set_name_type, WAS RE: NEWBIE: RH Linux and ProCurve VLAN Setup

On Thu, 5 Jan 2006, Duane Mulder wrote:

> Hello Eric:
>
> Some HP procurves only support 30 VLANS tagged from 0-30. Silly but true. We
> have a procurve that is like that. So when you setting up your Vlan
> interfaces you will need to keep the VLAN tag number below that.
>
> So you would do something like this
> vconfig set_name_type VLAN_PLUS_VID_NO_PAD (The first line setup the nameing
> convetion)
> vconfig add eth1 6    				 (or eth0) and choose vlans
<snip>

For (possibly ancient) reasons I've always used DEV_PLUS_VID_NO_PAD 
meself, but I just realised that some of my scripts don't explcitly set it 
at all (so might see problems if/when the defaults changed).

While playing with this I accidentally did:

# just to test you understand...
vconfig set_name_type VLAN_PLUS_VID_NO_PAD
vconfig add eth1 576
vconfig add eth0 576

and ended up with /proc/net/vlan/config showing:

$ cat /proc/net/vlan/config
VLAN Dev name    | VLAN ID
Name-Type: VLAN_NAME_TYPE_PLUS_VID_NO_PAD
eth0.2         | 2  | eth0
eth0.4         | 4  | eth0
eth0.551       | 551  | eth0
vlan576        | 576  | eth0
eth0.832       | 832  | eth0
eth0.833       | 833  | eth0
vlan576        | 576  | eth1

Having realised that creating 2 vlan576's was probably why I didn't use 
this name-style, I tried to remove them and got:

$ vconfig rem vlan576
Removed VLAN -:vlan576:-
$ vconfig rem vlan576
ERROR: trying to remove VLAN -:vlan576:- error: Invalid argument

$ cat /proc/net/vlan/config
VLAN Dev name    | VLAN ID
Name-Type: VLAN_NAME_TYPE_PLUS_VID_NO_PAD
eth0.2         | 2  | eth0
eth0.4         | 4  | eth0
eth0.551       | 551  | eth0
eth0.832       | 832  | eth0
eth0.833       | 833  | eth0
vlan576        | 576  | eth1

Oops it is still there but can't be removed.  It doesn't show up with:

  ip link show

though...

I'm not sure if this is a bug in vconfig or the dot1q module or just in my 
limited understanding of it.  Anyway I'm back to using DEV_PLUS_VID_NO_PAD 
for now...  Or maybe this is just a problem with the code in the RHEL-3
kernel/vconfig which was already corrected in more recent versions.

In any case one can _always_ trivially change the names (just after) 
creation if you don't like the style, e.g.

$ vconfig add eth0 576
Added VLAN with VID == 576 to IF -:eth0:-
$ ip link set eth0.576 name eth0.vl.serv
$ ip link
...
19: eth0.vl.serv: <BROADCAST,MULTICAST,PROMISC> mtu 1500 qdisc noop
     link/ether 00:09:5b:bd:a4:e5 brd ff:ff:ff:ff:ff:ff

if one prefers more memorable names (15 char limit on interface 
names though!)

  -- Jon