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

learn more… | top users | synonyms

3
votes
3answers
10k views

What are the differences between channel bonding modes in Linux?

Under Linux you can combine multiple network interfaces into a "bonded" network interface to provide failover. But there are several modes, some of which do not require switch support. I'm not ...
-4
votes
2answers
127 views

What is the fastest way to connect two machines for a ping-pong test? [closed]

I need to do a latency test between two machines, basically a ping-pong packet test. I wonder what is the fastest connection I can have between those two machines. I imagine my options are: Ethernet ...
3
votes
2answers
2k views

Why is the link between my switch and my router always negotiating half-duplex mode?

I have a Cisco 2950 switch which has one of its ports connected to an Internet router provided by my ISP; I have no access to the router configuration, but I manage the switch. If I leave all switch ...
-1
votes
1answer
114 views

What would cause a wired vs wireless speed difference of 16mbps vs 9 mbps? [closed]

Tested via speedtest.net I've set my wireless router to be b/g/n mode (there's no n-only mode on my router). And I am using a USB stick (N, not G) on on PC and an internal wireless on another ...
0
votes
3answers
493 views

Bonding: works only for download

I would like to install bonding with 4 links with mode 4. but only "download/receiving" works with bondig. for transmitting the system chooses one link. ifconfig bond0 Link encap:Ethernet ...
0
votes
2answers
848 views

ifdown em1 Users cannot control this device. Allow users to control em1 device

I want to allow users to control the em1 device in Linux: When I run this command: ifdown em1 em1 is the embedded ethernet card 1, I want the user to be able to turn off the ethernet card. On ...
2
votes
2answers
3k views

Fedora 17 ifconfig eth0 returns an error message, why did linux change eth0 to em1?

I have a fresh install of Fedora 17 installed, 64 bit. Everything works flawlessly, It connects to the internet automatically when I plug in the internet cable. So I'm kind of confused when I ...
7
votes
1answer
4k views

How do I poll the ARP table with an SNMP OID?

When you need to poll the ARP table of a device, conventional wisdom is to use ipNetToMediaPhysAddress or atPhysAddress; however, both of these OIDs are deprecated according to Cisco's documentation. ...
1
vote
2answers
383 views

Is TCP/IP encapsulation MSB or LSB?

Application data sent over TCP experiences multiple encapsulations: The application data is encapsulated within one or many TCP fragments The TCP fragment is encapsulated within one or many IP ...
7
votes
3answers
3k views

How to test/debug bad network wiring?

I recently bought a place already wired with Cat 5E (8 ports, leading to a central closet). However attempting to get link, nothing works. On closer examination, it was obvious that the ends in the ...
8
votes
2answers
1k views

What is the clock frequency inside 10Gb and 100Gb Ethernet cards?

As I understand, a 10Gb Ethernet card is capable of putting 10Gb every second on (say) a fibre optics cable. Now naively, for this to happen in hardware, one will need a 10GHz clock running the ...
3
votes
1answer
124 views

Two network cards latency

I'm trying to setup a network architecture where one network is a low-latency low-bandwidth tcp control system (GBit), the other is a high-bandwidth udp (maybe tcp) network that could get saturated ...
0
votes
1answer
445 views

arp across subnets which devices can be detected?

i have some devices connected in the same physical network (LAN) but in different subnets. I want to detect them all with the ARP from my computer. My Computer is also in the same physical network but ...
1
vote
1answer
5k views

Can't start eth1 and dhcp on debian wheezy

What I want: eth0 is connected to internet and has a static IP-address. eth1 connected to internal network and be a dhcp server for subnet. But I can't get eth1 to work. Error: $ ifup eth1 ...
5
votes
1answer
1k views

Client not getting address from some DHCP server

I'm working on some embedded devices which should be connected to a large network (hundreds of devices) via ethernet and that should be configured using the DHCP protocol. What I'm experiencing is ...
1
vote
2answers
4k views

Difference between ethernet switch and ethernet pass-through

Most blade server systems can have an ethernet switch module or an ethernet pass-through module. What is the difference between both? Is the pass-though module simply "dumb" as a hub? Why would you ...
1
vote
1answer
804 views

Why is there no autonegotiation for ethernet jumbo frames? [closed]

Having read up a bit about ethernet jumbo frames, I'm wondering. There seem to be technical advantages to being able to use larger than 1500 byte ethernet frames in some cases. Just enabling jumbo ...
2
votes
2answers
4k views

How to test cat5/cat6 cable runs, using software-only, or simple tools?

Are there any utilities or simple tools or techniques to easily test a CAT5 cable, to see how well was it installed? Cat5 is often installed by amateurs, but has been installed and "working" for ...
9
votes
1answer
292 views

LAN: What are the things to look at when arriving in a new place

My company is moving to a new place, and the only thing I know about the cabling is that there are cables and a patch panel. I have no idea about the cable speed, quality, and I'm a software guy with ...
3
votes
1answer
178 views

Server ethernet bridging, fail-safe [closed]

Is there server hardware available with two ethernet ports, that can turn into a fail-safe bridge when offline? My use example is a server that does filtering and traffic monitoring on an ethernet ...
6
votes
1answer
572 views

FCoE, on any Ethernet switch?

I understand the concept of FCoE. I have looked at the Wikipedia page and looking at the layer 2 frame diagram, it looks like FCoE really should "just work" on any Ethernet switch, but is this really ...
0
votes
1answer
229 views

How to setup an Openvpn server with two gateways to internet

I have an openvpn server behind two wan interfaces: eth1 and eth2 where eth1 is the default gw and eth2 is where openvpn binds to. The problems my ovpn server is replying back to ovpn client via the ...
17
votes
2answers
8k views

What is the “in-the-wire” size of a ethernet frame? 1518 or 1542?

According to the table here, it says that MTU = 1500 bytes and that the payload part is 1500 - 42 bytes or 1458 bytes (<- this is actually wrong!). Now on top of that you have to add IPv4 and UDP ...
1
vote
1answer
149 views

Freebsd how detect ethernet loopback on interface

I have network based on stupid hubs. And freebsd router in center of this network. Today i see in 'systat -vmstat' : Interrupts 8005 em1:rx 0 That was a loop on one hub. Is there any way to ...
4
votes
3answers
897 views

Can our firewall detect traffic sniffing inside the network?

We use Cisco ASA's firewall and NAT functions in our network (200 computers). Is there any possibility to configure Cisco ASA to detect traffic sniffering (for example wireshark) and network ...
0
votes
1answer
114 views

Protect software default gateway from ip-stealing

We have a corporate network that is comprised of the following elements: Internet cable (wall) <-> (ext interface (DHCP))(Windows Server 2008, TMG-enabled, Internet Gateway)(int interface (static ...
5
votes
1answer
2k views

Can WireShark detect Ethernet PAUSE packets on network when running on Windows?

We have a Windows server which is connected to a switch processing a large quantity of data. We noticed that when we disabled FlowControl on the network adapter, that it appeared that we were getting ...
0
votes
3answers
4k views

Dell PowerConnect Console connection via Ethernet

When you buy a Dell PowerConnect (In my case it's a 5548) you are given a console cable that is serial to ethernet. Let's say you don't have a serial port on your laptop and but you still want to run ...
0
votes
3answers
176 views

Power-over-Ethernet: Designing PSD with less than 48V?

I want to use Power-over-Ethernet for an IP Camera. On the host-side, which also is the PSE (Power Sourcing Equipment) I have my own hardware. On this hardware I just have 12V of supply voltage. ...
4
votes
2answers
2k views

testing signals on an ethernet cable

I work on escalators that use ethernet cables to send signals from "nodes" to a PLC. the only tool available is a Fluke multimeter. is there a way of reading these signal using the meter? or do I need ...
12
votes
1answer
810 views

How does BER compare between different 10GbE physical media?

I am under the impression that you should use optical for 10GbE networking because of a BER (bit error rate) several orders of magnitude lower than copper. I'm pretty sure I previously found ...
-4
votes
1answer
362 views

What is the minimum and maximum size of an Ethernet frame with split up

How do I calculated the minimum and maximum size of an Ethernet frame with split up.We all know maximum size for Ehternet frame is 1518bytes but would be the with split up?
-2
votes
2answers
173 views

Transparent round-robin scheduling of multiple network interfaces without bonding

I have a server communicating with a cluster of machines and the bottleneck is the network bandwidth. The good news is there are 2 interfaces, while the server can only make use of one. Without ...
2
votes
1answer
999 views

Physical network setup for pfsense w/ CARP for redundant firewalls

So I'm looking at this diagram: http://doc.pfsense.org/index.php/Configuring_pfSense_Hardware_Redundancy_(CARP) Does this assume that the "DSL Router" at the top of the drawing has two physical RJ45 ...
1
vote
2answers
197 views

Power-over-Ethernet: 100 Mbps Device compatible with 1 Gbps Source?

I have an IP Camera, which is supports Power-over-Ethernet. The relating Ethernet Switch on the camera supports 100Mbs. Now when I want to support the camera with Power over Ethernet, will it be ...
3
votes
2answers
3k views

How do I dynamically obtain IP addresses for VLAN interfaces?

I have an Ubuntu machine on which I have created four VLANs, namely eth0.100 ,eth0.200 , eth0.300 and eth0.400. I want to dynamically obtain the IP addresses using the DHCP server. It should provide ...
2
votes
1answer
339 views

PIX Firewall Causing Packet Loss

I am currently in the process of modifying how internet reaches my front end servers and I am having a strange issue with one of the existing stacks. There is one physical firewall which is above the ...
1
vote
2answers
2k views

interrupt coalescing for high bandwidth packet capture?

I have an application which does packet capture from an ethernet card. Once in a while we see packets dropped (we suspect due to the buffer in the network card or kernel being overrun). I am trying ...
0
votes
1answer
472 views

CAT5e RJ45 splitter with CAT6 network: compatibility & performance

I need to connect 2 PCs on a single RJ45 socket on the wall. The network is wired with CAT6 cables. I have seen a few RJ45 splitters that seem to do just that, but they are all for CAT5e cables. Here ...
0
votes
2answers
114 views

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
votes
1answer
799 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 ...
4
votes
5answers
8k 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 ...
1
vote
3answers
475 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 ...
14
votes
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 ...
1
vote
2answers
401 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 ...
1
vote
3answers
734 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 ...
-1
votes
2answers
593 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, ...
-4
votes
1answer
851 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?
0
votes
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 ...
-1
votes
2answers
512 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 ...