Re: [LARTC] First Post: Question on Ip Aliasing

[Jose Luis Domingo Lopez <lartc@24x7linux.com>]

On Thursday, 08 April 2004, at 06:53:27 -0700,
Discussion Lists wrote:

> I did a google search on this and didn't find exactly what I was looking
> for.  Suppose I have a machine that has an IP alias eth0:0.  I have set
> up HTB.init so that it properly throttles bandwidth on eth0, however
> when I use eth0:0, it doesn't work.  I read elsewhere that it should
> work at the PHYSICAL device layer, and should therefore work for both at
> once.  This is not happening though.  Just wanted to find out if
>
I think that the "hack" of "alias interfaces" in Linux has been one
major source of conceptual problems with respect to Linux routing and
the like in past years :-). I have always believed that it is much
better to think of IP addresses in Linux as assigned to physical
interfaces rather than associated to some kind of a virtual one.

The "ip address show" command shows very clearly this fact. Each
interface has zero or more IP addresses assigned to it, and with "ip"
you will never see "alias interfaces" again, because this tool is modern
enough to understand the fact. I encourage everyone to make the move to
"ip" from old "ifconfig" and related tools as soon as possible.

In the "ip" world you just have physical (or not so physical, like bond?
or VLAN interfaces) interfaces and IP assigned to them. And when you
want to refer to IP addresses, you just use them. And when you want to
refer to interfaces, use the one you need.

Also, have a look at the Stef Coene's excellent KPTD at:
http://www.docum.org/stef.coene/qos/kptd/

Couple the above diagram with the previous explanation about IP and
interfaces and maybe all will now be simpler to you.

Greetings.

-- 
Jose Luis Domingo Lopez
Linux Registered User #189436     Debian Linux Sid (Linux 2.6.5)
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