Iptables and vlan interfaces
aseem at india.tejasnetworks.com
Mon Oct 3 12:05:11 CEST 2005
Does it mean that if I connect my machine ethernet port to another
machine and configure a vlan interface with that port as physical port
and then add route to another machine through that vlan interface (I
need to do this to use vlan interface right ? ), then all packets sent
out of it will be tagged by whatever tag i mention in vconfig?
I did't know about vlan support in linux. This can be a good testing
platform for L2 applications without requiring special boxes.
Henrik Nordstrom wrote:
> On Mon, 3 Oct 2005, Aseem Rastogi wrote:
>> i have been following this post rather keenly. it now seems to have
>> died down. but still i am not able to understand what is a vlan
> VLANs is IEEE 802.1Q, dividing Ethernet into 4097 virtual Ethernet
> networks. (the normal untagged network + 4096 .1q tagged networks = 4097)
> VLAN is normally only used within and between switches, but it is also
> possible to use between the switch and a server/host allowing the
> server to participate in multiple VLANs on the switch.
> This is configured on the Linux side using vconfig, creating one
> vritual network interface per such virtual Ethernet being used between
> the server and the switch. The virtual interfaces created by vconfig
> is true virtual interfaces and can even have a different MAC address
> than the physical interface if you like (defaults to use the same MAC
> however). These virtual interfaces is named like
> physicalinterface.vlannumber (i.e. eth0.45 for the VLAN with the .1q
> tag 45 on the eth0 physical connection).
> More information on the VLAN support in Linux can be found from
> http://www.candelatech.com/~greear/vlan.html. The needed software is
> also available in most distributions (the kernel driver is available
> in the kernel since many years back). \
>> can somebody please give me some pointer where i can read about this.
>> vlan i thought is a l2 concept and should have nothing to do with l3.
> vlan is indeed purely a l2 concept, using a slightly different
> Ethernet frame format than normal Ethernet allowing for multiple
> virtual Ethernet networks to be transported over the same cable.
> IP-aliases on the other hand is purely a l3 concept, allowing you to
> have more than one IP address on the same interface, optionally
> labelled with a name (interface:name) for administrative purposes. The
> (optional) label on an IP-alias has no significant meaning other than
> as a reminder to the administrator, and to produce confusing results
> when using ifconfig (ifconfig has the odd habit of displaying the
> named ip-aliases as if they were separate interfaces).
The end is always good. If it's not good, it's not the end.
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