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

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ESXi5 - 12 Network Interfaces in Windows Guest

I am building a CCIE lab where I will use GNS3 to map virtual router interfaces to physical NIC interfaces which connect to physical switches. I want to build this in an ESXi5 Guest running Win 7. My ...
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212 views

How do I find out which pairs of a CAT5e cable are actually connected to another machine?

Using Linux (Debian, to be specific) on a laptop, I want to be able to check whether, for example, the TX or RX pairs are both connected to another machine. If, say, I've only connected RX (and am ...
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High number of ethernet errors. Tool for testing the ethernet card?

have an Asus Sabertooth X79. I often get corrupted files. I checked the RAM, but memtest finds no errors. To avoid the possibility of disk errors, I tried copying files to tmpfs. If I copy from the ...
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Sanity Check: Is my CAT5e cable probably bad, or do I just need different connectors?

I'm working with a small company, and since I'm the only one with even a half-ounce of network infrastructure experience I've got the job of wiring up our network. So please forgive my newbie-ness. ...
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I have a firewall that supports 1Gbit ethernet ports but 1.4Gbit of traffic, can I make use of a 10Gbit pipe from the router in this case?

We're putting up a rack of servers in a datacenter which provides us either a 1Gbit pipe or 10Gbit pipe from the router (our choice, our package includes 10Gbit). But if we have a firewall which ...
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half-duplex and full-duplex Ethernet vs Switches and Hubs [closed]

From a youtube video I came to know of the following things All machines connected to a HUB are a part of a single collision domain. All machines connected to a SWITCH are a part of a single ...
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386 views

Is it possible to receive dhcpdiscover from ff:ff:ff… mac address?

Today I saw this record in my log files: dhcpd: DHCPDISCOVER from ff:ff:ff:ff:ff:ff via vlan400: network 40.60.100.10/24: no free leases ...
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linux ethernet card ping problems?

I have a very strange problem with my ethernet card. Here is ethernet card details: description: Ethernet interface product: RTL8169 PCI Gigabit Ethernet Controller vendor: Realtek ...
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Bridge to a used eth1 card without losing connection via that card

How can I set bridge between a real eth card on a remote machine without losing my ssh connection to that machine. I ssh into a machine via its eth1 iinterface. 172.168.40.2 255.255.255.0. I ...
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530 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 ...
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475 views

Is is possible to put a tagged vlan on one physical interface on a Force10 S50N switch?

I servers that have a shared ethernet port for IPMI and the first NIC. They have 4-1GbE nics. I would like to bond the nics via LACP while still being able to access the IPMI over a tagged vlan only ...
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190 views

How do I calculate the ethernet NIC-to-NIC time to send a MTU packet (1500 bytes)? (OS-excluded) [closed]

I understand it will depend on the speed of the ethernet 10 Mbit to 100 Gbit. Given an ethernet speed, how do I calculate the time spend in the wire from NIC-to-NIC? I am assuming here that the ...
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How to change 'Advertised pause frame use' and autonegotiation setting on gigabit NIC

I'm investigating some poor nfs performance on a new server, as compared to an old server. Both the old and the new server are nfs clients, and they connect to the same exact NetApp nfs server. My ...
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307 views

How can I 'link' one ethernet Network with a Wireless Network? (Linux) [closed]

I have: WiFi network with SSID=Network1 (running its own DHCP Server and connected to internet). Computer1 with 1 ethernet interface and 1 WiFi interface. Computer2 with ethernet interface. My ...
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107 views

daisy chained layer 2 [closed]

I just read an article about how daisy chaining switches is bad, that one should always do an Ethernet drop directly to the main switch rather than passing by the others, because power issues will ...
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153 views

What do I request from the LAN upgrade contractor to avoid simple oversights? [closed]

The company for which I work have allowed me to hire a LAN wiring contractor to completely overhaul the building LAN. Currently there are old 10MBit Ethernet cables and switches running and I ...
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169 views

Routing traffic externally instead of internal loop

I have one Ubuntu box with 2 network cards. I am running netperf on the computer to measure performance of networking equipment, ethernet coming out of eth0 into the switch then back out into the ...
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bridging two network interfaces in ubuntu linux 12.10 AND being able to access it from that machine

Ok, i have about had it but heres the deal. I have 7 total machines connected like this: [5 workstations]<--->ServerPC<---->MAINPC<---->router FYI, dont worry about the workstations they ...
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586 views

New EFM leased line setup with Watchguard router, vlan tagging issue

I have recently had a 2mb EFM connection installed in a charity I work for. We were not supplied a router because we already had a watchguard XTM330 in storage ready to be used. The line is presented ...
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1answer
54 views

What network traffic when ethernet plugged in [closed]

So in a general sense (e.g. not windows, linux specific) what network traffic is generated when I first boot up/plug in a network cable. Basically: Detect DHCP server Pull an IP Address from DHCP ...
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How do I connect to and access a Cisco router?

I'm a total newbie to Cisco and I have a cisco router on which I have to do some experiments. How can I access this router? Ports available are Ethernet 0/1, Ethernet 0/0, Console, Aux. I guess if I ...
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Enabling jumbo frames on switch but not on devices: looking for trouble?

The switch at hand is a Dell PowerConnect 2716 which does support both VLANs and Jumbo Frames but, as far as I can understand from its manual, it only has a global Jumbo enable/disable setting and no ...
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Changing the default gateway address in Centos

I have a a Centos PC with 2 IP addresses. One of them is because of a back to back connection with another PC, so both run on different subnets. The eth0 has the 192.xx.xx.xxx address and eth2 has ...
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Autonegotiation on laptops for mobile users a must now?

I work in Unified Communications for a company with about 9000 desktops and laptops. I'm part of a team who is implementing and supporting things like Lync and Jabber Video and audio conferencing. ...
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Why is there an EtherType for SNMP?

Today I was reading through some documentation about the fundamentals of networks (IP, Ethernet, MPLS, ...). And while looking at the Ethernet Types that can be used in the Ethernet Frame I saw there ...
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Mismatch between IP address and MAC Address

Suppose you have two interfaces in the host belonging to the same subnet connected to a normal L2/L3 switch port which has a single vlan with interface IP 10.0.0.1. nxge0 (10.0.0.201) ...
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Analyse custom Ethernet frame with WireShark

WireShark can conveniently dissect Ethernet frames, and tell you exactly what each byte means. For example, it tells you where the TCP/IP headers are, how they have been populated and if the checksums ...
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Is it possible to mix jumbo frames VLAN and standard mtu VLAN on the same switch port?

If a managed switch and all attached devices both support VLANs and Jumbo Frames, is it possible to mix VLANs with jumbo frames and VLANs with standard frames on the same switch port / ethernet card? ...
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Why do ethernet cables have 8 wires?

This might seem a stupid question but why do Ethernet cables have 8 wires? Cat5 cables were just using 4 of the 8 wires, so only 4 are actualy 'needed'. Why not 12 or 16 wires?
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Hyper-V Virtual Machine Networking issues related to Max Ethernet Frame Size

I fixed an issue today earlier today but i'm interested in learning WHY it worked. We set up a new Hyper-V virtual machine only to discover that HTTP traffic wasn't working. HTTPS, pings, everything ...
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Packet drops after configuring Ethernet Bonding

I am trying to configure Ethernet bonding for our servers . Both the Ethernet interface in my server are connected to two different network switches physically. Looks like my Ethernet bonding ...
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What are the differences between channel bonding modes in Linux?

Under Linux you can combine multiple network interfaces into a "bonded" network interface to provide failover. But there are several modes, some of which do not require switch support. I'm not ...
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What is the fastest way to connect two machines for a ping-pong test? [closed]

I need to do a latency test between two machines, basically a ping-pong packet test. I wonder what is the fastest connection I can have between those two machines. I imagine my options are: Ethernet ...
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Why is the link between my switch and my router always negotiating half-duplex mode?

I have a Cisco 2950 switch which has one of its ports connected to an Internet router provided by my ISP; I have no access to the router configuration, but I manage the switch. If I leave all switch ...
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What would cause a wired vs wireless speed difference of 16mbps vs 9 mbps? [closed]

Tested via speedtest.net I've set my wireless router to be b/g/n mode (there's no n-only mode on my router). And I am using a USB stick (N, not G) on on PC and an internal wireless on another ...
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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 ...
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ifdown em1 Users cannot control this device. Allow users to control em1 device

I want to allow users to control the em1 device in Linux: When I run this command: ifdown em1 em1 is the embedded ethernet card 1, I want the user to be able to turn off the ethernet card. On ...
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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 ...
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How do I poll the ARP table with an SNMP OID?

When you need to poll the ARP table of a device, conventional wisdom is to use ipNetToMediaPhysAddress or atPhysAddress; however, both of these OIDs are deprecated according to Cisco's documentation. ...
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Is TCP/IP encapsulation MSB or LSB?

Application data sent over TCP experiences multiple encapsulations: The application data is encapsulated within one or many TCP fragments The TCP fragment is encapsulated within one or many IP ...
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How to test/debug bad network wiring?

I recently bought a place already wired with Cat 5E (8 ports, leading to a central closet). However attempting to get link, nothing works. On closer examination, it was obvious that the ends in the ...
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What is the clock frequency inside 10Gb and 100Gb Ethernet cards?

As I understand, a 10Gb Ethernet card is capable of putting 10Gb every second on (say) a fibre optics cable. Now naively, for this to happen in hardware, one will need a 10GHz clock running the ...
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128 views

Two network cards latency

I'm trying to setup a network architecture where one network is a low-latency low-bandwidth tcp control system (GBit), the other is a high-bandwidth udp (maybe tcp) network that could get saturated ...
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492 views

arp across subnets which devices can be detected?

i have some devices connected in the same physical network (LAN) but in different subnets. I want to detect them all with the ARP from my computer. My Computer is also in the same physical network but ...
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Can't start eth1 and dhcp on debian wheezy

What I want: eth0 is connected to internet and has a static IP-address. eth1 connected to internal network and be a dhcp server for subnet. But I can't get eth1 to work. Error: $ ifup eth1 ...
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Client not getting address from some DHCP server

I'm working on some embedded devices which should be connected to a large network (hundreds of devices) via ethernet and that should be configured using the DHCP protocol. What I'm experiencing is ...
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Difference between ethernet switch and ethernet pass-through

Most blade server systems can have an ethernet switch module or an ethernet pass-through module. What is the difference between both? Is the pass-though module simply "dumb" as a hub? Why would you ...
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Why is there no autonegotiation for ethernet jumbo frames? [closed]

Having read up a bit about ethernet jumbo frames, I'm wondering. There seem to be technical advantages to being able to use larger than 1500 byte ethernet frames in some cases. Just enabling jumbo ...
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How to test cat5/cat6 cable runs, using software-only, or simple tools?

Are there any utilities or simple tools or techniques to easily test a CAT5 cable, to see how well was it installed? Cat5 is often installed by amateurs, but has been installed and "working" for ...
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LAN: What are the things to look at when arriving in a new place

My company is moving to a new place, and the only thing I know about the cabling is that there are cables and a patch panel. I have no idea about the cable speed, quality, and I'm a software guy with ...