A Network Interface Card is a computer component which connects to a physical network in order to send and receive data.

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26
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7answers
9k views

How fast is 127.0.0.1?

I wonder it it is tied to my NIC at all or if the OS or driver intercepts and immediately returns data sent to the loopback address? Do the electrons actually travel to my NIC then the NIC returns ...
24
votes
2answers
15k views

What is the command to flash a NIC link light?

I remember using a command line tool to flash a NIC's link light to identify it. I can't remember for the life of me what it was.
22
votes
11answers
37k views

Windows Server 2008: specifying the default IP address when NIC has multiple addresses

I have a Windows Server which has ~10 IP addresses statically bound. The problem is I don't know how to specify the default IP address. Sometimes when I assign a new address to the NIC, the default ...
18
votes
5answers
8k views

What network loads require NIC polling vs interrupts?

Does anyone have some data or basic calculations that can answer when frame coalescing (NAPI) is required and when a single interrupt per frame is sufficient? My hardware: IBM BladeServer HS22, ...
17
votes
7answers
23k views

Can a single network card have 2 IP addresses?

Are network cards and IP addresses a one-one map?
17
votes
2answers
1k views

What is the fall off of subsecond throughput on Ethernet Network Interfaces

On a network interface, speeds are given in term of data over time, in particular, they are bits per second. However, in the uber-fast world of computing -- a second is kind of a really long time. So ...
11
votes
10answers
14k views

Is there any reason to have 2 NICs on a server?

Is there any reason to have 2 NICs on a server BESIDES the following cases? You need to connect to 2 different physical networks Redudancy (1 NIC fails, so you use the other) Are there any other ...
11
votes
2answers
2k views

Multiple IP addresses per NIC

How can I have multiple IP addresses assigned to a single NIC? I remember doing this on Unix way back when. Can it be done on Windows?
11
votes
3answers
12k views

e1000e Reset adapter unexpectedly / Detected Hardware Unit Hang

I have a Dell 1U Server with Intel(R) Xeon(R) CPU L5420 @ 2.50GHz, 8 cores running Ubuntu Server Kernel Version 3.13.0-32-generic on x86_64. It has dual 1000baseT networking cards. I have it set up to ...
10
votes
3answers
11k views

PCIe x8 NIC in PCIe x16 slot

I have a motherboard with only one x16 PCIe slot and no x8 slots. I am buying a NIC with very specific configuration, but it is available for x8 slots only. Can I plug a x8 card in a x16 slot? I have ...
10
votes
1answer
11k views

NAPI vs Adaptive Interrupts

Could anyone please explain how two following technologies are used to mitigate interrupt overhead under high networking load? Adaptive-rx/Adaptive-tx, and NAPI; I would appreciate an answer that ...
9
votes
2answers
938 views

MAC addresses on dual-NIC mainboards

Here's a weird problem. We've got a number of devices with dual-NIC mainboards. Some are Realtek NICs, which suck. Some are Intel e1000s, which don't. I've just noticed on 2 machines, one is an ...
9
votes
2answers
14k views

Many dropped packets of my NIC

I have a server running on CentOS 5.3 (a comet chat server, will have lots of tcp connections). Recently I found it was very slow (http service and ssh) so I use "ifconfig" command to figured out what ...
8
votes
5answers
13k views

Is it possible to connect a single NIC to two different VLANs?

I know it is possible to assign multiple IP addresses to the same NIC as long as they are on the same sub-net (e.g. server A can be assigned both 192.168.1.1 and 192.168.1.2). However, is it possible ...
8
votes
1answer
21k views

How GRO (generic receive offload) works on more advanced NICs?

I am interested in particular answers: Does the NIC with GRO edits/creates TCP ACK or any other packets (or is this feature transparent to receiver/sender TCP stacks)? There should be a timeout/...
7
votes
2answers
571 views

Can I have 2Gbit over 1Gbit Nics [closed]

So this really baffles me. Apparently because 1Gbit can transmit data in both directions simultaneously it should be possible to get 2Gbit of data transfer on a single NIC (1Gbit flow seend and 1Gbit ...
7
votes
1answer
2k views

How can I confirm if my vmxnet driver is installed on my CentOS server?

I have an appliance running CentOS 5.x on VMWare ESX. Quite recently I upgraded it to a newer version of CentOS (still in 5.x) and I noticed that the network card wouldn't initialize. If I run ...
7
votes
2answers
5k views

NIC Teaming with Broadcom on HyperV 2008 R2

I have a HyperV cluster made up of 3 hosts. Each host is connected to both of my Nexus 5548 switches running in an etherchannel. LACP on the switch and NIC teaming using Broadcom 802.3ad on the server ...
6
votes
4answers
28k views

PCI Express x4 network card into PCI-Express x16 slot?

Is it possible to plug in PCIe x4 NIC into PCIe x16 slot?
6
votes
3answers
1k views

So what really makes a server grade NIC?

We have a couple servers hosting Citrix VM's. We are planning on adding SAN storage to our network so that we can do the quick migration and high availability thing. The question comes up with ...
6
votes
3answers
9k views

Is APC's smart-signaling cable (940-0024) really proprietary?

First, not sure if this question belongs here or SU, so please advice accordingly before wildly down-voting or blasting me. We have a UPS unit for which we recently configured to work on our network. ...
6
votes
5answers
283 views

Is it “OK” to use a low end NIC for a dedicated heart beat between two servers?

I've got nice big server-grade NICs on my servers busy interfaces. Soon I'll be setting up a cluster that will have a dedicated heat-beat. Do I really need to use an expensive server grade NIC for ...
6
votes
1answer
8k views

Assign individual NIC to KVM guest

I have a server with 6 NICs installed and is running Ubuntu 12.04LTS. I want to setup 4 guest VMs using kvm. Now I want to assign 2 NICs for the host(1 Public IP and 1 private IP), and 1 NIC each to 4 ...
5
votes
4answers
11k views

multiple physical interfaces with IPs on the same subnet

I have a linux box with 9 NICs on it, and I want eight of them to have unique addresses on the same subnet, e.g.: ifconfig eth1 192.168.123.1 netmask 255.255.0.0 ifconfig eth2 192.168.123.2 netmask ...
5
votes
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 ...
5
votes
1answer
1k views

How can I stop Azure from randomly replacing network cards on VMs?

Azure seems to have the habit of randomly changing the hardware configuration of virtual machines, without telling anything to the user. This is of course mentioned in the documentation, although ...
5
votes
3answers
7k views

How to improve Intel X520-DA2 10Gb NIC throughput without Jumbo packets

Here's what I have done so far: Using more Rx/Tx buffers boosts performance the most from defaults. I set RSS Queues to 4 on each adapter, and specified starting RSS CPU on the second port to ...
5
votes
3answers
463 views

Bonding with 2 NIC's and 2 reserves?

I have a server with 4 ports (2 adapters with two ports each). I want to connect two ports to the local switch and two other ports to the external switch. This local switch has an uplink to the ...
5
votes
2answers
10k views

CentOS not detecting Intel 10G (ixgbe) interface

I have a server with CentOS 6.5 installed with 2x 1Gbps Ethernet Cards, I have added a new interface (Intel(R) 10 Gigabit PCI Express Network) but the problem. is the system is not detecting the ...
5
votes
1answer
7k views

eth0 NIC Link is Down repeating message in kernel log

I've noticed since few days ago that same repeating kind of messages occurs and I positively can say that nothing was intentionally changed (installed/uninstalled) in that period. here's sample of /...
5
votes
1answer
2k views

Intel NIC X540-T1 non-functional in Ubuntu Server 12.04

I have installed three Intel X540-T1's in servers running Ubuntu Server 12.04, but all are non-functional, no link lights, no packets sent or received, and no connection on ip4 or ip6 whether set up ...
5
votes
3answers
2k views

Broadcom BCM5716 Hangs on CentOS 6 Boot

I have a fresh CentOS 6 installation on a Dell R310 server with a Broadcom BCM5716. The onboard NIC is causing the boot to hang for some reason. Welcome to CentOS Linux Starting udev: udev: starting ...
4
votes
2answers
10k views

What is my NIC ID?

I need to get my NIC ID for a temporarily software license to be generated for me. How should I find my NIC ID? I have found contradictory information on the web. Some suggested that I run getmac.exe:...
4
votes
6answers
6k views

How do I point my browser to a specific NIC on my machine

I am on a local area network that has no external access to the internet. However I have been tasked to find a way to allow certain machines to access the web (HTTP, HTTPS, etc) via a wireless card ...
4
votes
3answers
7k views

Why is ethtool not showing me all the properties for a NIC?

CentOS 5.8 | VMWare ESX 5.1 When I run ethtool eth0 I see the following: [root@foo ~]# ethtool eth0 Settings for eth0: Current message level: 0x00000007 (7) Link detected: yes ...
4
votes
1answer
4k views

Can I create a virtual internal network for my virtual machines in ESXi without using a physical nic?

Using ESXi 4.1 Want my Virtual Machines to be able to communicate with each other, share files, etc. I have 2 nics that go from the server to the network (one public and one private) however these ...
4
votes
2answers
8k views

NIC Active/Passive bonding with priority

I will configure a bond of three NIC's. I want to define which one will be first used and which NIC will be used as the second and third NIC when failover is done. Is this possible? Thanks
4
votes
2answers
5k views

Dedicate a NIC to a Virtualbox VM

On a machine with multiple NICs, running either Windows or Linux, is it possible to dedicate a NIC to a VM such that the host won't even try to use it for itself? I suspect it isn't even possible but ...
4
votes
1answer
200 views

NIC reporting as devXXXX and not ethX

We recently noticed our 10gE NIC was reporting as devXXXXX. Does anyone know why this would be given this name as opposed to ethX? Our System: The issue occurred on two separate servers. We are ...
4
votes
2answers
2k views

Using DHCP with Multi-Homed NICs

I am trying to steer away from our current manual addressing system and embrace the decades-old wonder of DHCP. In our domain and even at my home network DHCP is great - I can use address reservations ...
4
votes
4answers
7k views

Finding NIC firmware version

I need to find out the firmware version of the NIC(s) on on IBM Windows Server 2008 using CMD, Powershell or by any other means.I also should note that I can't reboot the server to go to bios or use ...
4
votes
1answer
4k views

In Icinga (Nagios), how do I configure hosts with multiple IPs?

I'm setting up Icinga (Nagios fork) and I have some machines with multiple interfaces. Some services are only listening on one of them and to check them correctly, I like to know if it's possible to ...
4
votes
2answers
133 views

dual interface NIC with hw bridging?

I'm looking for a PCI NIC with two PHYs that is capable of bridging/switching in hardware but allows the host to monitor the traffic. Does such a thing exist? This would be running on a linux host. ...
4
votes
1answer
1k views

Windows Server 2012 after restart public network become private

I have a 3 servers with Windows Server 2012. After restart one server : public network become private and private network become public. (2 NIC) I don't know how this can happen and how to fix it ? I ...
4
votes
3answers
6k views

Why did robocopy cause my Windows 2012 server to hang last night?

I'm in the process of decommissioning an old 2003 server, which acts as a file server, and am just attempting a dry-run of migrating the file repository over to a new Windows Storage Server 2012 box. ...
3
votes
7answers
5k views

4 NICs or 4-port NIC?

I want to setup a firewall handling two ISP connections and two routers. For that I am planning to use an old Pentium 3 machine. Now, should I use four network interface cards or a 4-port NIC? Do ...
3
votes
2answers
774 views

Are transceivers hot swappable?

Are transceivers in general hot swappable, and if not, how do I find out if these are? Using these adapters 665243-B21, HP Ethernet 10Gb 2-port 560FLR-SFP+ 665249-B21, HP Ethernet 10Gb 2-port 560SFP+...
3
votes
1answer
4k views

Multiple NICs with static IP address, default gateway problems

My server is running Ubuntu 10.04 64bit and have 2 NICs, my configuration is one interface for incoming/outgoing traffic of all the KVM guest running on this server, the other interface for different ...
3
votes
4answers
2k views

Change all network cards to auto/auto on many machines

Because of a change in networking equipment I might need to set a bunch of machines NICs back to auto negotiate. What's the best way to automate this? I'm thinking an Autoit compiled exe pushed out ...
3
votes
3answers
2k views

Cisco SG 300-28P PoE switch appears to have damaged my domain server's network IF

I just replaced the old HP ProCurve switch with a new Cisco SG 300-28P managed switch. It has PoE on all ports. Everything works, except for my domain server that went offline and the network ...