[Bridge] Number of addresses limitation

[Bridge] Number of addresses limitation

[François Schmidts]

  Hi,

I'm using bridge-utils to add a bunch of tap interfaces to my computer 
so I can run different qemu vm at the same time without using nat to 
give them network access. It works fine.

But at the same time I would like to add a lot of IPv6s addresses to the 
bridge interface (br0). I find myself limitated to more or less 56 
addresses. If I add one more, one of the addresses already existing just 
disappear from the br0 interface.

Is there something I could do to remove or extent this limitation ?

Best regards,
François Schmidts.

Re: [Bridge] Number of addresses limitation

[Nicolas de Pesloüan]

Le 25/08/2010 16:51, François Schmidts a écrit :
>    Hi,
>
> I'm using bridge-utils to add a bunch of tap interfaces to my computer
> so I can run different qemu vm at the same time without using nat to
> give them network access. It works fine.
>
> But at the same time I would like to add a lot of IPv6s addresses to the
> bridge interface (br0). I find myself limitated to more or less 56
> addresses. If I add one more, one of the addresses already existing just
> disappear from the br0 interface.
>
> Is there something I could do to remove or extent this limitation ?

Did you try the same IPv6 configuration on a normal ethernet NIC ? Do you think this is a bridge 
only related problem ?

	Nicolas.

>
> Best regards,
> François Schmidts.
> _______________________________________________
> Bridge mailing list
> Bridge@lists.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/bridge
>

Re: [Bridge] Number of addresses limitation

[Stephen Hemminger]

On Wed, 25 Aug 2010 21:43:11 +0200
Nicolas de Pesloüan <nicolas.2p.debian@free.fr> wrote:

> Le 25/08/2010 16:51, François Schmidts a écrit :
> >    Hi,
> >
> > I'm using bridge-utils to add a bunch of tap interfaces to my computer
> > so I can run different qemu vm at the same time without using nat to
> > give them network access. It works fine.
> >
> > But at the same time I would like to add a lot of IPv6s addresses to the
> > bridge interface (br0). I find myself limitated to more or less 56
> > addresses. If I add one more, one of the addresses already existing just
> > disappear from the br0 interface.
> >
> > Is there something I could do to remove or extent this limitation ?
> 
> Did you try the same IPv6 configuration on a normal ethernet NIC ? Do you think this is a bridge 
> only related problem ?
> 

Also what tools are you using? Don't use ifconfig (iputils) for IPv6;
only ip command (iproute2) works correctly with multiple addresses.
-- 

Re: [Bridge] Number of addresses limitation

[François Schmidts]

  On 25/08/2010 22:39, Stephen Hemminger wrote:
> On Wed, 25 Aug 2010 21:43:11 +0200
> Nicolas de Pesloüan<nicolas.2p.debian@free.fr>  wrote:
>
>> Le 25/08/2010 16:51, François Schmidts a écrit :
>>>     Hi,
>>>
>>> I'm using bridge-utils to add a bunch of tap interfaces to my computer
>>> so I can run different qemu vm at the same time without using nat to
>>> give them network access. It works fine.
>>>
>>> But at the same time I would like to add a lot of IPv6s addresses to the
>>> bridge interface (br0). I find myself limitated to more or less 56
>>> addresses. If I add one more, one of the addresses already existing just
>>> disappear from the br0 interface.
>>>
>>> Is there something I could do to remove or extent this limitation ?
>> Did you try the same IPv6 configuration on a normal ethernet NIC ? Do you think this is a bridge
>> only related problem ?
>>
> Also what tools are you using? Don't use ifconfig (iputils) for IPv6;
> only ip command (iproute2) works correctly with multiple addresses.
I use something like "ip addr add <prefix>::number/64 dev br0" in a loop 
to add quickly multiple addresses to the bridge.
As far as I have tested it on classic interfaces like eth0, it works 
fine and I can see my 200 addresses (if I added 200 of them) in the 
output of ifconfig.

Re: [Bridge] Number of addresses limitation

[Nicolas de Pesloüan]

Le 25/08/2010 23:49, François Schmidts a écrit :
>    On 25/08/2010 22:39, Stephen Hemminger wrote:
>> On Wed, 25 Aug 2010 21:43:11 +0200
>> Nicolas de Pesloüan<nicolas.2p.debian@free.fr>   wrote:
>>
>>> Le 25/08/2010 16:51, François Schmidts a écrit :
>>>>      Hi,
>>>>
>>>> I'm using bridge-utils to add a bunch of tap interfaces to my computer
>>>> so I can run different qemu vm at the same time without using nat to
>>>> give them network access. It works fine.
>>>>
>>>> But at the same time I would like to add a lot of IPv6s addresses to the
>>>> bridge interface (br0). I find myself limitated to more or less 56
>>>> addresses. If I add one more, one of the addresses already existing just
>>>> disappear from the br0 interface.
>>>>
>>>> Is there something I could do to remove or extent this limitation ?
>>> Did you try the same IPv6 configuration on a normal ethernet NIC ? Do you think this is a bridge
>>> only related problem ?
>>>
>> Also what tools are you using? Don't use ifconfig (iputils) for IPv6;
>> only ip command (iproute2) works correctly with multiple addresses.
> I use something like "ip addr add<prefix>::number/64 dev br0" in a loop
> to add quickly multiple addresses to the bridge.
> As far as I have tested it on classic interfaces like eth0, it works
> fine and I can see my 200 addresses (if I added 200 of them) in the
> output of ifconfig.

I just tested on a 2.6.32 kernel, and get the following results :

Whatever interface I use (bridge or normal Ethernet interface), I'm able to add 200 IPv6 address.

"ifconfig" display all the IPv6 address on the interface.
"ip addr show" only display about 53 of them.

Can you try and ping the 200 IPv6 address from another host, to know whether this is a real IP 
problem or only a display bug. It might be an iproute2 bug on the addr show part.

	Nicolas.

Re: [Bridge] Number of addresses limitation

[Nicolas de Pesloüan]

Le 26/08/2010 21:38, Nicolas de Pesloüan a écrit :
> Le 25/08/2010 23:49, François Schmidts a écrit :
>>     On 25/08/2010 22:39, Stephen Hemminger wrote:
>>> On Wed, 25 Aug 2010 21:43:11 +0200
>>> Nicolas de Pesloüan<nicolas.2p.debian@free.fr>    wrote:
>>>
>>>> Le 25/08/2010 16:51, François Schmidts a écrit :
>>>>>       Hi,
>>>>>
>>>>> I'm using bridge-utils to add a bunch of tap interfaces to my computer
>>>>> so I can run different qemu vm at the same time without using nat to
>>>>> give them network access. It works fine.
>>>>>
>>>>> But at the same time I would like to add a lot of IPv6s addresses to the
>>>>> bridge interface (br0). I find myself limitated to more or less 56
>>>>> addresses. If I add one more, one of the addresses already existing just
>>>>> disappear from the br0 interface.
>>>>>
>>>>> Is there something I could do to remove or extent this limitation ?
>>>> Did you try the same IPv6 configuration on a normal ethernet NIC ? Do you think this is a bridge
>>>> only related problem ?
>>>>
>>> Also what tools are you using? Don't use ifconfig (iputils) for IPv6;
>>> only ip command (iproute2) works correctly with multiple addresses.
>> I use something like "ip addr add<prefix>::number/64 dev br0" in a loop
>> to add quickly multiple addresses to the bridge.
>> As far as I have tested it on classic interfaces like eth0, it works
>> fine and I can see my 200 addresses (if I added 200 of them) in the
>> output of ifconfig.
>
> I just tested on a 2.6.32 kernel, and get the following results :
>
> Whatever interface I use (bridge or normal Ethernet interface), I'm able to add 200 IPv6 address.
>
> "ifconfig" display all the IPv6 address on the interface.
> "ip addr show" only display about 53 of them.
>
> Can you try and ping the 200 IPv6 address from another host, to know whether this is a real IP
> problem or only a display bug. It might be an iproute2 bug on the addr show part.

Another test showed that one can ping the 200 addresses. So this really look like an iproute2 or 
netlink problem, and unrelated to bridge.

	Nicolas.

Re: [Bridge] Number of addresses limitation

[Stephen Hemminger]

On Thu, 26 Aug 2010 23:00:07 +0200
Nicolas de Pesloüan <nicolas.2p.debian@free.fr> wrote:

> Le 26/08/2010 21:38, Nicolas de Pesloüan a écrit :
> > Le 25/08/2010 23:49, François Schmidts a écrit :
> >>     On 25/08/2010 22:39, Stephen Hemminger wrote:
> >>> On Wed, 25 Aug 2010 21:43:11 +0200
> >>> Nicolas de Pesloüan<nicolas.2p.debian@free.fr>    wrote:
> >>>
> >>>> Le 25/08/2010 16:51, François Schmidts a écrit :
> >>>>>       Hi,
> >>>>>
> >>>>> I'm using bridge-utils to add a bunch of tap interfaces to my computer
> >>>>> so I can run different qemu vm at the same time without using nat to
> >>>>> give them network access. It works fine.
> >>>>>
> >>>>> But at the same time I would like to add a lot of IPv6s addresses to the
> >>>>> bridge interface (br0). I find myself limitated to more or less 56
> >>>>> addresses. If I add one more, one of the addresses already existing just
> >>>>> disappear from the br0 interface.
> >>>>>
> >>>>> Is there something I could do to remove or extent this limitation ?
> >>>> Did you try the same IPv6 configuration on a normal ethernet NIC ? Do you think this is a bridge
> >>>> only related problem ?
> >>>>
> >>> Also what tools are you using? Don't use ifconfig (iputils) for IPv6;
> >>> only ip command (iproute2) works correctly with multiple addresses.
> >> I use something like "ip addr add<prefix>::number/64 dev br0" in a loop
> >> to add quickly multiple addresses to the bridge.
> >> As far as I have tested it on classic interfaces like eth0, it works
> >> fine and I can see my 200 addresses (if I added 200 of them) in the
> >> output of ifconfig.
> >
> > I just tested on a 2.6.32 kernel, and get the following results :
> >
> > Whatever interface I use (bridge or normal Ethernet interface), I'm able to add 200 IPv6 address.
> >
> > "ifconfig" display all the IPv6 address on the interface.
> > "ip addr show" only display about 53 of them.
> >
> > Can you try and ping the 200 IPv6 address from another host, to know whether this is a real IP
> > problem or only a display bug. It might be an iproute2 bug on the addr show part.
> 
> Another test showed that one can ping the 200 addresses. So this really look like an iproute2 or 
> netlink problem, and unrelated to bridge.
> 

I just put 2000 addresses onto dummy device and the all show up
with ip addr.  Do you have old tools, the issue is likely the size
of the buffer in netlink interface between ip command and kernel.
Current version has 16K buffer, but it could easily be increased.

Re: [Bridge] Number of addresses limitation

[François Schmidts]

  On 26/08/2010 23:40, Stephen Hemminger wrote:
> On Thu, 26 Aug 2010 23:00:07 +0200
> Nicolas de Pesloüan<nicolas.2p.debian@free.fr>  wrote:
>
>> Le 26/08/2010 21:38, Nicolas de Pesloüan a écrit :
>>> Le 25/08/2010 23:49, François Schmidts a écrit :
>>>>      On 25/08/2010 22:39, Stephen Hemminger wrote:
>>>>> On Wed, 25 Aug 2010 21:43:11 +0200
>>>>> Nicolas de Pesloüan<nicolas.2p.debian@free.fr>     wrote:
>>>>>
>>>>>> Le 25/08/2010 16:51, François Schmidts a écrit :
>>>>>>>        Hi,
>>>>>>>
>>>>>>> I'm using bridge-utils to add a bunch of tap interfaces to my computer
>>>>>>> so I can run different qemu vm at the same time without using nat to
>>>>>>> give them network access. It works fine.
>>>>>>>
>>>>>>> But at the same time I would like to add a lot of IPv6s addresses to the
>>>>>>> bridge interface (br0). I find myself limitated to more or less 56
>>>>>>> addresses. If I add one more, one of the addresses already existing just
>>>>>>> disappear from the br0 interface.
>>>>>>>
>>>>>>> Is there something I could do to remove or extent this limitation ?
>>>>>> Did you try the same IPv6 configuration on a normal ethernet NIC ? Do you think this is a bridge
>>>>>> only related problem ?
>>>>>>
>>>>> Also what tools are you using? Don't use ifconfig (iputils) for IPv6;
>>>>> only ip command (iproute2) works correctly with multiple addresses.
>>>> I use something like "ip addr add<prefix>::number/64 dev br0" in a loop
>>>> to add quickly multiple addresses to the bridge.
>>>> As far as I have tested it on classic interfaces like eth0, it works
>>>> fine and I can see my 200 addresses (if I added 200 of them) in the
>>>> output of ifconfig.
>>> I just tested on a 2.6.32 kernel, and get the following results :
>>>
>>> Whatever interface I use (bridge or normal Ethernet interface), I'm able to add 200 IPv6 address.
>>>
>>> "ifconfig" display all the IPv6 address on the interface.
>>> "ip addr show" only display about 53 of them.
>>>
>>> Can you try and ping the 200 IPv6 address from another host, to know whether this is a real IP
>>> problem or only a display bug. It might be an iproute2 bug on the addr show part.
>> Another test showed that one can ping the 200 addresses. So this really look like an iproute2 or
>> netlink problem, and unrelated to bridge.
>>
> I just put 2000 addresses onto dummy device and the all show up
> with ip addr.  Do you have old tools, the issue is likely the size
> of the buffer in netlink interface between ip command and kernel.
> Current version has 16K buffer, but it could easily be increased.
Thanks for all your answers.

I tested all of this all over again and I couldn't recreate the bug, 
neither on my local machine or on the distant dev server I use for test 
and where the limitation showed up the first time. I added 2000 
addresses on both which were reachable to ping without difficulties.

The problem may have come from a display bug from the tool I used then 
to list IP addresses.

Sorry to have bothered you with an "nonexistent" bug and thanks again.