when encrypting frames which already have, or should have, another Ethertype. This RedHat blog, for example, states "[MACsec] can ...
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1answer
23 views

Where I can find frame specification?

When I capture from wireshark traffic I can see data like this Where I can see the specification of each field? When I read wiki https://en.wikipedia.org/wiki/Ethernet_frame there is nothing like ...
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2answers
55 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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1answer
29 views

Half duplex setting switch forwarding frame collides with host forwarding frame

So my question is regarding half duplex switches connected to hosts. Consider a case where a switch is connected to a host by a single link. In an event where a switch decides to forward a frame to ...
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1answer
35 views

VMware Ethernet connection to two different switches that are linked together - What can result? [on hold]

I have a client that someone in the past setup two NICs on the server to be active on vSwitch0. vSwitch0 has load balancing set for Route based on originating virtual port. Switches are D-Link DGS-...
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1answer
48 views

Does MACsec (IEEE 802.1AE) support multicast / broadcast?

In general, Ethernet supports both multicast and broadcast. However, once you start encrypting the payload, you need a key management. I am wondering if IEEE 802.1AE supports multicast and broadcast? ...
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1answer
27 views

Why do I see “ethernet” keyword in my wlan0? [closed]

When I check my wireless network card interface with the command ifconfig wlan0: ether -my-mac-adress- (Ethernet) I just started to learn this stuff, but I thought Wifi and Ethernet are kind of ...
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2answers
63 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, in which 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 ...
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1answer
31 views

How to avoid microbursts causing drops?

I have a network issue that has to do with microbursts. I will first tell a bit about the network: There are 4 Aruba/HP ProCurve switches. 1 Core switch and 3 downstream switches. All connections in ...
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3answers
81 views

Ping command through network

I have been trying to understand how and what tables are populated ( if they are clean at the start) when a ping command goes through. Lets say I have this network: I want to send a ping command from ...
7
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1answer
138 views

Run MACsec and VLAN in parallel?

MACsec (IEEE 802.1ae) adds a security tag to an Ethernet frame and encrypts the IEEE 802.1Q field, the EtherType and the payload field. If you want to use VLAN, you need the 802.1Q field to announce ...
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3answers
49 views

Two ports both in VLAN 1 on two separate switches down/down

For someone who recently got their CCENT, I feel kind of stumped. I have two switches, both are Cisco 3550s. I am using VLAN 1 as a management vlan and on S1, I assigned IP address 10.24.0.11/24 to ...
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1answer
37 views

Coexistence of different automation protocols in a single application

I was searching for suitable Modbus hardware (we have some already installed) for point-to-point communication via existing network, I came across new EtherCAT one. So wonder if different protocols ...
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1answer
53 views

Advice for a small school IT lab migration [on hold]

I'v been referred to a new client (small school) to 1)Move their file server (x1) to a dedicated room & 2)move their IT lab (25x workstations ; 2 dumb switches) Preface: Client has had no ongoing ...
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1answer
1k 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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3answers
83 views

How did one go from IP to MAC in classful networks?

This is more of a question asked out of curiosity than for practical reasons, but it's bugging me, because it might point to a lack of understanding elsewhere. Back when classful IP addresses were ...
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3answers
403 views

How to debug L1 Auto negotiation issues?

One of our Linux hosts has started switching its gears recently. While checking the interface speed, I could see that the interface has switched down to 10Mbps. The NIC and Switch are capable of 1G ...
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5answers
2k 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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3answers
58 views

How can 1000BaseT transmit on Rx & receive on Tx pins?

How can 1000-BaseT (Gigabit ethernet twisted copper pairs) technology transmit over the Rx pins & receive over the Tx pins? It's baseband technology (hence the name), right? Discrete digital ...
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1answer
209 views

Data link layer acknowledgement

I'm confused with some concepts please help me out, Data link layer manage flow control hop to hop. Flow control requires acknowledgement receiving but If we observe data link layer header, it does ...
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2answers
109 views

Accessing Internet without WIFI or Ethernet

Theoretically, is it possible to access the internet through a browser without connecting to an ethernet cable or using WIFI?
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1answer
77 views

How does a device differentiate between a router interface and switch interface [closed]

We have a device in work, in the manual it says connect via a switch. Obviously it works fine with any other device, once it is connected via a switch. But say in a topology, it could be directly ...
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1answer
57 views

What is physically different between 10base-t and 100base-t?

I would assume that the primary difference between 10base-t vs 100base-t is the speed of the clocks interpreting the electrical signal. In other words, if you ensure that a "bit" is transmitted in 1 ...
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2answers
890 views

Ethernet padding value

When the data sent in an Ethernet frame is less than 46 bytes, extra padding needs to be added to the payload. The question is: Which is the value of that Ethernet padding? I'm asking since in real ...
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1answer
41 views

Feeding a PoE capable device with variable power supply over TIA568 A cable (DC spares)

The purpose of such a variable power over Ethernet supply would be to test network equipment that are receiving power over PoE under condition of conditions of low voltage or current and determining ...
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0answers
42 views

How to design network with high availability in a multilevel small workplace [closed]

I want to create a network in my work 4 floors 50m2*4 workplace. Requirements are simple: Share internet ( < 20mb/s ADSL) while blocking someone from abusing download speed for long period. (...
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1answer
26 views

Can QSFP28 (aka zQSFP) DACs be used in place of QSFP+ DACs for 40GBase-CR4 Applications?

All: Have an testbed configuration where we're running 24 servers with Intel XL710DA1 40G NIC into a switch with 40/100G ports. Trying to use DACs to hold the cost down, but parsing the specs for ...
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1answer
34 views

For ethernet with bandwidth B, how much time a node has to wait before sensing the channel after the first collision detected?

Let's say one node detected a collision at t=0, in B Mbps ethernet, how long will that node wait before sensing the channel again?
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2answers
85 views

Determine whether the MAC address is of a router or the destination computer?

In a given Ethernet frame containing the HTTP GET message can we tell apart whether the MAC address of the destination is of a router or end host? The link to ethernet-ethereal trace :: https://drive....
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2answers
80 views

How to compute the round trip delay [closed]

I have a query on how to compute round trip delay. I know it is 2 times the propagation time, but let's say I have a packet of 100 bits and a transmission speed of 2 Gbit/sec, how do I compute the ...
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1answer
31 views

Unconnected cable in a switch

A cable plugged into a switch but unconnected on the other end, might lead to any problem in a "noisy" environment (industrial)? It's short, 50 cm, but there are motors, inverters, power supplies ...
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2answers
115 views

What are the reasons for ADSL to use ATM instead of Ethernet

I'm a newbie to networking and I wonder what are the reasons for ADSL to use ATM instead of Ethernet ?
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1answer
37 views

What is meant by “technology dependent” PHYs? [closed]

Is there something like "technology independent" PHYs? To add the context as Zac67 correctly mentioned, I was reading clause 73 of 802.3-2015. 73.3 - Functional specifications. Excerpt: "The Auto-...
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3answers
73 views

Why do we need an ethernet MAC address? [duplicate]

Don't think it's a duplicate. I've searched really many articles and couldn't find the satisfying answer. I understand : how ARP works MAC address is an unique address for each NIC IP is network ...
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1answer
125 views

Setting MAC source address to broadcast

How would a network behave if one were to set the source address of an Ethernet frame to the broadcast address FF:FF:FF:FF:FF:FF? Obviously, one would have to manually alter the relevant field in the ...
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2answers
53 views

What Are LAN technologies?

I know about different LAN topologies(like star, bus, ring,...) and that Ethernet is one of the ways to practically implement wired LANs. I wonder what other technologies exist to make LANs? And, is ...
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3answers
148 views

Can Ethernet use fiber optic cables?

I am new to networking, know about Ethernet and that Ethernet cables exist to make a wired networks. I also know about fiber optic cables which have a glass like material inside and transmit light ...
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0answers
25 views

How an MKA key server decides if it shall use MACSec and how it announce that?

According to IEEE 802.1X-2010 the standard for defining MACSec Key agreement protocol Clause 9.6, that's how the key-server decides to use MACSec or no. Each participant advertises whether it is ...
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0answers
142 views

How are required Keys inside MACSec Key agreement protocol (MKA) generated?

I am trying to wrap my head around MACSec Key agreement protocol (MKA) and its relation with MACSec and other protocols. So bear with me. To my understanding in order to MACSec to work, all nodes ...
2
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1answer
87 views

Packet vs Circuit switching

I have a 1Mb/s link each user uses 100Kb/s when active. With 10 user active 10% of the time, I can have 10 users in a circuit switched environment. Packet switching with 35 users, probability > 10 ...
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1answer
192 views

End-to-End delay

I’m working through questions from computer networking top down approach and was hoping to get some clarity on the end-to-end delay calculation. At this stage we are not considering processing, ...
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4answers
715 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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2answers
86 views

Effect of large amount of bare ethernet pairs on network performance

I have a client who has been experiencing a significant amount of performance issues in regards to their telemarketing floor. On my initial assessment, I found that where the ethernet is punched down, ...
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1answer
83 views

Improve ping speed (lower up ping time) [closed]

In normal network with Cisco 3650 (1Gbps) and Linux base servers, the ping time is between 0.150ms to 0.250ms. (I also mean using ping or ICMP is to refer to all protocols) I want to know is there ...
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1answer
602 views

Do we send ack frames in ethernet? if not then how does a router know if its neighbors are down or not?

So first off, do ethernet sends ack frames or not? if it doesn't : then how does a router know whether its neighbors are down or not? if it does : then is it cumulative ack with an ack timer or one ...
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2answers
3k views

Is the MTU of Ethernet still 1500 Bytes?

So basically do the modern routers in the internet still use 1500 as the MTU of Ethernet? or the 1500 Byte was for the old days? What I'm asking here is what is the MTU of Ethernet in modern Networks?...