[libvirt-users] STP default behavior for bridged (off) and NAT (on) networking in libvirt

[Francesco Pretto]

Hello,

when talking about networking in hypervisors, it's easy to distinguish
the two classic configurations, NAT and bridged, and the official
libvirt wiki does exactly in this way here [1]. NAT networking is
already configured by libvirt creating a bridge called libvirt0, while
bridged networking have to be configured manually by the user.

The libvirt0 bridge for NAT networking is default configured in this way:
STP=on
MAXWAIT=0

While suggested br0 bridge for bridged networking is configured in this way:
STP=off
MAXWAIT=5

Please, can you explain me why STP is on for NAT and should be off for
bridged networking? It seems much easier to me to create loops when
using bridged networking than NAT. Moreover, reading this old debian
bug about complaints of MAXWAIT != 0 when STP off, I'm wondering if
the suggested configurations aren't actually switched.

Thanks,
Francesco

[1] http://wiki.libvirt.org/page/Networking
[2] http://www.mail-archive.com/debian-bugs-dist@lists.debian.org/msg700924.html