Re: [linux-vrf-core] One interface with multiple vrfs

[James R. L. <jl...@mi...>]

Hello Nick,

You are correct in pointing out that VLAN interfaces can be added a VRF.
AFAICT any interface that shows up in 'ip link show' can be assigned to
a VRF.  IP alias interfaces cannot be assigned to a VRF because they are not
'real' kernel interfaces, just IP 'interfaces', and do not show up
in 'ip link show'.

Cheers
--=20
James R. Leu
jl...@mi...

On Wed, Sep 20, 2006 at 10:16:02AM -0400, Nick Eggleston wrote:
> Hi James,
>=20
> What about the following:
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> eth0 is connected to trunk port on a switch.
> using vconfig on linux, we create vlan interfaces, like:
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> vconfig add eth0 5
> vconfig add eth0 10
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> That should create two new interfaces in the system:
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> eth0.5
> eth0.10
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> now, we would want to put each of those vlan interfaces into a separate
> vrf. for example, each vlan could carry traffic for a different
> customer, both of whom share the same ip space.
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> That should work today, right?  I am thinking that is what Matthias had
> in mind (of course, I cold be wrong)
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> I agree with you on the problem of what to do, if the same interface
> were in two more more vrfs simultaneously.  You would then have to make
> routing decisions based on some complex series of rules.  in that case
> (why would one ever want to do it?) netfilter would probably be the
> place to make those decisions. =20
>=20
> All the best,
>=20
> Nick
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> =20
>=20
> > -----Original Message-----
> > From: lin...@li...
> [mailto:linux-vrf-core-
> > bo...@li...] On Behalf Of James R. Leu
> > Sent: Wednesday, September 20, 2006 9:00 AM
> > To: mat...@ne...
> > Cc: lin...@li...
> > Subject: Re: [linux-vrf-core] One interface with multiple vrfs
> >=20
> > Hello,
> >=20
> > This is not a case I had thought about when implementing, so help me
> > understand the motivation:
> >=20
> > Why would you want an interface to be in multiple VRFs?
> > How would you want incoming packets on said interface to be routed?
> >=20
> > Currently, there is a many-to-one relationship (multiple interfaces
> can
> > be added to a VRF, but only one VRF per interface).  This is so that
> > IP packets coming in an interface only need to be looked up in one
> routing
> > table. If there were multiple VRFs associated with an interface what
> > routing table would incoming packets be routed according to?
> >=20
> > If you have a userland application that needs to transmit IP packets
> > 'in' different VRFs then that application should either use the
> 'chvrf'
> > utility to set the VRF associated with a process, or use the VRF
> socket
> > option to set the VRF associated with a socket.
> >=20
> > On Wed, Sep 20, 2006 at 01:49:14PM +0200,
> mat...@ne...
> > wrote:
> > > First I tried to add multiple vrf to one interface. But it doesn't
> run.
> > > Then I tried to add multiple vrf to a vlan, but I get the message:
> no
> > such
> > > device.
> > >
> > > Is it possible to run one interface in multiple vrfs?
> > >
> > >
> > > Regards,
> > >
> > > Matthias Flittner
> >=20
> > >
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> >=20
> >=20
> > --
> > James R. Leu
> > jl...@mi...