On 2016-06-10 03:02, Simon Walter wrote:

    [snip]

> Though, you do need to specify the bridge to be created and destroyed,
> which is something I thought was done automatically. It is when there
> are ports specified. As Rainer pointed out, when bridge_ports is "none",
> then the bridge device is created automatically and one not need to
> create it and destroy it pre-up and post-down. Though it seems to do it
> explicitly is a bit faster. I am not sure which is better or if there
> are any side affects.

The only side-effect are the extra messages during ifup with
"bridge_ports none":

iface testbr1 inet static
          bridge_ports none
          address 10.91.0.1
          netmask 255.255.0.0
          network 10.91.0.0
          broadcast 10.91.255.255
          bridge_stp off           # disable Spanning Tree Protocol
          bridge_waitport 0        # no delay before a port becomes 
available
          bridge_fd 0              # no forwarding delay
          up        ip link set $IFACE up
          down      ip link set $IFACE down

# ifup testbr1
Waiting for a max of 0 seconds for # no delay before a port becomes
available to become available.
Waiting for testbr1 to get ready (MAXWAIT is 2 seconds).
#

I just happen to prefer the pre-up addbr/post-down delbr method. No
"Waiting" messages and a tad quicker. Other than that, both ways are
equivalent and work equally well.

Cheers