[ovs-dev] [patch net-next RFC 04/12] rtnl: expose physical switch id for particular device

Jiri Pirko jiri at resnulli.us
Tue Aug 26 08:32:23 UTC 2014

Fri, Aug 22, 2014 at 09:08:39PM CEST, john.fastabend at gmail.com wrote:
>On 08/21/2014 09:18 AM, Jiri Pirko wrote:
>>The netdevice represents a port in a switch, it will expose
>>IFLA_PHYS_SWITCH_ID value via rtnl. Two netdevices with the same value
>>belong to one physical switch.
>>Signed-off-by: Jiri Pirko <jiri at resnulli.us>
>What is the relation between phys_port_id and phys_switch_id?
>phys_port_id was intended to identify a set of ports that belong
>to a single uplink port,
>	eth0     eth1    eth2   eth3      (host facing)
>          |       |       |      |
>          |       |       |      |
>      +---+-------+-------+------+---+
>      |      embedded switch         |
>      +------------------------------+
>                     |
>                    MAC                   (network)
>In the NIC case there is a simply switch with a port to the
>network which we currently don't represent with a netdev. Any
>netdev where the phys_switch_id's are behind the same embedded

I think that MAC in your picture should be represented as netdev (switch
port). Also, the other ports connected to eth0-3 should be represented
as netdevs. All of these + the MAC should have the same switch id.

>In the switch id case we are indicating the port is attached to
>the same embedded switch as well.
>         eth0 eth1 eth2 eth3
>          |    |    |    |
>     +----+----+----+----+----+
>     |         switch         |
>     +----+----+----+----+----+
>but they do not share an uplink port? So in this case each ethx
>has a unique phys_port_id but the same phys_switch_id?


>In the first case both phys_port_id and phys_switch_id should
>be equal for all interfaces correct?

See above. In case of embedded switch on nic I believe that eth0-eth3
shoud have the same port_id and no switch_id as they are not ports of
switch (the counterparts in switch (marked as "+" on your picture are
the switch ports)

>Is that clear/useful at all? We need to document this somewhere
>if/when the patches are submitted otherwise I doubt we will get it
>consistently right across drivers. There could for example be
>somewhat strange devices with virtual functions hanging off of the

I will extend the documentation to my "net: introduce generic switch
devices support" patch.

>John Fastabend         Intel Corporation

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