Ethernet is the most common set of standards for wired connections in local area networks.

learn more… | top users | synonyms

45
votes
2answers
27k views

How do VLANs work?

What are VLANs? What problems do they solve? I'm helping a friend learn basic networking, as he's just become the sole sysadmin at a small company. I've been pointing him at various questions/answers ...
0
votes
3answers
558 views

What is the difference between a hub and a switch?

I'm sneeking around online store for used stock of hubs, routers and switches for a project I have to build a network infrastructure. So far, I have bought: 1x Cisco 2514 Router; 5x Cisco Serial ...
2
votes
2answers
3k views

Fedora 17 ifconfig eth0 returns an error message, why did linux change eth0 to em1?

I have a fresh install of Fedora 17 installed, 64 bit. Everything works flawlessly, It connects to the internet automatically when I plug in the internet cable. So I'm kind of confused when I ...
70
votes
17answers
26k views

Should network hardware be set to “autonegotiate” speeds or fixed speeds?

We recently had a little problem with networking where multiple servers would intermittently lose network connectivity in a fairly painful-to-resolve way (required hard reboot). This has been going on ...
3
votes
2answers
2k views

How do I dynamically obtain IP addresses for VLAN interfaces?

I have an Ubuntu machine on which I have created four VLANs, namely eth0.100 ,eth0.200 , eth0.300 and eth0.400. I want to dynamically obtain the IP addresses using the DHCP server. It should provide ...
0
votes
3answers
372 views

Bonding: works only for download

I would like to install bonding with 4 links with mode 4. but only "download/receiving" works with bondig. for transmitting the system chooses one link. ifconfig bond0 Link encap:Ethernet ...
0
votes
2answers
102 views

Raw 802.3 through ethernet switch

At work I have a bunch of devices that communicate to and from a computer using raw 802.3 ethernet. Communication to the devices is mediated by a little program a coworker wrote, which uses the ...
17
votes
2answers
6k views

What is the “in-the-wire” size of a ethernet frame? 1518 or 1542?

According to the table here, it says that MTU = 1500 bytes and that the payload part is 1500 - 42 bytes or 1458 bytes (<- this is actually wrong!). Now on top of that you have to add IPv4 and UDP ...
7
votes
7answers
14k views

Is it possible to match an internal IP address to a switch port?

I'm trying to find a computer that has a certain IP address on our internal network. I have identified the computer name from DNS, but in this case it does not help me. Just wondering if I can ...
4
votes
3answers
7k views

Ethernet frames: what are the source and destination MAC addresses?

Imagine you have some network configured like this +-----+ +------+ +------+ +-----+ |comp.|---|bridge|---|router|---|comp.| | A |---| B |---| C |---| D | +-----+ +------+ ^ ...
9
votes
1answer
2k views

Ethernet interface errors

My Ubuntu servers ethernet interface that connectes to ISP's multiplexer shows errors. Here is the snapshot: RX packets:204564288 errors:3193970 dropped:0 overruns:0 frame:3138402 ...
7
votes
5answers
7k views

What is the disadvantage to cascading multiple switches?

I have to wire a new office for ethernet and the contractors want to charge atrocious amounts for each line running to each room in the office. It will be much cheaper for me to run a single line to ...
5
votes
3answers
1k views

Multiplexed 1 Gbps Ethernet?

Is it possible to multiplex two (or more) 1Gbps Ethernet into a single logical connection? Is it common place? Advisable? Stupid? Other considerations? I ask because my hosting partner's network ...
10
votes
7answers
909 views

10 gigabit networks: Decieding between fiber and twisted pair

With a green field installation 10gbps network (no legacy equipment to support), why would one select one physical medium over the other? If left to impulse, I'd probably go with fiber optics over ...
4
votes
5answers
6k views

Does a single LACP channel over multiple switches increase redundancy?

I am curious for opinions, findings, or evidence that having multiple interfaces bonded using LACP to ports in multiple switches can increase redundancy. Previously bonded interfaces have always been ...
2
votes
1answer
813 views

Physical network setup for pfsense w/ CARP for redundant firewalls

So I'm looking at this diagram: http://doc.pfsense.org/index.php/Configuring_pfSense_Hardware_Redundancy_(CARP) Does this assume that the "DSL Router" at the top of the drawing has two physical RJ45 ...
2
votes
3answers
414 views

Ethernet: network topology

Consider a standard GigE network switch. In order to do the switching, presumably it needs to maintain a map of MAC addresses of all things that exist on the network to its (switch's) port numbers. ...
2
votes
5answers
2k views

Link aggregation with DSL and Ethernet, and different ISP's?

We're a webdev company that has outgrown its ADSL bandwidth. It's currently 4/1 Mbit/s and due to distance we can't simply get faster DSL, whether ADSL or SDSL. Stacking multiple DSL connections is ...
2
votes
7answers
310 views

How to separate the display and peripherals from the actual computer?

I am trying to see if its possible to toss all the computers in the server room and just run cables out of it. The end goal is you just sit down at your desk and all you have is a display and ...
1
vote
6answers
5k views

physical port locks for ethernet, USB, phone, etc.?

If a user or a visitor sees a port, they will try to stick something into it and then complain to us when it doesn't work or breaks their stuff. Are there such things as physical locks that can be ...
3
votes
1answer
171 views

Missing Ethernet preamble [closed]

I am helping my colleague debug his problem. Basically, there are two 10M devices, and only one of which we have control over (the other being a "black box"). Analyzing the Ethernet hardware signals ...
2
votes
4answers
6k views

Ethernet Loopback plug - running a ping

For a project at work, I need to be able to test various Ethernet NICs by connecting them to a "loopback adapter plug", like this one on various embedded Linux boxen that come off a production ...
1
vote
2answers
257 views

ethernet cable is connected but It shows unplugged [closed]

I told datacenter too connect two of my servers with a crossover cable to each other. But when I try this command ethtool eth0 Settings for eth0: Supported ports: [ TP ] Supported ...
1
vote
1answer
403 views

Good reference for Cisco Resilient Ethernet Protocol [closed]

I have been trying to understand Cisco's Resilient Ethernet Protocol, but am unable to find a proper source to read from. I checked the Cisco site and also their White Paper on REP. But none of ...
0
votes
4answers
624 views

Ubuntu is showing weird HWAddress for eth0 after a power failure

Recently, my ubuntu box encountered a power failure. After rebooting, the HWAddress of eth0 is showing a very weird number: 00:00:00:00:00:30. I have tried sudo ifconfig eth0 down & sudo ifconfig ...