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Re: bridges with multiple static IPs or DHPC - how to configure?



On Wed, Jun 4, 2014 at 2:00 PM, Steffen Dettmer
<steffen.dettmer@gmail.com> wrote:


> how to configure a bridge with multiple static IPs and/or DHPC
> via /etc/network/interfaces?
>
> I tried many combinations, but I didn't find any working one.
>
> Of course everything works as expected when configuring manually
> with "ip", "brctl" etc.

Can you post your manual configuration?

(By the way, you don't need brctl; "ip link" can create bridges.)


> Any working example would be great!
>
> The rest of the mail discusses what I tried so far.
>
> Yes, I read man bridge-utils-interfaces(5), but it has simple
> examples only (single static IP or no IP). The man page tells,
> interfaces used as bridge_ports
>
>    "are the  interfaces  that  are  part  of  the  bridge,  and
>    they shouldn't  have  any  stanzas defining them on the
>    interfaces file"          -- man bridge-utils-interfaces(5)
>
> but this is wrong. There must be a stanza like
>
>   auto eth3.14
>     iface eth3.14 inet manual
>
> otherwise no bridge can use it any only gives an error message
> like "interface eth3.14 does not exist!".

I suspect that the bridge-utils-interfaces man page refers to physical
interfaces. You might want to file an RFE bug for it to work for
vlan-tagged interfaces so that:

iface br0.100
bridge_ports eth0.100

creates and brings up eth0.100 and br0, as well as br0.100.


> For an ordinary ethernet interface, the following works:
>
>   auto eth3.10
>   iface eth3.10 inet static
>     address 10.72.9.17
>     netmask 255.255.255.248
>   iface eth3.10 inet static
>     address 10.72.9.25
>     netmask 255.255.255.248
>
> For bridges, it is not clear how to use multiple stanzas for
> multiple IPs; it seems, the options to create the bridge and to
> add IPs to it are somehow mixed.
> There are options like bridge_ports. They have to be in each
> "iface br0" stanza?
>
>   (Experiments show that "bridge_ports" are accumulated (probably
>   simply because each stanza brctl addif each, in total producing
>   the desired result), but other options such as bridge_maxwait
>   are not.)
>
> The same approach as for Ethernet does not work for Bridges:
>
>   iface br1 inet static
>     address 10.1.1.1
>     netmask 255.255.255.248
>     bridge_ports eth3.10
>     bridge_maxwait 0
>   iface br1 inet static
>     address 10.1.1.9
>     netmask 255.255.255.248
>     bridge_ports eth3.11
>     bridge_ports eth3.12
>     bridge_maxwait 0
>
> This adds all interfaces to br1, but only the IP address from the
> last block.

I can't see the above working. When I've bridged vlan-tagged
interfaces, I've used one bridge per vlan.

If you want to add more than one ip address to an untagged bridge.

This might work:

iface br0 inet static
address 10.1.1.1
netmask 255.255.255.248
gateway 10.1.1.254
bridge_ports eth0
bridge_ports eth1

iface br0 inet static
address 10.1.1.2
netmask 255.255.255.248
gateway 10.1.1.254
bridge_ports eth0
bridge_ports eth1

And this will work:

iface br0 inet static
address 10.1.1.1
netmask 255.255.255.248
gateway 10.1.1.254
bridge_ports eth0
bridge_ports eth1
up ip addr add 10.1.1.2/29 dev br0
down ip addr del 10.1.1.2/29 dev br0


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