[LARTC] First Post: Question on Ip Aliasing

[LARTC] First Post: Question on Ip Aliasing

[Discussion Lists]

Hi All,
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
TC/iproute2/HTB will behave like that: Meaning, are they supposed to
throttle bandwidth for the physical, AND the alias at the same time, or
do I need a separate rule?

Thanks in advance!

P.S.
I tried setting up eth0:0 as a config file in the HTB dir, and htb.init
didn't like that at all.  I wonder if TC would react the same way?
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Re: [LARTC] First Post: Question on Ip Aliasing

[Jose Luis Domingo Lopez]

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

[Discussion Lists]

Thank you for your response.  You confirmed what I understood to be how
it works, but for some reason it isn't working like that, and I can't
understand why.  The alias gets assigned through heartbeat, during a
failover, but traffic routes through that alias as if there was no
shaping going on at all.  In other words it just isn't working the way
that it should be working.  I am not even sure where to look for
problems or errors.  I don't see how my configuration can be wrong
because it is shaping traffic just fine on the physical adapter . .. If
anyone can think of other suggestions, I would greatly appreciate it.

Thanks!

> -----Original Message-----
> From: Jose Luis Domingo Lopez [mailto:lartc@24x7linux.com] 
> Sent: Thursday, April 08, 2004 8:12 AM
> To: lartc@mailman.ds9a.nl
> Subject: Re: [LARTC] First Post: Question on Ip Aliasing
> 
> 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)
> _______________________________________________
> LARTC mailing list / LARTC@mailman.ds9a.nl 
> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
> 
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RE: [LARTC] First Post: Question on Ip Aliasing

[Daniel Chemko]

Discussion Lists wrote:
> Thank you for your response.  You confirmed what I understood to be
> how it works, but for some reason it isn't working like that, and I
> can't understand why.  The alias gets assigned through heartbeat,
> during a failover, but traffic routes through that alias as if there
> was no shaping going on at all.  In other words it just isn't working
> the way that it should be working.  I am not even sure where to look
> for problems or errors.  I don't see how my configuration can be
> wrong because it is shaping traffic just fine on the physical adapter
> . .. If anyone can think of other suggestions, I would greatly
> appreciate it.         

Do you run the trafficing script during a failover, or just when you
boot the system? Maybe the traffic routing rules get dropped from the
system once the interface is down, much the same way that routes do?
Just a thought. I haven't bothered to setup traffic rules on my gateways
yet.
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Re: [LARTC] First Post: Question on Ip Aliasing

[Roy]

nothing can go out through alias inetrface, alias is for input only.

so everything is going through physical interface like eth0
if you are forwarding packets, then your interface ip is ignored anyway.
(it is only used to translate ip to mac)
if you want to shape localy generated trafic, then source ip will depend on
what the user will chose,
since he can use any aliased ip of your server.

so simply ignore all virtual interaces imagine that you have none of them,


----- Original Message ----- 
From: "Discussion Lists" <discussions@lagraphico.com>
To: <lartc@mailman.ds9a.nl>
Sent: Thursday, April 08, 2004 11:59 PM
Subject: RE: [LARTC] First Post: Question on Ip Aliasing


Thank you for your response.  You confirmed what I understood
to be how
it works, but for some reason it isn't working like that, and I can't
understand why.  The alias gets assigned through heartbeat, during a
failover, but traffic routes through that alias as if there was no
shaping going on at all.  In other words it just isn't working the way
that it should be working.  I am not even sure where to look for
problems or errors.  I don't see how my configuration can be wrong
because it is shaping traffic just fine on the physical adapter . .. If
anyone can think of other suggestions, I would greatly appreciate it.

Thanks!

> -----Original Message-----
> From: Jose Luis Domingo Lopez [mailto:lartc@24x7linux.com]

> Sent: Thursday, April 08, 2004 8:12 AM
> To: lartc@mailman.ds9a.nl
> Subject: Re: [LARTC] First Post: Question on Ip
Aliasing
>
> 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)
> _______________________________________________
> LARTC mailing list / LARTC@mailman.ds9a.nl
> http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/
>
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