On 2019-02-27 11:13, Florian Fainelli wrote:
On 2/26/2019 6:04 PM, xiaofeis@xxxxxxxxxxxxxx wrote:
On 2019-02-26 15:45, xiaofeis@xxxxxxxxxxxxxx wrote:
On 2019-02-26 01:27, Florian Fainelli wrote:
On 2/25/19 5:28 AM, xiaofeis@xxxxxxxxxxxxxx wrote:
Hi Florian
We have two slave DSA interfaces, wan0 and lan0, one is for wan
port,
and the other is for lan port. Customer has it's mac address pool,
they
want
to assign the mac address from the pool on wan0, lan0, and other
interfaces like
wifi, bt. Coreboot/uboot will populate it to the DTS node, so the
driver
can
get it from it's node. For DSA slave interface, it already has it's
own
DTS node, it's
easy to just add one porperty "local-mac-address" there for the
usage in
DSA driver.
If not use DSA framework, normally we will use eth0.x and eth0.y
for
wan
and lan.
On this case, customer usually also assign the MAC address on these
logical interface
from it's pool.
OK, but this is not necessary per my previous explanation: the CPU
<=>
WAN pipe is a separate broadcast domain (otherwise it is a security
hole
since you exposing LAN machines to the outside world), and so there
is
no need for a separate MAC address. It might be convenient to have
one,
especially for the provider, if they run a management software
(e.g.:
TR69), but it is not required per-se.
Let me ask a secondary question here, how many Ethernet MACs connect
to
the switch in this configuration? Is there one that is supposed to
be
assigned all LAN traffic and one that is supposed to be assigned all
WAN
traffic? If so, then what you are doing makes even less
Only one MAC connected to switch cpu port, both lan0 and wan0 are on
the top of
same interface(eth0).
Customer doesn't care about the MAC controller's MAC address, just
leave
it as the driver
randomly generated. They just want to assign the MAC address on wan
and
lan DSA logical
interface.
Many customer doesn't use DSA, for example, they use eth0.1/eth0.2 for
lan/wan with one MAC controller.
They configure switch wan port in vlan2 group, and lan port in vlan1
group, they usually assign mac address
on the logical interface(eth0.1ð0.2), i think this is similar with
DSA slave interfaces.
Yes it is a similar use case, and in both cases there is no really a
functional need for a separate MAC address for lan/eth0.1 or wan/eth0.2
since the switch should be configured to perform IVL (Individual VLAN
Learning) and would determine the egress port just fine based on the
MAC
DA. Because it is an established practice does not mean we should not
challenge it :).
My issue with your change is that because DSA is meant to be a flexible
framework we do not know the type/nature of DSA master network device
that is going to be used. That DSA master network device may or may not
have it own MAC DA filtering capability. Having to filter its own MAC
address is fine and a well established behavior, having to filter for
more than one unicast address starts to be questionable and eats up
filter space that could be better used for filtering MC addresses
instead. Another possible concern is a station trying to spoof the MAC
address, some switches may support protecting only one UC/management
MAC
address, so having more than one could create security attack surfaces.
To give you an example, I work with 3 generations of DSA master network
controllers (bcmgenet and bcmsysport drivers).
- GENET supports 17 perfect filters, but we must include its own MAC
address, the broadcast address and that leaves only 15 filters for MC
- SYSTEMPORT is always attached to a switch but supports filtering the
MAC DA based on its own MAC and then it is in promiscuous mode
So with your scheme, we would leave only 13 filters for MC on GENET and
we would putting the interface in promiscuous mode for SYSTEMPORT.
Until we have a better switch-side filtering framework (and this is
being worked on right now), I would prefer that we defer accepting
those
type of features. Andrew and Vivien might feel differently about that
though.
This patch is just add one more option, if there is valid mac address
populated
in the DTS, then use it or else still inherti from master. I don't think
it will
break the DSA flexible framework. I think this change make DSA more
flexible on
MAC address setting.
Many cusomter use some of our QCA chips, some direclty use DSA, some use
internal similar
mechanism(one netdevice for each switch port with swtichdev), we didn't
see any limiation
when they populiate the mac address for each port in DTS with only one
HW mac controller.
So my opinion is this patch is want to add a option which is already
used in many
products, this change does not break anything, developer/customer can
chose use or not.
