[LARTC] Shaping Device Aliases

[LARTC] Shaping Device Aliases

[Gordan Bobic]

Hi.

I understand that device aliases (e.g. eth2:3) are not shapeable. Does 
anybody know if this functionality is planned in the future?

Anyway, for the time being the only option that seems to leave is to 
fwmark packets differently for each device alias and then shape based 
on that.

Is it possible to set multiple marks on the packets? Alternatively, is 
it possible to check for a specific bit in a fwmark, and use these are 
individual flags by XOR-ing the fwmark against some mask that is being 
checked for?

Gordan
_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/

Re: [LARTC] Shaping Device Aliases

[Damion de Soto]

Gordan Bobic wrote:

> I understand that device aliases (e.g. eth2:3) are not shapeable. Does 
> anybody know if this functionality is planned in the future?

None of the new(er) networking tools recognise device aliases, because on
all recent linux releases, aliases don't exist.
the ethX:X notation is a legacy notation used only by the ifconfig program.
everything else just sees a ethX with more than one IP address.

So you just run your shaping rules on the real interfaces, and restrict
it's operation with IP address filtering.


-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Damion de Soto - Software Engineer  email:     damion@snapgear.com
SnapGear - A CyberGuard Company ---    ph:         +61 7 3435 2809
  | Custom Embedded Solutions          fax:         +61 7 3891 3630
  | and Security Appliances            web: http://www.snapgear.com
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  ---  Free Embedded Linux Distro at   http://www.snapgear.org  ---

_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/

Re: [LARTC] Shaping Device Aliases

[Gordan Bobic]

On Friday 16 Jan 2004 06:23, Damion de Soto wrote:
> Gordan Bobic wrote:
> > I understand that device aliases (e.g. eth2:3) are not shapeable.
> > Does anybody know if this functionality is planned in the future?
>
> None of the new(er) networking tools recognise device aliases,
> because on all recent linux releases, aliases don't exist.
> the ethX:X notation is a legacy notation used only by the ifconfig
> program. everything else just sees a ethX with more than one IP
> address.
>
> So you just run your shaping rules on the real interfaces, and
> restrict it's operation with IP address filtering.

Yes, I am aware of that. However, that makes shaping multiple 
independent "streams" going through one interface much more difficult.

The only other thing I can think of is setting up a dummy network device 
and giving it the IP addresses on all the non-primary subnets (e.g. 
multiple DSL lines), and setting up the arp and routing to make the 
packet actually go via the primary interface.

However, therein lies another problem - it means that the primary (real) 
interface (with the first subnet) could then not be shaped properly (I 
THINK), because shaping it would shape the overall traffic on that 
interface, and not only the traffic on the primary connection.

So, the solution might be to set up the real interface with a dummy IP 
address, and assigning all valid, real subnets to the dummy interfaces, 
and set up the routes for those subnets to go via the real interface, 
and set up arp to make sure things go via the real interface.

Has anybody got any thoughts on this?

If this would work, maybe it should be documented in the advanced 
routing howto, as I can see how there might be a lot of people out 
there who would find it useful.

Regards.

Gordan
_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/

Re: [LARTC] Shaping Device Aliases

[Martin A. Brown]

Gordan,

I've noticed that you are trying to use aliased IP addresses and traffic
control together, and you are a bit frustrated that tc doesn't handle
aliased interface names.

 : > > I understand that device aliases (e.g. eth2:3) are not shapeable.
 : > > Does anybody know if this functionality is planned in the future?
 : >
 : > None of the new(er) networking tools recognise device aliases,
 : > because on all recent linux releases, aliases don't exist.
 : > the ethX:X notation is a legacy notation used only by the ifconfig
 : > program. everything else just sees a ethX with more than one IP
 : > address.
 : >
 : > So you just run your shaping rules on the real interfaces, and
 : > restrict it's operation with IP address filtering.
 :
 : Yes, I am aware of that. However, that makes shaping multiple
 : independent "streams" going through one interface much more difficult.

I don't understand why this becomes much more difficult--it just becomes a
little more difficult, depending on the number of IP addresses you have
active on a given interface.  If you can handle multiple addresses on an
interface, then shaping traffic on these (known) addresses shouldn't be
much more difficult than managing each address.

 : The only other thing I can think of is setting up a dummy network
 : device and giving it the IP addresses on all the non-primary subnets
 : (e.g.  multiple DSL lines), and setting up the arp and routing to make
 : the packet actually go via the primary interface.

This sounds like a very confused idea.  I'm not sure it's worth the
hassle--as I hope I can convince you below.

[ more stuff snipped ]

 : Has anybody got any thoughts on this?

I have some thoughts, which I hope can help you understand why you will be
able to use the traffic control tools to accomplish your filtering.  For
posterity, I'll reiterate some of what has come before.

IP aliases don't exist.  This is a convention for ifconfig.  "ip addr
show" will display all IP addresses active on a given interface.

Traffic control is the last thing performed before turning the packet over
to the device driver and hardware.  Similarly, it is the first thing
called on receipt of a packet.  See diagrams KPTD [0] and ebtables packet
flow [1].

In this case, you can use any number of techniques to identify the packets
with tc tools based on their IP addresses--the convenience of the aliased
interface naming is simply an obstruction of the real path the packet
takes.

 : If this would work, maybe it should be documented in the advanced
 : routing howto, as I can see how there might be a lot of people out
 : there who would find it useful.

Let me suggest a possibility, if we assume a nested configuration.  Let's
say you have IP0 and IP1 active on interface eth3 and you want to make
sure that bandwidth is split 75/25 between these two and you want them to
share bandwidth.  Classic bandwidth-sharing situation....in the tcng
config below, you'd need to #define IP0 and IP1, but then you'd have a
simple configuration.  If you needed to further subdivide traffic within
each of the IP0 and IP1 classes, you'd have an easy way to do so.

    dev eth0 {
        egress {
            class ( <$ip0> )  if ip_src = IP0 ;
            class ( <$ip1> )  if ip_src = IP1 ;
            htb () {
                class ( rate 1544kbps, ceil 1544kbps ) {   /* T1 speed */
                    $ip0 = class ( rate 1024kbps, ceil 1544kbps ) ;
                    $ip1 = class ( rate  384kbps, ceil 1544kbps ) ;
                }
            }
        }
    }

Alternately, you may wish to simulate virtual circuits with each of the IP
addresses on a machine.  In this case, you could use separate root
classes attached to the HTB qdisc, or another class.  You can prevent the
two classes from competing with each other by setting the rate and ceil to
the same value.  Here's a very simple permutation of the above.

    dev eth0 {
        egress {
            class ( <$ip0> )  if ip_src = IP0 ;
            class ( <$ip1> )  if ip_src = IP1 ;
            htb () {
                class ( rate 1544kbps, ceil 1544kbps ) {   /* T1 speed */
                    $ip0 = class ( rate 1024kbps, ceil 1024kbps ) ;
                    $ip1 = class ( rate  384kbps, ceil  384kbps ) ;
                }
            }
        }
    }


Best of luck, Gordan!

-Martin

 [0] http://www.docum.org/stef.coene/qos/kptd/
 [1] http://ebtables.sourceforge.net/br_fw_ia/PacketFlow.png

-- 
Martin A. Brown --- SecurePipe, Inc. --- mabrown@securepipe.com

_______________________________________________
LARTC mailing list / LARTC@mailman.ds9a.nl
http://mailman.ds9a.nl/mailman/listinfo/lartc HOWTO: http://lartc.org/