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

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CentOS Network Interface Priorization

I have a CentOS server with 2 network interfaces with configurations: eth0: DEVICE=eth0 BOOTPROTO=none BROADCAST=10.0.0.255 HWADDR=xx: IPADDR=10.0.0.2 NETMASK=255.255.255.0 NETWORK=10.0.0.0 ...
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1answer
590 views

Is it possible to use WPA2 over ethernet?

Like, as in requesting a "password" to connect, just wondering. Also, are any of these (VPN, public key auth?) methods either possible or implemented?
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1answer
3k views

OpenVPN to host tap device having very large MTU

Question What is the minimum set of server and client configuration directives that I need in order to satisfy the following conditions? Virtual layer 2 ethernet network that will not be bridged ...
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3answers
6k views

Can Wireshark capture an entire Ethernet frame including preamble, CRC and Interframe spacing?

I am examining an Ethernet frame in Wireshark. According to the "Ethernet frame" Wikipedia article and accompanying diagrams, "A frame starts with a 7-octet preamble and 1-octet start frame delimiter ...
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1answer
2k views

10GbE be2net low pktgen performance

I am testing the network performance of two workstations, each having 2.4GHz Xeon quad core processors and NC550SFP PCIe Dual Port 10GbE Server Adapters, linked back to back. I've checked the ...
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1answer
540 views

Source and Destination Packets on Wireshark Relative or Absolute?

New in Packet Analysis. Sniffing on the Ethernet device of my computer. Does the Source and Destination columns on Wireshark tell the source and destination from where the packet was originated and ...
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2answers
192 views

Switch between network configurations via command line in fedora 17

I have two different setups I use on my work laptop; one enables synergy over an ethernet ssh tunnel with my work computer on the local network, and the other opens an HTTP tunnel to my work computer ...
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2answers
547 views

Tunnel Ethernet Packets over SSH

I have two machines. My laptop and a machine in the local intranet. This machine has next to the network device (for the intranet) a second network card. I want to send raw ethernet frames out of this ...
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1answer
345 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 ...
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2answers
7k views

Is the 64-byte minimal Ethernet packet rule respected in practice?

A quick WireShark scan of my network interface reveals a bunch of Ethernet packets which are less than 64 bytes in length. I know that WireShark strips off the trailing 4 byte CRC, but I still see ...
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1answer
456 views

Enabling Ethernet X3530 M4

I have IBM X3530 M4, and it appears to have 4 ethernet ports, but under Ubuntu just 2 ethernet ports are enabled. How can I enable the other two ethernet ports?
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2answers
347 views

Extending a PaGP EtherChannel run beyond the maximum ethernet length [closed]

I have an office downstairs which requires approximately 500 feet of cat-5 to reach. We have a basic L2 switch in a closet at the halfway point which acts as a signal booster, and allows us to give ...
3
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2answers
793 views

How do fiber Ethernet transmitters set their power output?

I've noticed that fiber-optic SFP modules from Cisco and the like often specify a range of power outputs, such as -3 to -9 dBm. What determines the actual power output we should expect to see from ...
2
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1answer
246 views

Bond0 Failover when link light stays up: High Availability Network

Configuration: Two switches, each with a separate internet route Centos servers with eth0 and eth1 bonded as an active-backup on bond0, eth0 in on switch and eth1 in the other /etc/modprobe.conf ...
4
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3answers
2k views

Effect of reversing a pair, in cat5 cabling (e.g. swapping stripe and solid)

Is there any practical effect of reversing solid and stripe, when wiring cat5 cables? But if I've got a cable where each pair is a pair but one end is flipped, will this make any practical difference ...
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1answer
63 views

Calculation units in EtherType frame field [closed]

The EterType ethernet frame field value is represent a payload field length in bits or bytes?
3
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2answers
671 views

Need to “extend” wireless signal to conference room

We have a network set up using an ASUS RT-N66U for our office with the following configuration: Private SSID (one for 2.4 GHz and 5 GHz) Guest SSID (one for 2.4 GHz and 5 GHz) Unfortunately, we've ...
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1answer
143 views

obtain the MAC Address/interface name from GUI on FreeBSD?

Is there any way I can obtain the MAC Address/interface name from GUI on FreeBSD? Are there any system calls to do that? I was searching everywhere but couldn't find any information. Can you please ...
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1answer
71 views

How to build a L2 Ethernet with 1000 comupters?

We don't really have 1000 computers. I'm asking this question just because my brain is blocked here. If I put a number of, say 1000, computer on a L2 Ethernet. Since most of L2 switch has only maybe ...
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1answer
111 views

Multiple ethernet interface on one ethernet card

First I must say that I am new in linux and maybe I will ask trivial question. My job is to create 8 ethernet interface to be visible in kernel, but all of them should send and receive data through ...
6
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1answer
751 views

Why do metal fasteners (e.g., staples) around ethernet cables impair network performance? [closed]

At one point I was living in a 6 bedroom home that had cat 6 ethernet wired to each bedroom. The internet connection to the bedrooms furthest from the cable modem had terrible performance, though I ...
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1answer
1k views

troubleshoot Ethernet (layer 2) without layer 3

I am troubleshooting a LAN and the problem is to make sure each host can reach each other at layer 3. Each host is configured to the same subnet, but some hosts cannot reach other at layer 3 (e.g. ...
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1answer
41 views

Use or not to use multiple ips on the same network card?

I got a Dell r620 that cames with 4 network interfaces. If I have for example 4 ips, and want to assigne them to the server. What would be better, in terms of performance. Add all the 4 ips to the ...
4
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1answer
915 views

command for MAC broadcast

I am looking for a command to discover all hosts on the same LAN segment from a host with unassigned IP, default gateway, and subnet. I know there's ping 255.255.255.255 but that operates at layer 3 ...
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2answers
361 views

How can I make a secondary NIC port “eth0”?

I am using CentOS 5.9. One of my servers recently had a malfunctioning NIC port. The software running on the server was hard-coded to use eth0. The other physical NIC ports were fine and unused. The ...
4
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1answer
278 views

Supress FreeBSD “link down: cable prοblem?” messages

I have a FreeBSD lab machine that is regularly connected and disconnected from the network, sometimes to borrow the port temporarily for another machine and other times to test the ability of certain ...
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1answer
55 views

How to determine remote link speed?

I'm on a non-manageable switched 1 GbE network with mixed 100 MbE and 1 GbE hosts. Is it possible to tell if a certain host has a certain link speed without looking at the status LEDs of the switch ...
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1answer
2k views

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 ...
2
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1answer
232 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 ...
2
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2answers
299 views

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 ...
4
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3answers
4k views

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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1answer
130 views

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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2answers
2k views

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 ...
5
votes
1answer
484 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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4answers
2k views

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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2answers
674 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 ...
4
votes
1answer
594 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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1answer
212 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 ...
3
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2answers
6k views

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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1answer
396 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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votes
1answer
116 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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2answers
174 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 ...
0
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1answer
211 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 ...
1
vote
1answer
2k views

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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2answers
657 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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3answers
5k views

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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3answers
2k views

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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1answer
743 views

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 ...
3
votes
2answers
83 views

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. ...