Questions tagged [vlan]

Group of hosts with a common set of requirements connected as if on the same broadcast domain despite physical location

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127
votes
2answers
124k views

How do VLANs work?

What are VLANs? What problems do they solve? I'm helping a friend learn basic networking, as he's just become the sole sysadmin at a small company. I've been pointing him at various questions/answers ...
23
votes
7answers
21k views

How many VLANs are too few and too many?

We're currently running a netwok of 800+ PCs and 20+ servers, the network infrastucture is along the lines of Core Switch 10Gb-> Area Switch 2GB-> Local Switch 1GB-> Desktop. All running 3Com ...
13
votes
4answers
56k views

Best way to segment traffic, VLAN or subnet?

We have a medium-sized network of around 200 nodes and are currently in the process of replacing old daisy-chained switches with stack-able or chassis style switches. Right now, our network is broken ...
6
votes
3answers
26k views

DHCP server for multilple VLANs [duplicate]

Possible Duplicate: Can I have multiple DHCP servers on one network? This is a very old question i guess.In this forum itself it has been answered in Multiple VLANs, multiple subnets, single DHCP ...
17
votes
3answers
73k views

Duplicate MAC address on the same LAN possible?

Let's say someone is on the same network as me and spoofs their MAC address to match mine: Is this possible? Can two or more clients with the same MAC address be on the same network at the same time ...
12
votes
5answers
5k views

tc u32 — how to match L2 protocols in recent kernels?

I have a nice shaper, with hashed filtering, built at a linux bridge. In short, br0 connects external and internal physical interfaces, VLAN tagged packets are bridged "transparently" (I mean, no VLAN ...
15
votes
1answer
44k views

VLAN tags not shown in packet capture (Linux) via tcpdump

I am adding a tagged VLAN onto eth0: #ip link add link eth0 name eth0.20 type vlan id 20 This results in: #ip link 2: eth0: <BROADCAST,MULTICAST,PROMISC,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast ...
3
votes
2answers
7k 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
1k views

Persistent Network Configuration using KVM and libvirt

Our environment will have a KVM host setup dynamically using kickstart (easy enough). The hard part is dealing with network configuration and keeping VLAN configuration (and possibly bridge/host ...
25
votes
4answers
14k views

Why do people tell me not to use VLANs for security?

As per title, why do people tell me not to use VLANs for security purposes? I have a network, where a have a couple of VLANS. There is a firewall between the 2 VLANs. I am using HP Procurve switches ...
12
votes
2answers
40k views

Multiple VLANs, multiple subnets, single DHCP server?

At my job we are prepping to transition from multiple LANs connected over slow VPN connections to a single MAN connected over fiber, and I've got a few questions. First of all, we are planning on ...
8
votes
1answer
8k views

Send trunk directly to vm in HyperV 2012

I'm setting up OpenBSD as a VM in HyperV 2012. It would be easier for me to just create one interface on the vm and have OpenBSD take care of setting up the vlans. Is it possible to tell HyperV to ...
8
votes
2answers
10k views

VLAN for WiFi traffic separation (new to VLANing)

I run a school network with switches in different departments. All is routed through to a central switch to access the servers. I would like to install WiFi access points in the different departments ...
3
votes
2answers
8k views

Debian: Should I add vlan interface into bridge for KVM?

I am setting up a Debian Squeeze box as a KVM host. I want to add multiple interfaces to each KVM guest so I want them to be on different VLANs. After reading about this, I believe the best method is ...
8
votes
3answers
3k views

VLAN's - Planning?

Our network is a flat L2. At some point we need to (I want to, but it's not strictly my responsibility) start to VLAN it down as we're obviously going to have a lot of broadcast chatter going on, and ...
4
votes
3answers
15k views

Set 802.1Q tagged port on VLAN1 on Dell PowerConnect switch

I'm having big troubles when adding this Dell switch to my network. Here we use several VLANs to segment traffic. All switches (3com and DLink mostly) have configured the same VLANs, most ports are '...
2
votes
1answer
6k views

How do I setup routing for two companies with different Internet connections on the same LAN?

Here's the setup: Two companies (A & B) share office space and a LAN. A 2nd ISP is brought in and company A wants its own Internet connection (ISP A) and company B wants its own Internet ...
1
vote
1answer
2k views

CoreOS bare-metal vlan networking

I need to write a CoreOS Cloud Config file in which I need to setup networking. But i have a problem because I have a bit weird environment. What I'm trying to accomplish; I have a Sophos UTM thats ...
5
votes
3answers
1k views

Campus VLAN Segmentation - By OS?

We've been thinking through re-arranging our network and VLAN configuration. Here's the situation. We already have our servers, VoIP phones, and printers on their own VLANs, but our problem lies with ...
2
votes
2answers
13k views

How to interconnect 2 switches (Cisco/Dell) with trunks

In order to migrate to a new rack inside the datacenter I have to replicate the VLAN setup between a Cisco Switch and a Dell PowerConnect Swithch. On the Dell Switch I have 2 VLANs : vlan 10 : WAN ...
1
vote
2answers
5k views

Bridging a vlan and OpenVPN tap on Debian

Under Debian I need to bridge a vlan eth0.1 and tap tap0. Usually, when bridging a normal ethernet adapter with a tap I would include something along the lines of this in /etc/network/interfaces: ...
1
vote
1answer
151 views

Routing based on the source ip

I'm trying to configure a host in a way that the traffic is routed either via eth0 or vlan123@eth0, depending on the source address used. Both interfaces have access to the whole network and both have ...
0
votes
1answer
176 views

Cisco 877 ISR - Joining to another local network

At a remote site I have a Cisco 877 ISR providing network services (DHCP, DNS, internet, VPN back to base). I need to connect it to another companies LAN at the remote site to allow uses to print on ...
0
votes
2answers
2k views

Switch sending DHCP packets to wrong VLAN

I have a basic remote site with a Cisco Catalyst 2924XL switch. There are 2 VLAN's at the site: 1 Default 2 Wireless There is a single server connected via a single ethernet cable, VLAN 1 is native/...
3
votes
1answer
5k views

For VLANs: difference between untagged and non-member setting for ports?

The "default" VLAN is VLAN 1, and traffic over ports are Untagged by default (at least, in the switches that we use). We've created VLAN 2 and marked the necessary ports as Tagged, and it's working ...
3
votes
2answers
1k views

One big subnet with all clients an issue?

Disclaimer: Network rookie, might have wrong assumptions. Got a basic subnet question that im interested in hearing your thoughts about. Subnet: 192.168.251.0/24 Address Range for servers: 192.168....
2
votes
1answer
4k views

D-link DAP-2590 VLAN configuration

So we have been fighting this issue for well over a year. It's been so long that I am having to relearn the configuration today. Here's the situation. We're running several D-Link DAP-2590's with ...
2
votes
2answers
3k views

Draytek 2830, Multiple VLANS on Same Port

The Kit Ubiquiti Unifi Long Range Wireless Access Point Cisco SG200-08P Switch (VLAN, POE Support) Draytek 2830VN Router The Problem I need to enable Multiple VLANS against a single port on the ...
2
votes
2answers
2k views

Is it possible to configure a private VLAN on a switch and still access each server via a public IP?

I'm sure this is a very basic/common networking problem. I have 1 web server and 2 database servers that are co-located in a data-center. I have been issued 10 public IP addresses and I have a 10 port ...
2
votes
1answer
449 views

Tagged Packets on native VLAN General Port

Scenario a) I have a Switchport (g1) in General-Mode. Say g1 is member of VLAN1 (native, untagged) and VLAN2 (tagged). Another Port (g2) is in Trunk-Mode, and member of VLAN1 and VLAN2 If i send a ...
2
votes
1answer
1k views

Managed switch port-based DHCP allocation - general case?

I saw a strange comment bagging IT departments (i.e. sysadmins) on Slashdot the other day: half the time they cant even do a simple thing like provide a jack with a set IP address for us Reading ...
2
votes
0answers
514 views

802.1q VLAN echo replies do not include VLAN ID

I am running a SLES11, SP4 kernel on 2 systems. I have 2 NICs connected through a Netgear GS724T switch. I have configured VLAN 400 on the switch. On system 1, I create a VLAN 400 on eth0 called ...
2
votes
3answers
4k views

Linux is sending ARP requests to hosts in other subnets?

Setup Host B <--> Router <--> Host A Host A: IP = 192.168.1.10, Net = 192.168.1.0/24, VLAN = 1, Default GW = 192.168.1.1 (Router) Host B: IP = 192.168.2.10, Net = 192.168.2.0/24, VLAN = ...
1
vote
1answer
1k views

How to share multicast traffic to many vlans

I have linux computer , this computer connected with entire my network via zyxel gs-2200. In this zyxel also connected router with 500 vlans, one by client. On linux computer i have vlc program ...
1
vote
2answers
115 views

VLAN sending data to ports it shouldnt have to

I noticed (based on activity lights) that VLAN traffic between two switch ports are being sent to many switch ports. Here's my scenario: Port 1 is a "mode access" switchport for VLAN 100 (untagged ...
1
vote
1answer
380 views

systemd-networkd fails to run DHCPServer on trunk port with multiple VLAN interfaces

I'm trying to configure a Linux host running systemd-networkd on a switch trunk port. The host has a single interface, enp4s0. There are only a couple VLAN ports in the switch, others are untagged. I ...
1
vote
0answers
195 views

Small business network vlans and hyper-v configuration

We are a small business and have been successfully running one Hyper-V 2012 R2 vmhost with many Windows Server 2012 VMS that includes a DC, Web Server, CRM Server and SQL Server for a couple of years. ...
1
vote
1answer
5k views

Cross-VLAN sharing and auto-discovery of selective resources

I have a network with several VLANs that each contain resources or clients with different access rights. For simplicity, let's say I have 3 VLANs: ID 10: Contains privileged clients and private ...
1
vote
1answer
1k views

KVM Windows Guest Vlan Tagging

Right now, I'm trying a new cloud provider which facilitates private networking, this is a feature on which you can run multiple vlan's. Because the platform that we are going to build is a linux/...
1
vote
0answers
181 views

VLANS and Public/Private Traffic

I may reveal some ignorance with this question, but I am really confused. We have 3 static IPs and one gateway/modem with my organization. The gateway/modem is located in a remote area of our building,...
0
votes
1answer
52 views

Route 2 VLANs over one port

Related to, but expended on an earlier question of mine at Route all traffic over Fiber VLAN The fiber internet works nicely, this is the setup; Media Converter | +--- Ubuntu Server ...
0
votes
1answer
39 views

Route all traffic over Fiber VLAN

Recently, I upgraded to fiber based internet, that works okay but I want to hook that up directly to my Ubuntu box instead of the supplied router. The problem is, even though I can get a valid IP via ...
0
votes
2answers
918 views

Two IP address on one network adapter over macvlan

On Debian Linux dist I need two IP address with different mac address. On each of them one server will run on port 80. So i need something like this: ip: 192.168.2.1 mac: xx:xx:xx:10:xx:xx ip: 192....
0
votes
2answers
1k views

Enabling 8021q on a nic

I'm trying to get a vlan interface on a bonded nic (Centos 5.5) and whilst the interface has been very happily created with vconfig I'm seeing no traffic on it at all. Running tcpdump and tshark on ...
0
votes
1answer
8k views

Draytek Vigor 2860 multiple external IP-addresses

I've bought a DrayTek Vigor 2860 for my company network. And I'd like to use it for two VLANs with separated external IP's. I have 6 LAN ports on my DrayTek. For example: External IP-adres: 201.102....
0
votes
1answer
2k views

Broadcast between VLANs

I have a network with 2 VLANs running on a Cisco SGE2010 with the switch acting as the gateway for each vlan: 192.168.10.0/24 VLAN 10 192.168.20.0/24 VLAN 20 Servers live on VLAN 10 and Desktops on ...