You are here: Foswiki>ATLAS Web>VLAN (20 Oct 2007, MatthiasLInden)Edit Attach
Category:Network VLANs are described in IEEE 802.1Q.


VLANs are a 4 Byte extension to the standart Ethernet-frame, the VLAN-tag. The Tag is set by the driver of the networkinterface. On most modern switches packets are routed according to VLAN-tags. The configuration is port-based.

The Tag containes a 12bit VLAN-name and a priority. VLAN-names from 1-4095 are valid.


On Linux nodes to send/recive VLAN-tagged packets one has to set up a virtual interface on top of the physical interface. This virtual interface behaves the same way as a physical interface. An IP-address and Netmask has to be set to get the VLAN-interface working. For a VLAN-interface for VLAN 2 on top of eth1 the name of the virtual interface would be eth1.2 .



On the Switch side, every port can be configured to revice tagged packets from every VLAN-number, that has been activated before. Tagged packets are only routed to Switch-ports that are configured to recive packets from the specified VLAN.


In both telnet-menu-mode and on the web interface the VLAN-configuration can be done. Visit HP2900 VLAN configuration



To add a virtual interface for VLAN 10 on top of eth0, first bring eth0 up, otherwise the vconfig add will return an error.
 #ifconfig eth0 up
 #vconfig add eth0 10
The Interface will be named eth0.10.
 #vconfig rem eth0.10
Removes the Interface that has just been created.

Next step would be to configure the virtual VLAN-interface.
 #ifconfig eth0.10  _IP_ netmask  _255.255.x.y_ ...


Topic revision: r1 - 20 Oct 2007, MatthiasLInden
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