Subject: Re: A possible way of handling variant/common devices
To: Andrew Gillham <>
From: Curt Sampson <>
List: tech-kern
Date: 03/28/1997 14:02:07
On Fri, 28 Mar 1997, Andrew Gillham wrote:

> WRT "eth*" devices, they would be useful, especially when/if NetBSD
> decides to implement subinterfaces.... I would love to be able to do
> something like:
> 	ifconfig eth0 x.x.x.1 
> 	ifconfig eth0.1 x.x.x.2
> 	ifconfig eth0.2 x.x.x.3
> etc.. the 'alias' syntax is rather cumbersome.

1. There's no need for both subinterfaces and aliases; as far as
I can tell both do essentially the same thing.

2. Subinterfaces far more cumbersome than the alias interface, for
the following reasons:

a) If you have two hundred or more addresses to add to an interface,
as those of us who run a lot of virtual web servers do, you need
to write more code to do it that the current simple loop of `ifconfig
ed0 alias'.

b) After you've done your intial adds on startup, adding further
IP addresses later is harder because you have to find unused
subinterfaces to add them on, rather than just doing an `ifconfig
ed0 alias'.

c) Deleting an arbitrary IP address is more difficult, becase you
have to find out which subinterface it's on, rather than just daoing
an `ipconfig ed0 delete'.

I really can't see any advantage at all to subinterfaces, and I
can see a lot of disadvantages.


Curt Sampson		Info at
Internet Portal Services, Inc.		`And malt does more than Milton can
Vancouver, BC   (604) 257-9400		 To justify God's ways to man.'