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

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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
9k 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
476 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
7k 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
499 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 ...
9
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2answers
512 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
783 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
573 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
138 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
573 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
75 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 ...
3
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3answers
184 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
423 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
681 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
370 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 ...
4
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1answer
640 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
194 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
949 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
431 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
125 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
213 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
325 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
621 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
83 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
10k 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 | +-----+ +------+ ^ ...
4
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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
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
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 ...
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5answers
3k 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
78 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 ...
0
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1answer
130 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
1k 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
362 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
444 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
4k 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
312 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 ...
9
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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
53 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 ...