Re: xen networking (offtopic)

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Sat, 6 Jun 2020 21:25:57 +0300
    From:        Dima Veselov <kab00m%lich.phys.spbu.ru@localhost>
    Message-ID:  <20200606182557.GA26287@laura>

  | Sorry for off-topic but I always wondered why NetBSD network card
  | is able to talk to others on same bridge?

That should work on any bridge (switch) - correctly configuring the
setup depends upon the requirements of the system, but the whole point
of the bridge (or switch) is to allow systems connected to the various
links (and the host is one of those) communicate with other hosts on
any of the links as if they were all one big flat network.

  | I am asking because in Linux if you assign an IP to interface

This is just a difference in the way the config is done.   NetBSD
has a different model for how the bridge works.   You have to abide
by the rules of the system you're using (which on links is to config
on the bridge itself, on NetBSD it is to config on any one of the
links connected to the bridge (just one) but never the bridge itself.

That's just a style difference.  Once correctly configured they should all
work about the same.

Personally I think the "config the bridge" model is easier to understand,
but once the config is correctly done, it really makes little difference.

  | I don't fully understand mechanics of intercepting packets from output queue
  | of network card, but from the user side of big virtualization system I find
  | much more appropriate to have an IP address on br0 and living switch
  | when wm0 fail even if it cost me some time of raising it.

The delays ae a different issue, NetBSD can run spanning tree on the
bridge (actually, on individual ports of the switch) too, and that
protocol does take time to run ... just it defaults to off on NetBSD
(which for most users is the better choice, though defaulting to on is the
safer one - that always works, just with a startup delay - not running
the spanning tree will cause problems if the topology has loops).

kre