Subject: Re: [patch net-next RFC 0/4] introduce infrastructure for support of switch chip datapath

From: "John W. Linville" <[email-masked]>
Date: Thu, 27 Mar 2014 09:46:26 -0400

On Wed, Mar 26, 2014 at 11:09:43AM -0700, Florian Fainelli wrote:
> 2014-03-26 10:57 GMT-07:00 Roopa Prabhu <[email-masked]>:
> > On 3/26/14, 10:29 AM, Florian Fainelli wrote:
> >>
> >> 2014-03-26 9:59 GMT-07:00 Jiri Pirko <[email-masked]>:
> >>>
> >>> Wed, Mar 26, 2014 at 05:54:17PM CET, [email-masked] wrote:
> >>>>
> >>>> On 3/26/14, 3:54 AM, Jamal Hadi Salim wrote:
> >>>>>
> >>>>> On 03/26/14 01:37, Roopa Prabhu wrote:
> >>>>>>
> >>>>>> On 3/25/14, 1:11 PM, Florian Fainelli wrote:
> >>>>>>>
> >>>>>>> 2014-03-25 12:35 GMT-07:00 Neil Horman <[email-masked]>:
> >>>>>>
> >>>>>> Sorry about getting on this thread late and possibly in the middle.
> >>>>>> Agree on the idea of keeping the ports linked to the master switch dev
> >>>>>> (or the 'conduit' to the switch chip) via private list instead of the
> >>>>>> master-slave relationship proposed earlier.
> >>>>>> By private i mean the netdev->priv linkage to the master switch dev
> >>>>>> and
> >>>>>> not really keeping the ports from being exposed to the user.
> >>>>>>
> >>>>>> We think its better to keep the switch ports exposed as any other
> >>>>>> netdev
> >>>>>> on linux.
> >>>>>>   This approach will make the switch ports look exactly like a nic
> >>>>>> port
> >>>>>> and all tools will continue to work seamlessly. The switch port
> >>>>>> operations could internally be forwarded to the switch netdev (sw1 in
> >>>>>> the above case).
> >>>>>>
> >>>>>> example:
> >>>>>> $ip link set dev sw1p0 up
> >>>>>> $ethtool -S sw1p0
> >>>>>>
> >>>>> I like the approach. I know the above is a simple version, but i am
> >>>>> assuming you also mean i can do things like
> >>>>> ip route add ...
> >>>>> bridge fdb add ... (and if you like your brctl go ahead)
> >>>>> bonding ...
> >>>>>
> >>>> yes, exactly.  We support this model on our boxes today.
> >>>> User can bond switch ports on our box in the exact same way as he/she
> >>>> would bond two nic ports.
> >>>> Our 'conduit to switch chip' reflects the corresponding lag
> >>>> configuration in the switch chip.
> >>>> Same goes for bridging, routing, acls.
> >>>
> >>>
> >>> So you implement bonding netlink api? Or you hook into bonding driver
> >>> itselt? Can you show us the code?
> >>
> >> Before we start talking about bonding, maybe we should make sure that
> >> we cover some basic hardware switches uses which are to make some
> >> ports belong to certain VLANs, tagged or untagged?
> >>
> >> It seems to me like this would become something like this, assuming P0
> >> and P1 are two switch ports and 'eth0' is the CPU port, where P0 and
> >> P1 belong to VLAN1 and CPU belongs to VLAN2:
> >>
> >> ip link set dev sw1p0 up
> >> ip link set dev sw1p1 up
> >> ip link set dev eth0 up
> >>
> >> ip link add link eth0 name eth0.2 type vlan id 2
> >>
> >> ip link add link sw1p0 name sw1p0.1 type vlan id 1
> >> ip link add link sw1p1 name sw1p1.1 type vlan id 1
> >>
> >> ip link add sw1.1 type bridge
> >> ip link set sw1p0.1 master sw1.1
> >> ip link set sw1p1.1 master sw1.1
> >>
> >> Does that fit the model correctly?
> >
> > Not entirely, but close.
> > In our current model, there is no netdev for cpu port (or master switch
> > netdev):
> 
> You mean there is no netdev for the switch-side CPU-port facing the
> CPU Ethernet MAC, right? There is still a netdev for the CPU Ethernet
> MAC to receive packets destined to it presumably.
> 
> I do not think it hurts nor changes anything to introduce a CPU-port
> netdev, this just gives greater flexibility and this should allow for
> more complex setups where multiple CPU-ports exist (there are some
> real devices using this...).

But how is this useful?  It just seems redundant to me.  Also, how
should we communicate to the user that a given interface on the switch
is hardwired to a given NIC on the CPU?
 
> >
> >
> > ip link set dev sw1p0 up
> > ip link set dev sw1p1 up
> >
> > ip link add link sw1p0 name sw1p0.1 type vlan id 1
> > ip link add link sw1p1 name sw1p1.1 type vlan id 1
> >
> > ip link add brvlan1 type bridge
> > ip link set swp1p0.1 master brvlan1
> > ip link set swp1p1.1 master brvlan1
> >
> > switch driver programs the brvlan1 vlan in the switch asic.
> >
> > bonding works in the same way.
> >
> > Thanks,
> > Roopa
> >
> >
> >
> >
> >
> 
> 
> 
> -- 
> Florian
> --
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-- 
John W. Linville		Someday the world will need a hero, and you
[email-masked]			might be all we have.  Be ready.