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Old 07-21-2008, 08:06 PM
Warren Togami
 
Default brctl setfd virbr0 0.1 by default?

https://bugzilla.redhat.com/show_bug.cgi?id=435757
Sometime after F8, something changed where stuff attached to a bridge
fails to connect until 15 seconds later. A manual workaround of brctl
setfd BRIDGENAME 0.1 makes stuff work immediately.


Are there any reasons why don't we do this by default for virbr0 in libvirt?

Use cases:
- Attach a different tun/tap device to the virbr0 bridge to talk to your
virtual machine.
- Attach ethX real device to your vribr0 bridge to talk to your virtual
machine without NAT (like if you are doing DHCP.)


Warren Togami
wtogami@redhat.com

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Old 07-21-2008, 09:40 PM
Chuck Anderson
 
Default brctl setfd virbr0 0.1 by default?

> https://bugzilla.redhat.com/show_bug.cgi?id=435757
> Sometime after F8, something changed where stuff attached to a bridge
> fails to connect until 15 seconds later. A manual workaround of brctl
> setfd BRIDGENAME 0.1 makes stuff work immediately.
>
> Are there any reasons why don't we do this by default for virbr0 in libvirt?
>
> Use cases:
> - Attach a different tun/tap device to the virbr0 bridge to talk to your
> virtual machine.
> - Attach ethX real device to your vribr0 bridge to talk to your virtual
> machine without NAT (like if you are doing DHCP.)

I would assume that brctl or the kernel became fully 802.1d Spanning
Tree Protocol compliant. Compliant bridges MUST delay entering the
forwarding state at link up or initialization, transitioning between
LISTENING and LEARNING states first. This is required by the
standard.

That being said, most really switches support a per-port "fast start"
mode sometimes called "portfast" or "edge" where the port is
designated to be connected directly to an end system rather than
another bridge/switch, which causes the forwarding delay to be set to
0. This is not strictly compliant to the standard, but is often used
because of the issue where DHCP clients will time out after 15
seconds.

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Old 07-22-2008, 09:58 AM
"Daniel P. Berrange"
 
Default brctl setfd virbr0 0.1 by default?

On Mon, Jul 21, 2008 at 04:06:50PM -0400, Warren Togami wrote:
> https://bugzilla.redhat.com/show_bug.cgi?id=435757
> Sometime after F8, something changed where stuff attached to a bridge
> fails to connect until 15 seconds later. A manual workaround of brctl
> setfd BRIDGENAME 0.1 makes stuff work immediately.
>
> Are there any reasons why don't we do this by default for virbr0 in libvirt?

Because no one has ever suggested it before...

Arguably we should just turn off STP on the virbr0 device. Since it is
not connected directly to the public LAN[1] there is no risk of network
loops and thus spanning tree protocol is pointless for virbr0. I wonder
if somewhere along the lines post F8 GA, STP accidentally got toggled
from offf by default to on by default on virbr0. Please file a BZ about
this problem.

Daniel

[1] The only connectivity is outbound, masqueraded / NAT traffic.
--
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Old 07-22-2008, 02:22 PM
Warren Togami
 
Default brctl setfd virbr0 0.1 by default?

Daniel P. Berrange wrote:

On Mon, Jul 21, 2008 at 04:06:50PM -0400, Warren Togami wrote:

https://bugzilla.redhat.com/show_bug.cgi?id=435757
Sometime after F8, something changed where stuff attached to a bridge
fails to connect until 15 seconds later. A manual workaround of brctl
setfd BRIDGENAME 0.1 makes stuff work immediately.


Are there any reasons why don't we do this by default for virbr0 in libvirt?


Because no one has ever suggested it before...

Arguably we should just turn off STP on the virbr0 device. Since it is
not connected directly to the public LAN[1] there is no risk of network
loops and thus spanning tree protocol is pointless for virbr0. I wonder
if somewhere along the lines post F8 GA, STP accidentally got toggled
from offf by default to on by default on virbr0. Please file a BZ about

this problem.

Daniel

[1] The only connectivity is outbound, masqueraded / NAT traffic.


Disabling STP on virbr0 alone is not enough. I just tested it now. STP
enabled or disabled, the default forward delay of 15 seconds makes it
fail for 15 seconds, long enough for most DHCP clients to give up.


Given this, what should we do? Both disable STP and also reduce the delay?

Warren Togami
wtogami@redhat.com

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Old 07-22-2008, 02:51 PM
"Daniel P. Berrange"
 
Default brctl setfd virbr0 0.1 by default?

On Tue, Jul 22, 2008 at 10:22:12AM -0400, Warren Togami wrote:
> Daniel P. Berrange wrote:
> >On Mon, Jul 21, 2008 at 04:06:50PM -0400, Warren Togami wrote:
> >>https://bugzilla.redhat.com/show_bug.cgi?id=435757
> >>Sometime after F8, something changed where stuff attached to a bridge
> >>fails to connect until 15 seconds later. A manual workaround of brctl
> >>setfd BRIDGENAME 0.1 makes stuff work immediately.
> >>
> >>Are there any reasons why don't we do this by default for virbr0 in
> >>libvirt?
> >
> >Because no one has ever suggested it before...
> >
> >Arguably we should just turn off STP on the virbr0 device. Since it is
> >not connected directly to the public LAN[1] there is no risk of network
> >loops and thus spanning tree protocol is pointless for virbr0. I wonder
> >if somewhere along the lines post F8 GA, STP accidentally got toggled
> >from offf by default to on by default on virbr0. Please file a BZ about
> >this problem.
> >
> >Daniel
> >
> >[1] The only connectivity is outbound, masqueraded / NAT traffic.
>
> Disabling STP on virbr0 alone is not enough. I just tested it now. STP
> enabled or disabled, the default forward delay of 15 seconds makes it
> fail for 15 seconds, long enough for most DHCP clients to give up.
>
> Given this, what should we do? Both disable STP and also reduce the delay?

I think I understand what's going on here.

- The libvirt 'default' network XML config (aka that for virbr0) does
not specify any forward delay or STP setting, so it defaults to
delay=0, and STP=on

- The libvirt in F8 GA had a bug, where it called 'setfd' instead
'stp' when invoking brctl.

- Thus, the default config would result in a bridge with STP off
and a delay of 1 second.

- A libvirt update fixed the bug in the way we call brctl. Fixing
the bug means we now by default create a bridge with STP on
and the default kernel delay setting of 15 seconds.

- There is a further bug in that if you specify delay=0 in the XML
it'll never call 'brctl setfd 0', so you'll be stuck with the 15
second default still.

So yes, we need to fix things such that it has STP=on and a tiny (or even
zer) forward forward delay again, as per F8 GA behaviour. Can you file
a BZ about this problem against libvirt. It impacts F9 and rawhide too

Daniel
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Old 07-22-2008, 02:56 PM
Don Dutile
 
Default brctl setfd virbr0 0.1 by default?

Warren Togami wrote:
> Daniel P. Berrange wrote:
>> On Mon, Jul 21, 2008 at 04:06:50PM -0400, Warren Togami wrote:
>>> https://bugzilla.redhat.com/show_bug.cgi?id=435757
>>> Sometime after F8, something changed where stuff attached to a bridge
>>> fails to connect until 15 seconds later. A manual workaround of
>>> brctl setfd BRIDGENAME 0.1 makes stuff work immediately.
>>>
>>> Are there any reasons why don't we do this by default for virbr0 in
>>> libvirt?
>>
>> Because no one has ever suggested it before...
>>
>> Arguably we should just turn off STP on the virbr0 device. Since it is
>> not connected directly to the public LAN[1] there is no risk of network
>> loops and thus spanning tree protocol is pointless for virbr0. I wonder
>> if somewhere along the lines post F8 GA, STP accidentally got toggled
>> from offf by default to on by default on virbr0. Please file a BZ about
>> this problem.
>>
>> Daniel
>>
>> [1] The only connectivity is outbound, masqueraded / NAT traffic.
>
> Disabling STP on virbr0 alone is not enough. I just tested it now. STP
> enabled or disabled, the default forward delay of 15 seconds makes it
> fail for 15 seconds, long enough for most DHCP clients to give up.
>
> Given this, what should we do? Both disable STP and also reduce the delay?
>

Try reducing the delay to 0. I believe this is the same/similar issue that
Herbert Xu is dealing with when xen guests are migrated, and the guest doesn't
see the network for some number of seconds.
I'm trying to find the BZ & thread that had this info in it, but searching
through xen-maint bz's is not turning up what I'm looking for.
BZ 441716 proposes another solution for rhel5; not sure if fedora needs it as well.

- Don

> Warren Togami
> wtogami@redhat.com
>

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Old 07-22-2008, 07:38 PM
David Woodhouse
 
Default brctl setfd virbr0 0.1 by default?

On Tue, 2008-07-22 at 10:58 +0100, Daniel P. Berrange wrote:
> On Mon, Jul 21, 2008 at 04:06:50PM -0400, Warren Togami wrote:
> > https://bugzilla.redhat.com/show_bug.cgi?id=435757
> > Sometime after F8, something changed where stuff attached to a bridge
> > fails to connect until 15 seconds later. A manual workaround of brctl
> > setfd BRIDGENAME 0.1 makes stuff work immediately.
> >
> > Are there any reasons why don't we do this by default for virbr0 in libvirt?
>
> Because no one has ever suggested it before...
>
> Arguably we should just turn off STP on the virbr0 device. Since it is
> not connected directly to the public LAN[1] there is no risk of network
> loops and thus spanning tree protocol is pointless for virbr0.

Is there no chance of bridging directly to the outside world by adding a
real Ethernet device to the bridge?

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Old 07-23-2008, 08:27 AM
"Daniel P. Berrange"
 
Default brctl setfd virbr0 0.1 by default?

On Tue, Jul 22, 2008 at 03:38:39PM -0400, David Woodhouse wrote:
> On Tue, 2008-07-22 at 10:58 +0100, Daniel P. Berrange wrote:
> > On Mon, Jul 21, 2008 at 04:06:50PM -0400, Warren Togami wrote:
> > > https://bugzilla.redhat.com/show_bug.cgi?id=435757
> > > Sometime after F8, something changed where stuff attached to a bridge
> > > fails to connect until 15 seconds later. A manual workaround of brctl
> > > setfd BRIDGENAME 0.1 makes stuff work immediately.
> > >
> > > Are there any reasons why don't we do this by default for virbr0 in libvirt?
> >
> > Because no one has ever suggested it before...
> >
> > Arguably we should just turn off STP on the virbr0 device. Since it is
> > not connected directly to the public LAN[1] there is no risk of network
> > loops and thus spanning tree protocol is pointless for virbr0.
>
> Is there no chance of bridging directly to the outside world by adding a
> real Ethernet device to the bridge?

Yes, you can do that too using regular Fedora initscripts. Warren is
just referring to libvirt's 'Virtual Network' capability which is
NAT based. You can read more about both options for network connectivity
here:

http://wiki.libvirt.org/page/Networking


Regards,
Daniel
--
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Date: Wed, 23 Jul 2008 10:29:10 +0200
From: "=?ISO-8859-1?Q?Javier_G=E1lvez_Guerrero?="
<javier.galvez.guerrero@gmail.com>
To: "Emmet Hikory" <persia@ubuntu.com>
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Thank you so much for your answer.

The application to be developed is just a demonstrator of seamless wireless
mobility and video streaming services ubiquity, no commercial target. So, a=
s
we previously developed a desktop IPTV application in Java and now we need
to include ubiquity capabilities, is good to know what Moblin and Ubuntu
Mobile offers to port (or re-code) the application and add new features
(through wireless drivers information access and multimedia and UI
libraries).

It seems that this can be done more or less in a straight forward way once
the development environment is known. Anyway, if there is any closed access
to drivers or video streams in the Moblin/UME platform, please let me know
as they are essential for my development tasks.

If possible, I would prefer developing in Moblin/UME platform instead of
Windows CE, Symbian or iPhone OS. With Maemo platform (and maybe Android in
a near future), Moblin/UME seems the perfect platform to me, that's where m=
y
interest comes from.


Thank you again,
Javi



2008/7/22 Emmet Hikory <persia@ubuntu.com>

> Javier G=E1lvez Guerrero wrote:
> > What I would like to know is if Ubuntu Mobile allows to develop and add
> my
> > own applications. The application I want to develop should access
> wireless
> > drivers information (i.e. power strength, maybe through madwifi drivers=
)
> and
> > create a GUI with and embeded media player (gstreamer could allow this?=
).
>
> Certainly. Development is essentially the same as development for
> any other Ubuntu flavour, and all tools available in Ubuntu may be
> used for such development (or even tools not in Ubuntu, as long as the
> result works with Ubuntu. Installation on a target requires either
> the generation of custom images for deployment or installation of the
> software package post-installation. For smaller environments (less
> than 4G disk space), it is preferable to create custom images due to
> the use of squashfs in smaller environments. Note that the
> installation system used for the 8.04 release uses squashfs
> unconditionally, so it may be better to re-examine this issue once the
> application development is completed (using post-install packag
> addition for testing).
>
> Having such an application included by default is more
> complicated, and requires it to be of use for the vast majority of
> Ubuntu Mobile users. This is likely best discussed separately once
> such an application has received widespread testing.
>
> > So, can I develop my application in C++ (or Java) to do this? Is it
> > possible? If yes, which libraries/tools are supposed to be used?
>
> Any library available in Ubuntu may be used, although for smallest
> resulting image size it may be best to use C or python and GTK for the
> interface (or any other libraries that are already included in the
> default image).
>
> --
> Emmet HIKORY
> --
> Ubuntu-mobile mailing list
> Ubuntu-mobile@lists.ubuntu.com
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<div dir=3D"ltr">Thank you so much for your answer. <br><br>The application=
to be developed is just a demonstrator of seamless wireless mobility and v=
ideo streaming services ubiquity, no commercial target. So, as we previousl=
y developed a desktop IPTV application in Java and now we need to include u=
biquity capabilities, is good to know what Moblin and Ubuntu Mobile offers =
to port (or re-code) the application and add new features (through wireless=
drivers information access and multimedia and UI libraries). <br>
<br>It seems that this can be done more or less in a straight forward way o=
nce the development environment is known. Anyway, if there is any closed ac=
cess to drivers or video streams in the Moblin/UME platform, please let me =
know as they are essential for my development tasks.<br>
<br>If possible, I would prefer developing in Moblin/UME platform instead o=
f Windows CE, Symbian or iPhone OS. With Maemo platform (and maybe Android =
in a near future), Moblin/UME seems the perfect platform to me, that's =
where my interest comes from.<br>
<br><br>Thank you again,<br>Javi<br><br><br><br><div class=3D"gmail_quote">=
2008/7/22 Emmet Hikory <span dir=3D"ltr">&lt;<a href=3D"mailtoersia@ubunt=
u.com">persia@ubuntu.com</a>&gt;</span><br><blockquote class=3D"gmail_quote=
" style=3D"border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0=
.8ex; padding-left: 1ex;">
<div class=3D"Ih2E3d">Javier G=E1lvez Guerrero wrote:<br>
&gt; What I would like to know is if Ubuntu Mobile allows to develop and ad=
d my<br>
&gt; own applications. The application I want to develop should access wire=
less<br>
&gt; drivers information (i.e. power strength, maybe through madwifi driver=
s) and<br>
&gt; create a GUI with and embeded media player (gstreamer could allow this=
?).<br>
<br>
</div> &nbsp; &nbsp;Certainly. &nbsp;Development is essentially the same as=
development for<br>
any other Ubuntu flavour, and all tools available in Ubuntu may be<br>
used for such development (or even tools not in Ubuntu, as long as the<br>
result works with Ubuntu. &nbsp;Installation on a target requires either<br=
>
the generation of custom images for deployment or installation of the<br>
software package post-installation. &nbsp;For smaller environments (less<br=
>
than 4G disk space), it is preferable to create custom images due to<br>
the use of squashfs in smaller environments. &nbsp;Note that the<br>
installation system used for the 8.04 release uses squashfs<br>
unconditionally, so it may be better to re-examine this issue once the<br>
application development is completed (using post-install packag<br>
addition for testing).<br>
<br>
&nbsp; &nbsp;Having such an application included by default is more<br>
complicated, and requires it to be of use for the vast majority of<br>
Ubuntu Mobile users. &nbsp;This is likely best discussed separately once<br=
>
such an application has received widespread testing.<br>
<div class=3D"Ih2E3d"><br>
&gt; So, can I develop my application in C++ (or Java) to do this? Is it<br=
>
&gt; possible? If yes, which libraries/tools are supposed to be used?<br>
<br>
</div> &nbsp; &nbsp;Any library available in Ubuntu may be used, although f=
or smallest<br>
resulting image size it may be best to use C or python and GTK for the<br>
interface (or any other libraries that are already included in the<br>
default image).<br>
<br>
--<br>
Emmet HIKORY<br>
<font color=3D"#888888">--<br>
</font><div><div></div><div class=3D"Wj3C7c">Ubuntu-mobile mailing list<br>
<a href=3D"mailto:Ubuntu-mobile@lists.ubuntu.com">Ubuntu-mobile@lists.ubunt=
u.com</a><br>
Modify settings or unsubscribe at: <a href=3D"https://lists.ubuntu.com/mail=
man/listinfo/ubuntu-mobile" target=3D"_blank">https://lists.ubuntu.com/mail=
man/listinfo/ubuntu-mobile</a><br>
</div></div></blockquote></div><br></div>

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