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

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How to pervent vtp updates coming from vmware to go towards switch?

To get the background of this question please follow this link http://security.stackexchange.com/questions/14803/using-nessus-an-alien-packet-from-switch-shut-down-my-ethernet-card-completely I have ...
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1answer
905 views

Linux server equivalent of Cisco Discovery Protocol (CDP)?

I am wondering if there are any Linux tools out there which might aid in identification of hosts directly connected to each other (much like Cisco Discovery Protocol on switches)? I have found ...
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1answer
504 views

bonding driver in centos 5.5,mode balance-rr not work

i've creat a bonding interface in centos 5.5,i chose mode balance-rr,using slave eth6 and eth7,and the link of eth6 and eth7 is ok,here is the configuration file: [root@50:B3:42:00:00:A3 ...
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1answer
74 views

What type of connection to get for a web server [closed]

I've been doing some research about this topic but I had no luck finding my answer. Will a 2Mbps G.SHDSL connection do the work or should I go with a 5/10/20Mbps Metro Ethernet connection? Or am I in ...
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3answers
180 views

What could cause two devices to refuse to link?

This is a curious case where all the devices at hand will link with one another, except for two that just won't detect one another. One device is a single board computer (SBC) with a gigabit nic, the ...
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1answer
352 views

How do you explain ethernet cable problems to non networking people? [closed]

We've recently been doing a large network migration in our datacenter. We've had a few cables in this start to deliver really bad pings (in excess of 500ms on a LAN) before they could be replaced. ...
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2answers
623 views

Ubuntu Server forgets how to connect using ethernet

I have encountered a series of errors after my Ubuntu server was restarted. It seems to have forgotten how to connect to my router as it cannot ping local or other IPs. When I start it up it says ...
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1answer
1k views

Very low throughput on 10GbE network

I have two Linux machines, each equipped with a Solarflare SFN5122F 10GbE NIC. The two NICs are connected together with an SFP+ Direct Attach cable. I am using netperf to measure TCP throughput ...
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1answer
105 views

Tools to inspect an ethernet packet travels through host's interfaces?

I am debugging a local ethernet connection on a Linux machine. I want to inspect the ethernet packets as they travel. in and out current machines' interfaces. I do not have a GUI on the machine. Is ...
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3answers
320 views

Is it possible to cross-connect two AUI ports without transceivers?

Many Ethernet devices predating the ubiquity of RJ45 transceivers had DB15 "AUI" ports. One is ordinarily expected to attach a transceiver for either coaxial or twisted-pair Ethernet. Is it possible ...
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1answer
516 views

Understanding Ethernet Headers, What MTU Do I Need?

I see many articles on line stating that the overhead of Ethernet is 18 bytes (example: http://www.learnios.com/viewtopic.php?f=8&t=18887) Looking at this wiki article ...
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937 views

Internet slowed down because of SQUID Server setup

Recently I have setup a squid server for our office. I have computer (A) with two ethernet cards, one for internet and the second one for local networkIt has Ubuntu server OS with squid-server and ...
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1answer
175 views

Does using VLANs in your network infrastructure cause an appreciable decrease in performance?

This is something I've never considered before and wanted the opinions of the experts. We use VLANs day in and day out for various network tasks. My modus operandi is that in general, if something ...
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2answers
1k views

Linux bonded Interfaces hanging periodically

I've several hosts that are showing problems with connectivity. When working from the command line, for example, typing is frozen for a second or so, then recovers - then it does it again. The most ...
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4answers
763 views

Trunk fiber ports on switches

We are planning to purchase new switches for our network. We have three buildings in the same area that are all connected by fiber. Our main building is very large and needs to be connected by fiber ...
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1answer
2k views

Ubuntu Linux - two interfaces, same subnet, different vlan - MAC/ARP issues

I'm attempting to setup a server that needs to have interfaces on the same IP subnet, but different VLANs: eth1.102 Link encap:Ethernet HWaddr 00:50:56:b1:00:0f inet addr:10.1.1.6 ...
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3answers
404 views

Cut network cables in Cisco 2960 PoE

We've a Cisco 2960e that services our VoIP phones and other things. I inherited it. The question I have is the cut cables: there are about four network connectors that are cut about 1cm away from the ...
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1answer
121 views

Linux network adapter keeps changing settings

I'm running CentOS 5 and noticed for the past week that eth0 settings keep changing and I have to reset them. Any ideas what it might be or where I need to start?
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1answer
188 views

Can a host launch a DOS attack on Ethernet?

Here is my trail of thought: Since Ethernet works on the principle of CSMA/CD one can possible setup a rogue host which transmits packets all the time forcing other to exponentially back off until ...
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2answers
2k views

Serial to ethernet cable: how to connect to device

How can I use a serial to ethernet cable to connect to a device: in my case a Hp ProCurve AP? A serial to USB or serial to serial would have been great but I found this serial to ethernet cable from ...
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2answers
281 views

Is it possible to wake a computer connected directly to its NIC?

If two computers are connected by ethernet directly (ie, with no router between them) can one computer wake the other using the magic packet? I ask because it's not working for me and I'm not getting ...
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1answer
2k views

How to troubleshoot the suspected ethernet card failure [closed]

Sometimes one of the laptop when attached to the dock would drop the ethernet connection. By constantly pinging the default gateway usually there are no packet drops but sometimes, it results in ...
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2answers
594 views

Ethernet over IP

I need to merge two L2 broadcast domain into single domain and I have to do this over unmanaged by me L3 IP network. All that I could find is vtun utility for linux. Which software&howto you can ...
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2answers
80 views

2 networks with a layer 2 bridge that shouldn't be there.

I have 2 separate networks that I manage. They have a router between and layer 3 connection is working fine. Last week my DHCP servers started handing out IPs across the networks, looking around I ...
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3answers
8k 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 | +-----+ +------+ ^ ...
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3answers
960 views

Phantom NIC issue causing eth0/1 to drop out

We are experiencing a very strange and frustrating problem. Our company has servers here in Massachusetts, as well as in California. The issues we are seeing are only on the CA hardware. Out in CA, we ...
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1answer
832 views

Why is half-duplex mode supported for 10BASE-T and 100BASE-TX networks?

I'm currently learning about Ethernet standards, auto negotiation and duplex mismatch. That made me wondering why half-duplex operations is allowed in 10BASE-T and 100BASE-TX networks. Wouldn't it ...
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1answer
3k views

Solaris ethernet ports: e1000g1 and e1000g2 are not working

I can plumb and configure e1000g0 and e1000g3 using ifconfig, but I can't seem to make use of e1000g1 or e1000g2. When I try ifconfig e1000g1 plumb, I get ifconfig: plumb: e1000g1: Invalid argument. ...
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1answer
79 views

My business computer doesnt connect to any ethernet device outside business lan [closed]

My computer which i use at work is within a domain. And our internet connection is through some kind of filter. So in Internet Explorer, there is a configured lan setting. When i try to connect any ...
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5answers
2k views

Virtual interfaces with default routes

My Ubuntu Server has one physical interface eth0. I want to assign 3 ip's (different subnets) to the server. I cannot use the default virtual interface creation tools like ifconfig or ip addr add ...
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1answer
69 views

Accessing a connected device through LAN [closed]

I have a metered APC Power Distribution Unit (PDU) which is capable of spewing out the current load, power and such information through a LAN cable. I'm connecting the cable from the PDU to a server ...
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1answer
121 views

Netgear FVX538v2 slow whene connected to Canoga Perkins N525 ETSU

First of all thank you in advance for helping me. my issue is the old network admin found a problem whene he connected the firewall and the ETSU together the through put went down to less than 1 mega ...
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1answer
912 views

QLogic QLE8152 won't link up with a fiber loop

I have a Dell R710 running Debian Linux 6.0 (Squeeze). I installed a QLogic QLE8152 CNA in the PCI-E riser today and I have been trying to get the CNA's ethernet layer to come up after I put a fiber ...
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1answer
2k views

Would the source and destination address in ethernet frame change?

Say there are 2 computers are connected this way in a wireless network: Computer A -> Access Point 1 -> Access Point 2 -> Computer B When a frame is sent from Computer A to Computer B, the frame ...
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1answer
349 views

How to determine the interface name for 2 Ethernet adapters with 8 ports?

I have 2 Ethernet adapters on a 2U server, each of them has 4 ports, for a total of 8 ports. Is there a way to find out the interface name(eth0, eth1 ...eth7) for each port without connecting to a ...
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5answers
396 views

Is a Router required to set up a network? [closed]

Is a router required to set up a network? Suppose I have just an Ethernet wire and then I fix it up to 3 computers. Can I then say that these computers are now in a network? If they are in a ...
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6answers
3k views

Direct ethernet link between two servers

Say I had two servers which needed super-low latency (Database, file etc.). Would it be possible to directly connect the two servers with 10GbE, so each server had 1 (in the real world it would have ...
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2answers
295 views

Two network adapters with the same ip

I have two network adapters that use the same ip range, but are different networks. I tried this but it didn't work: iptables -t nat -A OUTPUT -p all -d 1.2.3.0/8 -j DNAT --to-destination ...
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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 ...
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1answer
52 views

Two network Macs have slow internet

I work in a boutique advertising agency as a web developer. I have my own servers at home for my website. In our office, we have 8 Macs. Two of the iMacs are against one wall with an ethernet cable ...
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3answers
1k views

What is, and what problems result in a 'carrier error'

I haven't found a really clear definition about what a 'carrier error' is within the context of the ifconfig output for a interface. I have been searching on Google and there really isn't a great ...
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3answers
276 views

Ethernet link negotiates a connection only in half duplex mode

I have a NIC which is capable of 100BaseT/Full. But it negotiates a connection only on 100baseT/Half mode. Here is the output of mii-tool: eth0: no autonegotiation, 100baseTx-HD, link ok The ...
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2answers
972 views

Ubuntu Server, 2 Ethernet Devices, Same Gateway - Want to force internet traffic through 1 device (or at least allow it to work!)

I have a Ubuntu 10.04 Server with 2 ethernet devices, eth0 and eth1. eth0 has a static IP of 192.168.1.210 eth1 has a static IP if 192.168.1.211 The DHCP server (which also serves as the internet ...
0
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1answer
102 views

Server can only make outbound connections

My server is running Ubuntu 10.04 and is connected by ethernet to a router/modem device. The problem is that it's basically ignoring incoming connections. So I can't SSH into it or access the ...
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0answers
838 views

Descriptions of Ethernet register/counter names?

Is there a manual/datasheet/some other resource that explains what do all these counters in ethtool -S <interface> mean? Some of them are self-explainatory, some aren't... I'm taking them from ...
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197 views

Intel Server Board: Ethernet MT connection vs PM connection

What's the difference between an MT ethernet connection and a PM ethernet connection? Intel server board has two ethernet ports that are named in that manner.
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2answers
399 views

Carrier ethernet vs Metro ethernet or any other alternative?

We have three remote offices (office A, B, and C), two (Office B and C) of them need to access the Linux file server and web application server in Office C. We also need to administer the network of ...
3
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1answer
335 views

Programatically extracting interface configuration from the system?

I would like to produce a list of all the interfaces available on a [Linux] system, and for each interface, produce a list of available IP addresses. I was hoping to do this in a more graceful ...
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1answer
367 views

Multi-NIC Linux machine's NICs are responding to each other's ARPs regardless of arp_filter setting

I have an old Linux machine running a 2.4.37 kernel. In the machine are two NIC cards both on the same network with different IPs. For some testing, we want each IP's traffic routed through that NIC, ...
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4answers
141 views

Linux - Is there a way to determine what mac addresses an interface has seen traffic from?

Yes, I know about ARP but that relies somewhat on IP layer connectivity in that the remote system must be configured with an IP on a recognized subnet. Is there any way to just dump off what mac ...