Jason McIntyre <j...@kerhand.co.uk> wrote:

> whereas /etc/netstart is actually doing:
> 
> - configure non-physical:                           (1)
> aggr trunk svlan vlan carp pppoe
> - routing                                           (2)
> - rest of non-physical:                             (3)
> tun tap gif etherip gre egre mobileip pflow wg
> 
> we could try to keep this list up to date, but it may be easier to just
> generally describe what netstart is doing.

I think we goes wrong by trying to maintain these as lists, and part of
where this goes wrong is weak definition of the reasons for the
ordering.  (Meaning, the developers who tweak netstart to handle the
concerns I'm about to describe, don't tend to think about the manual
page).

The (1) list of non-physical can probably be called "link-layer control
interfaces".  Or let's find a name for this.  These devices mutate the
presentation of other devices.  That's why their configuration needs to
be done before the physical device.

(2) The physical device is then brought up, including IP addressing. The
things in (1) need to be done beforehands, or the physical device is
participating in the wrong layer of network.

the (3) list of non-physical devices are layer-2 or layer-3 and operate
on devices which are already configured with some some sort of
"addressing" configured.

It would be nice to have our networking people come up with nice names
for group (1) and (2); words which succinctly describe the
classification like I've done above.  We need to increase understanding
of this order, rather than just abstractly listing names of devices with
complicated behaviours.

Once that is done, I still think it is problematic for us to list all
devices in each catagory:

a) new subsystems will be forgotten
b) the order of instantiation will sometimes be listed wrong -- for some
   of these the order is highly significant.

We can try to list as many as possible, but people who want the precise
list (and order) should look in the netstart code.  The lists will get
long and wrong.  If we find we cannot maintain the lists correctly
because it is duplicated information, man page wording like "such as"
could be used, also something which leads people to consider the script
source as authoritative, ie. have them go read the script 

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