* [Bridge] Why should static MAC address match one of the port MAC addresses.
@ 2010-10-12 13:40 Michel Lammertink
2010-10-12 16:44 ` Stephen Hemminger
0 siblings, 1 reply; 4+ messages in thread
From: Michel Lammertink @ 2010-10-12 13:40 UTC (permalink / raw
To: bridge
Hi all,
I've read many messages on this mailing list with the question about
setting a static MAC address on the bridge interface, but two questions
remain:
1. Why should the MAC address of the bridge match the address of one of
its interfaces? Setting the MAC address to a different value does not
generate an error, but the bridge is not working properly (Local data
does not arrive).
2. Why does the bridge by default choose the "lowest" MAC address,
instead of the MAC address of the first port added, as is proposed by
the standard [1]?
[1] IEEE802.1D, Par. 7.12.5.
Quote: "The Bridge Address may be the individual MAC Address of a
Bridge Port, in which case, use of the address of the lowest numbered
Bridge Port (Port 1) is recommended."
Thanks in advance,
Michel.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Bridge] Why should static MAC address match one of the port MAC addresses.
2010-10-12 13:40 Michel Lammertink
@ 2010-10-12 16:44 ` Stephen Hemminger
0 siblings, 0 replies; 4+ messages in thread
From: Stephen Hemminger @ 2010-10-12 16:44 UTC (permalink / raw
To: Michel Lammertink; +Cc: bridge
On Tue, 12 Oct 2010 15:40:25 +0200
Michel Lammertink <mlammertink@ti-wmc.nl> wrote:
> Hi all,
>
> I've read many messages on this mailing list with the question about
> setting a static MAC address on the bridge interface, but two questions
> remain:
>
> 1. Why should the MAC address of the bridge match the address of one of
> its interfaces? Setting the MAC address to a different value does not
> generate an error, but the bridge is not working properly (Local data
> does not arrive).
No longer a requirement. It was just a good way to ensure a good
address that was unique, and not being used by other systems.
> 2. Why does the bridge by default choose the "lowest" MAC address,
> instead of the MAC address of the first port added, as is proposed by
> the standard [1]?
It was a convenience in original design to choose a consistent value.
Since ports can be added in any order, using the lowest seemed like
a good idea for the original author. This has been maintained for
backwards compatibility.
> [1] IEEE802.1D, Par. 7.12.5.
> Quote: "The Bridge Address may be the individual MAC Address of a
> Bridge Port, in which case, use of the address of the lowest numbered
> Bridge Port (Port 1) is recommended."
>
> Thanks in advance,
>
> Michel.
> _______________________________________________
> Bridge mailing list
> Bridge@lists.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/bridge
--
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Bridge] Why should static MAC address match one of the port MAC addresses.
@ 2010-12-19 22:16 Rolf Fokkens
2010-12-19 22:19 ` Rolf Fokkens
0 siblings, 1 reply; 4+ messages in thread
From: Rolf Fokkens @ 2010-12-19 22:16 UTC (permalink / raw
To: bridge
[-- Attachment #1: Type: text/plain, Size: 2669 bytes --]
Hi all,
I'm having the problem Michiel describes as well. I have a bridge br2
containing 1 (but potentially more) tap interface for kvm. Windows 7 VM
doesn't like the bridge mac address to change, so I try to make it fixed.
ifconfig br2 hw ether 02:00:00:00:01:02
Interface br2 becomes instantly unreachable from the VM (via the tap
interface).
So, Michiel's claim still seems to be true: the bridge mac address
should apparently be one of the bridge interfaces.
I don't see the logic, this seems like a bug to me.
Cheers,
Rolf
------------------------------------------------------------------------
* /To/: Michel Lammertink <mlammertink@xxxxxxxxx
<mailto:mlammertink@DOMAIN.HIDDEN>>
* /Subject/: Re: Why should static MAC address match one of the port
MAC addresses.
* /From/: Stephen Hemminger <shemminger@xxxxxxxxxxxxxxxxxxxx
<mailto:shemminger@DOMAIN.HIDDEN>>
* /Date/: Tue, 12 Oct 2010 09:44:08 -0700
* /Cc/: bridge@xxxxxxxxxxxxxxxxxxxxxxxxxx <mailto:bridge@DOMAIN.HIDDEN>
* /In-reply-to/: <4CB46549.2070901@xxxxxxxxx
<mailto:4CB46549.2070901@DOMAIN.HIDDEN>>
* /Organization/: Linux Foundation
* /References/: <4CB46549.2070901@xxxxxxxxx
<mailto:4CB46549.2070901@DOMAIN.HIDDEN>>
------------------------------------------------------------------------
On Tue, 12 Oct 2010 15:40:25 +0200 Michel Lammertink<mlammertink@xxxxxxxxx> wrote:
>/ Hi all,/
>/ /
>/ I've read many messages on this mailing list with the question about/
>/ setting a static MAC address on the bridge interface, but two questions/
>/ remain:/
>/ /
>/ 1. Why should the MAC address of the bridge match the address of one of/
>/ its interfaces? Setting the MAC address to a different value does not/
>/ generate an error, but the bridge is not working properly (Local data/
>/ does not arrive)./
No longer a requirement. It was just a good way to ensure a good
address that was unique, and not being used by other systems.
>/ 2. Why does the bridge by default choose the "lowest" MAC address,/
>/ instead of the MAC address of the first port added, as is proposed by/
>/ the standard [1]?/
It was a convenience in original design to choose a consistent value.
Since ports can be added in any order, using the lowest seemed like
a good idea for the original author. This has been maintained for
backwards compatibility.
>/ [1] IEEE802.1D, Par. 7.12.5./
>/ Quote: "The Bridge Address may be the individual MAC Address of a/
>/ Bridge Port, in which case, use of the address of the lowest numbered/
>/ Bridge Port (Port 1) is recommended."/
>/ /
>/ Thanks in advance,/
>/ /
>/ Michel./
[-- Attachment #2: Type: text/html, Size: 3336 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Bridge] Why should static MAC address match one of the port MAC addresses.
2010-12-19 22:16 [Bridge] Why should static MAC address match one of the port MAC addresses Rolf Fokkens
@ 2010-12-19 22:19 ` Rolf Fokkens
0 siblings, 0 replies; 4+ messages in thread
From: Rolf Fokkens @ 2010-12-19 22:19 UTC (permalink / raw
To: bridge
[-- Attachment #1: Type: text/plain, Size: 2922 bytes --]
Forgot some specifics:
kernel is Fedora kernel-2.6.35.9-64.fc14.x86_64.
On 12/19/2010 11:16 PM, Rolf Fokkens wrote:
> Hi all,
>
> I'm having the problem Michiel describes as well. I have a bridge br2
> containing 1 (but potentially more) tap interface for kvm. Windows 7
> VM doesn't like the bridge mac address to change, so I try to make it
> fixed.
>
> ifconfig br2 hw ether 02:00:00:00:01:02
>
> Interface br2 becomes instantly unreachable from the VM (via the tap
> interface).
>
> So, Michiel's claim still seems to be true: the bridge mac address
> should apparently be one of the bridge interfaces.
>
> I don't see the logic, this seems like a bug to me.
>
> Cheers,
>
> Rolf
>
> ------------------------------------------------------------------------
>
> * /To/: Michel Lammertink <mlammertink@xxxxxxxxx
> <mailto:mlammertink@DOMAIN.HIDDEN>>
> * /Subject/: Re: Why should static MAC address match one of the
> port MAC addresses.
> * /From/: Stephen Hemminger <shemminger@xxxxxxxxxxxxxxxxxxxx
> <mailto:shemminger@DOMAIN.HIDDEN>>
> * /Date/: Tue, 12 Oct 2010 09:44:08 -0700
> * /Cc/: bridge@xxxxxxxxxxxxxxxxxxxxxxxxxx
> <mailto:bridge@DOMAIN.HIDDEN>
> * /In-reply-to/: <4CB46549.2070901@xxxxxxxxx
> <mailto:4CB46549.2070901@DOMAIN.HIDDEN>>
> * /Organization/: Linux Foundation
> * /References/: <4CB46549.2070901@xxxxxxxxx
> <mailto:4CB46549.2070901@DOMAIN.HIDDEN>>
>
> ------------------------------------------------------------------------
> On Tue, 12 Oct 2010 15:40:25 +0200 Michel Lammertink<mlammertink@xxxxxxxxx> wrote:
>
> >/ Hi all,/
> >/ /
> >/ I've read many messages on this mailing list with the question about/
> >/ setting a static MAC address on the bridge interface, but two questions/
> >/ remain:/
> >/ /
> >/ 1. Why should the MAC address of the bridge match the address of one of/
> >/ its interfaces? Setting the MAC address to a different value does not/
> >/ generate an error, but the bridge is not working properly (Local data/
> >/ does not arrive)./
>
> No longer a requirement. It was just a good way to ensure a good
> address that was unique, and not being used by other systems.
>
> >/ 2. Why does the bridge by default choose the "lowest" MAC address,/
> >/ instead of the MAC address of the first port added, as is proposed by/
> >/ the standard [1]?/
>
> It was a convenience in original design to choose a consistent value.
> Since ports can be added in any order, using the lowest seemed like
> a good idea for the original author. This has been maintained for
> backwards compatibility.
>
> >/ [1] IEEE802.1D, Par. 7.12.5./
> >/ Quote: "The Bridge Address may be the individual MAC Address of a/
> >/ Bridge Port, in which case, use of the address of the lowest numbered/
> >/ Bridge Port (Port 1) is recommended."/
> >/ /
> >/ Thanks in advance,/
> >/ /
> >/ Michel./
[-- Attachment #2: Type: text/html, Size: 3891 bytes --]
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2010-12-19 22:19 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-12-19 22:16 [Bridge] Why should static MAC address match one of the port MAC addresses Rolf Fokkens
2010-12-19 22:19 ` Rolf Fokkens
-- strict thread matches above, loose matches on Subject: below --
2010-10-12 13:40 Michel Lammertink
2010-10-12 16:44 ` Stephen Hemminger
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.