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

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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 ...
3
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1answer
894 views

Cisco IOS VLAN settings for Dell iDrac with shared interface

We have a few Dell servers with iDrac express, and we would like to start using the iDrac features. Our network is separated into a few VLANs for our different subnets. Our management subnet is on ...
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5answers
9k 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 ...
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3answers
488 views

Get the MAC addresses of all the machines connected to a LAN when NO machines have got an IP address yet

Here is the real scenario. I have say 4 machines not having any IP address yet connected to a switch. In one of the machines (OS=CentOS), I would install a DHCP server and would provide the other ...
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1answer
2k views

What am I misunderstanding about calculating MTU?

Okay, I just finished resolving a jumbo frames issue between a few Xserves, a Netgear GSM7224, and a Drobo B800i. It turned out that the Xserves (Mac OS X 10.6.8 Server) and the Drobo B800i accept the ...
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2answers
408 views

Will all ARP Replies update the ARP Table?

If a computer receives an ARP Reply frame not intended for it, will it update its ARP Table? Example: A, B and C are connected physically and locally. A broadcasts ARP Request to ask for B's MAC then ...
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3answers
810 views

Any program to help me check whether an ethernet channel can support full-length VLAN packet?

Sometimes, I have to face such a situation that I need to quickly and explicitly know whether a full length VLAN packet can traverse between two RJ45 ports. Yes, I mean 802.1Q ethernet frame with ...
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2answers
629 views

“Speed Mismatch” between 1000T and 10000T?

I have a server in a data center, which has an Ethernet NIC card with Fibre support. I have a 1Gbps connection and my ISP asked me to make sure the settings on my device are as follows: Full Duplex, ...
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1answer
920 views

Will RSTP BPDUs be encapsulated in tagged Ethernet frames?

RSTP(Rapid Spanning Tree) is configured on a bridge. All ports of this bridge are "trunk" ports and are part of vlan “x”. Will the BPDUs sent out of this bridge be tagged?
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3answers
4k views

Failed to bring up eth1 in a dual ips solution in ubuntu

I'm using ubuntu 12.04. I tried to assign two ips to two ethernet cards in my server. The content of /etc/network/interfaces is like this: auto lo iface lo inet loopback auto eth0 iface eth0 inet ...
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2answers
587 views

How to create a separated network to customers only?

I work in a company where we have a network ethernet and wi-fi, we would like to create a network where our customers could access our network but don't have access to our computer network. This ...
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2answers
628 views

what is wrong with out of order packets?

when i set up adapter teaming on an HP server, one of the options i'd like to enable is round-robin for transmit load balancing because i need the full teamed throughput to a single host. (this is a ...
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2answers
2k views

What is the difference between flow control and congestion control at layer 2 and 3? [closed]

Is there a difference between flow control and congestion control at the following layers? layer 2(data link layer) layer 3(network layer) If they are not same, then how is each handled at the ...
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4answers
11k views

What happens when ARP Request comes from a different subnet?

What will happen when an ARP Request packet is sent from router1 to router2 in the following two cases? Will an ARP Reply be generated or the ARP Request packet be dropped? ...
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1answer
538 views

What is the effect of stale ARP cache entry on traffic to that DIP till the entry ages out of the ARP table?

If the host, for which an ARP table entry is present on the connected router, has changed its NIC(so that its MAC address has changed), what will happen when a packet is sent out on the link with the ...
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1answer
9k views

Where are ethernet errors logged?

Munin is showing me a graph like this: During that spike, I was unable to access my server through the eth0 port (I could access it through my IPMI port). I'm trying to figure out what happened, ...
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1answer
532 views

stacking two Dell 8024 rack switches

two Dell powerconnect 8024 (8024, 8024F)- rackmount how can these be tied togeather? stacked.. this would be used as interface for dedicated LAN
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2answers
2k views

Increase data transfer speed through bonding/lacp?

I want to maximize the throughput of a data transfer between two servers. The copy will be made at the application layer using Robocopy. To clear things up, please check my Visio schema of the ...
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2answers
541 views

Why WakeOnLAN frames are sent to broadcast

I'm trying to figure out why wake on lan frames, in the simplest form, are designeted to the ethernet broadcast address (FF:FF:FF:FF:FF:FF) and not to the address of the machine to be powered on. ...
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1answer
842 views

Can a limited broadcast packet contain destination MAC address other than FF:FF:FF:FF:FF:FF?

Can a limited broadcast contain destination MAC address other than FF:FF:FF:FF:FF:FF? If the answer is true, could you provide an example of a protocol that uses a packet like this. Ok, to elaborate ...
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5answers
598 views

Share one IP address with a simple router

We have just moved into a new office and have been given our 'internet connection' in the following form: One Ethernet cable in the corner of the room An IP address with subnet mask 255.255.255.0 ...
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2answers
140 views

Ethernet fails just for seconds

I have a clearos gateway linux working as gateway. I have some problems with the conectivity, everything works great but for a few seconds internal ethernet stops working. After 5-10 seconds, it works ...
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1answer
1k 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
610 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
77 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
185 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
468 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
744 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
111 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
403 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
710 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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2answers
1k 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 ...
4
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1answer
206 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
1k 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
3k 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
455 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
127 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
221 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
3k 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
373 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 ...
2
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2answers
641 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
85 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
12k 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
1k 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
1k 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
4k 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
80 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 ...