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Questions tagged [nic]

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

642 questions
54
votes
6 answers

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 forward packets from eth0 to eth1. I have…
Kyle Coots
  • 2,285
49
votes
9 answers

How fast is 127.0.0.1?

I wonder if it is tied to my NIC at all or if the OS or driver intercepts and immediately returns data sent to the loopback address? Does the signal actually travel to my NIC then the NIC returns it?
user55029
48
votes
8 answers

Can a single network card have 2 IP addresses?

Are network cards and IP addresses a one-one map?
kernel
  • 8,861
45
votes
3 answers

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.
rjmoggach
  • 1,063
23
votes
10 answers

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 reasons?
noctonura
  • 463
23
votes
11 answers

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 IP address changes with the last IP entered in the…
Cédric Boivin
  • 744
20
votes
5 answers

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 255.255.0.0 ifconfig eth3 192.168.123.3 netmask…
frustrated_tester
  • 203
18
votes
5 answers

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, Broadcom 5709 Gigabit NIC hardware (MSI-X), with dual…
Wim Kerkhoff
  • 911
17
votes
3 answers

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 googled this question and this seems quite…
gmemon
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17
votes
2 answers

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 for example, given a linear falloff. A 1 GBit per…
Kyle Brandt
  • 85,693
16
votes
1 answer

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/event when NIC should pass the "glued segments" to the…
user2138912
  • 642
15
votes
4 answers

Hyper-V cannot ping VM from host

I have a small Hyper-V environment, but since today I cannot ping from the VM to outside, and not from the local network to the VM. My situation/network in short: Router: 192.168.1.254 My Hyper-V Host/Computer: 192.168.1.10 My Virtual Machine:…
Dennis
  • 756
15
votes
2 answers

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 /var/log/kern.log message: Mar 30 06:32:45 aurora…
Miloš Đakonović
  • 722
12
votes
1 answer

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 guest VM(all private IP). How do I do…
Bin S
  • 123
12
votes
1 answer

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 explains the difference closer to linux kernel…
user2138912
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