VLANs on Linux (Linux Journal)

Posted Mar 12, 2004 1:19 UTC (Fri) by gerdesj (subscriber, #5446)
Parent article: VLANs on Linux (Linux Journal)

VLANs are extremely handy - sort of.

If you have to deal with the nonsense that is MS Win, have a routed network and no domain (AD) then they are a God send.

If you have a routed network that does'nt support multicast, then hey, fake it with VLANs, eg SLP.

... and many other <sarcastic> examples </sarcastic>.

I have been using VLANs (802.1Q etc) to get around snags that should never arise for around four years now. Yes it can be "handy" to get a box to appear on all LANs on one NIC but it isn't the right way as far as I can see.

Despite this I am extremely gratefull to Ben Greer et al for their efforts in knocking up what was for me a killer app at the time. That code saved me a lot of heartache and around 5000 Win PCs from not having a virus checker reliably installed, apart from anything else. Then there is the ability to broadcast ping several networks from one box.

Mr Greer's code was extremely reliable, considering that the best I could find anywhere else at the time was a 3Com 3c97(8?) "server NIC" at £800 (around USD1500). The 3Com thing was horrible and my PC needed re-booting regularly, also I had to set things up in such away that packets in the size range 1496-1500 got dropped. That was a Win NT then 2000 box. A Linux box with a 3C905A and Mr Greer's code never dropped a packet and just worked - at one stage I had 15 separate Samba's (one for each VLAN) running for a laugh.

So, apart from frustrated server admins with dodgy network hardware (and network admins) and people who don't want to put 30 odd NICs into a network monitoring box -

***** what have VLAN's really done for us? *****

VLANs on Linux (Linux Journal)

Posted Mar 12, 2004 15:59 UTC (Fri) by JohnBell (guest, #12625) [Link]

VLANs are great for move/add/change work. The ability to eliminate physical repatching alone is a godsend.

If you've ever handled a campus area network you'll know what I'm talking about. Repatching cables, and dropping in separate uplinks and pieces of equipment so participation in certain subnets is possible, does not scale in such an environment.

Think in terms of large, dynamic networks (building moves, department moves, etc.).

VLANs on Linux (Linux Journal)

Posted Mar 24, 2004 1:28 UTC (Wed) by gavino (guest, #16214) [Link]

In reply to "what have VLANs done for us?"

I run a computer training company with currently 7 rooms of PCs. Each room needs access to a DHCP server and access to the Internet. Each room has to be totally seperate from one another. This is because in the trainingrooms everyone runs as Administrator and with no password, for ease of Administration. This is a training environment, not a production environment so this is OK. The manchines get re-ghosted at least once a week.

OK. So with VLANs we can use one layer-3 backbone switch and we can have one DHCP server servicing all VLANs, and we can have one interface on our router which can provide Internet access for all VLANs. VLANS means we don't have to have a seperate DHCP server in each room, or a seperate router for each room, nor have a single router but with serveral physical interfaces. VLANs are great!