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

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1answer
205 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
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2answers
2k 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 ...
0
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1answer
234 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
248 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 ...
2
votes
2answers
242 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 ...
1
vote
1answer
186 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
votes
3answers
877 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
48 views

Calculation units in EtherType frame field [closed]

The EterType ethernet frame field value is represent a payload field length in bits or bytes?
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0answers
23 views

Interface eth0 not reacheble outside LAN

First of all, sorry for my bad english. I configured my two interfaces, eth0 and eth1! Bove have the LAN IP 192.168.0.10 and 192.168.0.11.... everything ok. The problem is, eth0 is reacheble from ...
3
votes
2answers
349 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 ...
0
votes
1answer
104 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 ...
0
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1answer
65 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 ...
0
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1answer
100 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
votes
1answer
341 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 ...
0
votes
1answer
499 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. ...
1
vote
1answer
39 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
votes
1answer
382 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 ...
3
votes
2answers
307 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
votes
1answer
190 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 ...
0
votes
1answer
50 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
1k 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
votes
1answer
184 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
228 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
2k 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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0answers
91 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
889 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
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1answer
243 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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0answers
210 views

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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4answers
1k 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
346 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
384 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 ...
0
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1answer
163 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 ...
2
votes
2answers
3k 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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votes
1answer
251 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
91 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
137 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
votes
1answer
120 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
1k 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 ...
1
vote
2answers
475 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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votes
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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votes
3answers
1k 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
1k 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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votes
1answer
543 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
78 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. ...
3
votes
2answers
265 views

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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2answers
822 views

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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2answers
254 views

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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0answers
1k views

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? ...
34
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6answers
21k views

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?
3
votes
1answer
412 views

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 ...