upstream systemd discussion about MACAddressPolicy for bonds and bridges

[Dusty Mabe]

Just wanted to point interested people in the direction of an upstream
discussion about how (by default) the MAC address should get set for
bond and bridge devices.

https://lists.freedesktop.org/archives/systemd-devel/2022-May/047893.html

A few of us were originally going to propose a change to Fedora to change
the current behavior back, but it was suggested we take the discussion
upstream to hash out the merits there.

Please join the discussion if you have some perspective to add.

Dusty

[Tom Hughes]

On 10/05/2022 03:12, Dusty Mabe wrote:

>  Just wanted to point interested people in the direction of an
> upstream
>  discussion about how (by default) the MAC address should get set for
>  bond and bridge devices.
>  
>  https://lists.freedesktop.org/archives/systemd-devel/2022-May/047893.html
>  
>  A few of us were originally going to propose a change to Fedora to change
>  the current behavior back, but it was suggested we take the discussion
>  upstream to hash out the merits there. 
All I can say is, no, just leave it alone.

Having fixed all my machines two years ago when it stopped generating
persistent addresses I have just spent this weekend doing it again now
that F36 has gone back to them.

I don't care what address my bridges have, so long as it is fixed so
that DHCP can allocate addresses against it, but I do prefer not to
have to fix all my DHCP and DNS every time the policy flip flops and
upgrades break my networks!

Tom

-- 
Tom Hughes (tom(a)compton.nu)
http://compton.nu/

[Dusty Mabe]

On 5/10/22 02:05, Tom Hughes via devel wrote:
>  On 10/05/2022 03:12, Dusty Mabe wrote:
>  
> > Just wanted to point interested people in the direction of an upstream
> > discussion about how (by default) the MAC address should get set for
> > bond and bridge devices.
> >
> > https://lists.freedesktop.org/archives/systemd-devel/2022-May/047893.html
> >
> > A few of us were originally going to propose a change to Fedora to change
> > the current behavior back, but it was suggested we take the discussion
> > upstream to hash out the merits there.
>  
>  All I can say is, no, just leave it alone.
>  
>  Having fixed all my machines two years ago when it stopped generating
>  persistent addresses I have just spent this weekend doing it again now
>  that F36 has gone back to them. 
I'm not aware of any change in behavior in F36, but maybe I missed something.

>  
>  I don't care what address my bridges have, so long as it is fixed so
>  that DHCP can allocate addresses against it, but I do prefer not to
>  have to fix all my DHCP and DNS every time the policy flip flops and
>  upgrades break my networks!
>   
With the current policy you'll get a new MAC every time you re-install
a machine. Is that what you want? 

The upstream proposal is to make it based on the actual MAC of the NIC(s)
again.

Dusty

[Tom Hughes]

On 10/05/2022 14:57, Dusty Mabe wrote:
>  
>  
>  On 5/10/22 02:05, Tom Hughes via devel wrote:
> > On 10/05/2022 03:12, Dusty Mabe wrote:
> >
> >> Just wanted to point interested people in the direction of an upstream
> >> discussion about how (by default) the MAC address should get set for
> >> bond and bridge devices.
> >>
> >> https://lists.freedesktop.org/archives/systemd-devel/2022-May/047893.html
> >>
> >> A few of us were originally going to propose a change to Fedora to change
> >> the current behavior back, but it was suggested we take the discussion
> >> upstream to hash out the merits there.
> >
> > All I can say is, no, just leave it alone.
> >
> > Having fixed all my machines two years ago when it stopped generating
> > persistent addresses I have just spent this weekend doing it again now
> > that F36 has gone back to them.
>  
>  I'm not aware of any change in behavior in F36, but maybe I missed something. 
F36 has gone back to using a persistent MAC calculated from
the machine ID and bridge name.

I'm not sure what F35 was doing but believe me when I say that
all my bridges changed MAC on upgrade and they've now gone back
to the address they had until late 2019 or early 2020.

> > I don't care what address my bridges have, so long as it is
> fixed so
> > that DHCP can allocate addresses against it, but I do prefer not to
> > have to fix all my DHCP and DNS every time the policy flip flops and
> > upgrades break my networks!
>  
>  With the current policy you'll get a new MAC every time you re-install
>  a machine. Is that what you want? 
It doesn't bother me too much as I expect to be reconfiguring
things then.

>  The upstream proposal is to make it based on the actual MAC of the
> NIC(s)
>  again. 
The problem is which NIC exactly? As I understand it's whatever
interface gets added first so may be racy.

 From that point of view a persistent address seems better.

Tom

-- 
Tom Hughes (tom(a)compton.nu)
http://compton.nu/