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

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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 ...
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2answers
6k 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 ...
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1answer
132 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 ...
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3answers
762 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 ...
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1answer
98 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 ...
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1answer
1k 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 ...
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3answers
3k 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 ...
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3answers
151 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. ...
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2answers
1k 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 ...
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1answer
654 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 ...
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212 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?
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572 views

Trying to make USB-to-Ethernet adapter work on CentOS 5

I have a SR9600 USB-to-Ethernet adapter and, when plugging it on a Dell server running CentOS 5, the lsusb listing doesn't even change -- nothing at all appears in dmesg. But the USB port on that ...
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156 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
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1answer
813 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 ...
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2answers
184 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 ...
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2answers
2k 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 ...
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1answer
305 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 ...
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2answers
1k 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 ...
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1answer
398 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 ...
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2answers
102 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
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1answer
600 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
6k 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
432 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
369 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
603 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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505 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
676 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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3k 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
383 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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1answer
403 views

Good reference for Cisco Resilient Ethernet Protocol [closed]

I have been trying to understand Cisco's Resilient Ethernet Protocol, but am unable to find a proper source to read from. I checked the Cisco site and also their White Paper on REP. But none of ...
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2answers
486 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
1k 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
6k 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
399 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 ...
4
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1answer
4k 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
443 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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466 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. ...
7
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1answer
654 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
498 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
132 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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117 views

How to pervent vtp updates coming from vmware to go towards switch?

To get the background of this question please follow this link http://security.stackexchange.com/questions/14803/using-nessus-an-alien-packet-from-switch-shut-down-my-ethernet-card-completely I have ...
2
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1answer
833 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 ...
2
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1answer
477 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
73 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
177 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
313 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
593 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 ...
3
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1answer
949 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 ...