1
vote
1answer
35 views

Connect access switches to router or core switch

My workplace consists of 4 access unmanaged network switches from three different computer rooms connected to a router. The router contains three 100mbps ethernet ports and one Gigabit (GigE) port. ...
2
votes
1answer
233 views

Is there a standard managed switch configuration protocol?

is there a vendor-independend managed switch configuration protocol e.g. for creating VLANs that can be run over TCP or serial port?
-2
votes
1answer
99 views

ethernet switch makes network down [closed]

I have a D-Link 8-port Ethernet switch which was perfectly working. Since 2 days ago it makes the entire network down. The problem is when I disconnect the cables it runs again and after I connect ...
2
votes
1answer
455 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 ...
0
votes
1answer
20 views

Why am I seeing prefixed/duplicated packets coming from a comcast device?

I'm looking at traffic my CPE from Comcast in Wireshark, and for every packet, there is an additional packet that is the exact same, except for 4 additional bytes at the beginning of the frame ...
3
votes
2answers
281 views

What does 'Si' mean with respect to network switches?

I am seeing references to Multilayer Switches with Si as in the network symbol below. What does the 'with Si' qualifier mean?
5
votes
3answers
440 views

Gigabit uplink versus regular switch port

I have a 10/100/1000 24-port + 2 mini-GBIC ports switch which I have to link to other switches. Unfortunately, on the other switch all the mini-GBIC slots are taken up, so all I can do is link them ...
1
vote
2answers
77 views

How can I change metric of public network in route table

In my windows 8.1 ENT [64 bit] machine I have 3 network adapters. Ethernet 1 is connected to public network and other 2 ethernet adaptors are connected to different internal networks. The problem is ...
0
votes
0answers
38 views

AR8151 eth0 heavy trouble

First I had really bad issue with network speed. There I got this good article: http://mindmapapp.blogspot.com/2012/01/use-atheros-ar8151-ethernet-card-on.html But now I have really crazy things ...
0
votes
1answer
21 views

Use local Internet connection

I have a network split into through two ethernet segments through a virtual VPN hub. In the figure, blue is the part of the network that I control. My problem is due to the orange subnetwork, that ...
1
vote
1answer
113 views

Network latency caused by incorrect cable?

Our team recently setup a new network and now we are experiencing network latency issues. the flow of traffic is as such: modem -> router -> packet shaper -> cisco3750 switch from router to packet ...
2
votes
1answer
175 views

Full MTU not utilized with jumbo frames enabled

I've been testing to see if I can get any benefit from enabling jumbo frames. I've set up two identical Dell R210 servers with Xeon quad core E3122 CPUs, 8G of RAM and Broadcom NetXtreme II BCM5716 ...
1
vote
2answers
753 views

Connect two networks to a single server using its two ethernet ports

I have two separated local networks (two routers, each is connected to its ISP for the internet connection) and a server with two ethernet ports. The server is running a local website service which I ...
0
votes
0answers
48 views

ZyXel ES-2024 - Mirrored port showing duplicated traffic

I have a ZyXel ES-2024 PWD switch. I would like a computer plugged into port 26 to see all traffic that passes through port 2, both inbound and outbound. I have configured port mirroring for the ...
0
votes
1answer
157 views

Restrict network connection to virtual machine alone-VMWare

Is there a way to restrict a Ethernet/Wifi Connection to the virtual machine alone and not to the host operating system? I am using VMWare workstation on windows with centOS and Ubuntu as my guest OS ...
2
votes
0answers
1k 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 ...
-1
votes
1answer
84 views

Networking service not responding [closed]

Networking is going down on some of our machines. This is happening very randomly. Restarting networking is fixing the issue. I found the following in the kernel logs: Mar 19 18:19:05 <host> ...
0
votes
2answers
395 views

Connecting VoIP Phones to a Laptop

I'm trying to connect two VoIP phones to a laptop using the internal ethernet adapter and a usb-to-ethernet adapter. My configurations are as follows: Laptop eth0 - 121.1.2.1/24 Gateway - 121.1.2.4 ...
0
votes
2answers
94 views

Different speed on Internet connection by switching NICs. Can someone make sense of this?

I solved my Internet speed problem, but I'm still puzzled. I can't understand what happened. My scenario: a small intranet is connected to Internet through a Linux gateway that connects to a Cable ...
0
votes
0answers
228 views

VirtualBox VM network hangs due to ethernet “Reset adapter”

I have a VM which I've created on a host using the following settings: http://pastebin.com/raw.php?i=sevF5V7Z It has been up and running smoothly for months but recently the VM lost connection with ...
-1
votes
1answer
400 views

Ethernet Bridging With USB-to-Ethernet Adapter

I have a USB-to-ETHERNET adapter (CP-USB-RJ45M) with which I am trying to create an ethernet bridge in CentOS Linux for ip-forwarding within a private LAN test network. I modified my /etc/rc.local ...
1
vote
0answers
134 views

How can i detect and diagnose local network problems on a multi-server environment?

I'm a software engineer who trying to detect (and solve if possible) weird local networking problems since 2 weeks on multi-server hosting environment. We bought 3 dedicated boxes with 32GB ram 8 ...
0
votes
1answer
113 views

Ethernet is taking very long time to recover after switching loop

Problem generation is very simple like jamming a network without STP ;-) Ok, so steps of creating my problem is given as follows: Ping Device A from Device B. Reply is coming. Generate a network ...
0
votes
1answer
123 views

Unable to set initcwnd on a Hetzner server

We just ordered a bunch of Hetzner EX40SSD servers with the minimal Debian install image that they provide and everything is just fine except that looking at tcpdumps for fine tuning the network from ...
11
votes
5answers
2k views

A “splitter” is plugged into a patch panel… how does this still work?

I found a patch panel that splits off ethernet into multiple hosts as shown below. Can anyone explain how this might work?
-1
votes
2answers
324 views

Ethernet port not detected

I just added additional 1gb port to my existing 4gbs on my server. All 4 are placed on a NET CARD PCIE 1GB E1G44HTBLK 904223 INTEL and the additional one is connected to motherboard(S5520SC) ...
2
votes
1answer
136 views

How does a NIC send a hardware interrupt? [closed]

Some context. A few weeks ago, a NIC was replaced on a box without much troubleshooting to find a clear resolution to the problem. A senior administrator got into a small tiff with an entry-level ...
2
votes
1answer
296 views

Is it ok to use cat5e patches/jacks on cat6a cable for 10Gb

I understand that "technically" you are supposed to use cat6 cable jacks as well as cat6 patch panels. In practice I've seen cat6a plugged into cat5e patch panels, although I've never seen cat5e ...
2
votes
1answer
267 views

How can I stress an Ethernet managed Switch?

for testing purposes I need to stress an 8-port managed ethernet switch. Essentially, I want to simulate a scenario in which two hosts on the switch are exchanging data and the other hosts connected ...
0
votes
3answers
177 views

CentOS Network Interface Priorization

I have a CentOS server with 2 network interfaces with configurations: eth0: DEVICE=eth0 BOOTPROTO=none BROADCAST=10.0.0.255 HWADDR=xx: IPADDR=10.0.0.2 NETMASK=255.255.255.0 NETWORK=10.0.0.0 ...
4
votes
1answer
249 views

Is it possible to use WPA2 over ethernet?

Like, as in requesting a "password" to connect, just wondering. Also, are any of these (VPN, public key auth?) methods either possible or implemented?
1
vote
3answers
2k views

Can Wireshark capture an entire Ethernet frame including preamble, CRC and Interframe spacing?

I am examining an Ethernet frame in Wireshark. According to the "Ethernet frame" Wikipedia article and accompanying diagrams, "A frame starts with a 7-octet preamble and 1-octet start frame delimiter ...
0
votes
2answers
110 views

Switch between network configurations via command line in fedora 17

I have two different setups I use on my work laptop; one enables synergy over an ethernet ssh tunnel with my work computer on the local network, and the other opens an HTTP tunnel to my work computer ...
0
votes
0answers
151 views

bonding - balance-tlb and a mysterious ethernet packet with lots of 00:00:00

Whilst attempting to get bonding working with mode=5 (balance-tlb) it seems that the driver sends an ethernet packet with length 0x0060 and the data, payload is all zeros. I can't work out where this ...
1
vote
2answers
284 views

Tunnel Ethernet Packets over SSH

I have two machines. My laptop and a machine in the local intranet. This machine has next to the network device (for the intranet) a second network card. I want to send raw ethernet frames out of this ...
1
vote
1answer
181 views

Bond0 Failover when link light stays up: High Availability Network

Configuration: Two switches, each with a separate internet route Centos servers with eth0 and eth1 bonded as an active-backup on bond0, eth0 in on switch and eth1 in the other /etc/modprobe.conf ...
0
votes
1answer
441 views

troubleshoot Ethernet (layer 2) without layer 3

I am troubleshooting a LAN and the problem is to make sure each host can reach each other at layer 3. Each host is configured to the same subnet, but some hosts cannot reach other at layer 3 (e.g. ...
1
vote
1answer
39 views

Use or not to use multiple ips on the same network card?

I got a Dell r620 that cames with 4 network interfaces. If I have for example 4 ips, and want to assigne them to the server. What would be better, in terms of performance. Add all the 4 ips to the ...
4
votes
1answer
326 views

command for MAC broadcast

I am looking for a command to discover all hosts on the same LAN segment from a host with unassigned IP, default gateway, and subnet. I know there's ping 255.255.255.255 but that operates at layer 3 ...
3
votes
2answers
295 views

How can I make a secondary NIC port “eth0”?

I am using CentOS 5.9. One of my servers recently had a malfunctioning NIC port. The software running on the server was hard-coded to use eth0. The other physical NIC ports were fine and unused. The ...
4
votes
1answer
174 views

Supress FreeBSD “link down: cable pr╬┐blem?” messages

I have a FreeBSD lab machine that is regularly connected and disconnected from the network, sometimes to borrow the port temporarily for another machine and other times to test the ability of certain ...
2
votes
2answers
220 views

High number of ethernet errors. Tool for testing the ethernet card?

have an Asus Sabertooth X79. I often get corrupted files. I checked the RAM, but memtest finds no errors. To avoid the possibility of disk errors, I tried copying files to tmpfs. If I copy from the ...
0
votes
0answers
86 views

I have a firewall that supports 1Gbit ethernet ports but 1.4Gbit of traffic, can I make use of a 10Gbit pipe from the router in this case?

We're putting up a rack of servers in a datacenter which provides us either a 1Gbit pipe or 10Gbit pipe from the router (our choice, our package includes 10Gbit). But if we have a firewall which ...
5
votes
1answer
214 views

Is it possible to receive dhcpdiscover from ff:ff:ff… mac address?

Today I saw this record in my log files: dhcpd: DHCPDISCOVER from ff:ff:ff:ff:ff:ff via vlan400: network 40.60.100.10/24: no free leases ...
0
votes
0answers
191 views

linux ethernet card ping problems?

I have a very strange problem with my ethernet card. Here is ethernet card details: description: Ethernet interface product: RTL8169 PCI Gigabit Ethernet Controller vendor: Realtek ...
4
votes
1answer
359 views

Is is possible to put a tagged vlan on one physical interface on a Force10 S50N switch?

I servers that have a shared ethernet port for IPMI and the first NIC. They have 4-1GbE nics. I would like to bond the nics via LACP while still being able to access the IPMI over a tagged vlan only ...
0
votes
1answer
159 views

How do I calculate the ethernet NIC-to-NIC time to send a MTU packet (1500 bytes)? (OS-excluded) [closed]

I understand it will depend on the speed of the ethernet 10 Mbit to 100 Gbit. Given an ethernet speed, how do I calculate the time spend in the wire from NIC-to-NIC? I am assuming here that the ...
2
votes
2answers
2k views

How to change 'Advertised pause frame use' and autonegotiation setting on gigabit NIC

I'm investigating some poor nfs performance on a new server, as compared to an old server. Both the old and the new server are nfs clients, and they connect to the same exact NetApp nfs server. My ...
1
vote
1answer
1k views

bridging two network interfaces in ubuntu linux 12.10 AND being able to access it from that machine

Ok, i have about had it but heres the deal. I have 7 total machines connected like this: [5 workstations]<--->ServerPC<---->MAINPC<---->router FYI, dont worry about the workstations they ...
1
vote
2answers
446 views

New EFM leased line setup with Watchguard router, vlan tagging issue

I have recently had a 2mb EFM connection installed in a charity I work for. We were not supplied a router because we already had a watchguard XTM330 in storage ready to be used. The line is presented ...