Re: kern/60055: bridge doesn't work well with urtwn(4)

["Takashi Yamamoto via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR kern/60055; it has been noted by GNATS.

From: Takashi Yamamoto <imuwoto2%gmail.com@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, 
	imuwoto%gmail.com@localhost
Subject: Re: kern/60055: bridge doesn't work well with urtwn(4)
Date: Wed, 4 Mar 2026 22:10:22 +0900

 hi,
 
 On Wed, Mar 4, 2026 at 9:50=E2=80=AFPM Michael van Elst via gnats
 <gnats-admin%netbsd.org@localhost> wrote:
 >
 > The following reply was made to PR kern/60055; it has been noted by GNATS=
 .
 >
 > From: mlelstv%serpens.de@localhost (Michael van Elst)
 > To: gnats-bugs%netbsd.org@localhost
 > Cc:
 > Subject: Re: kern/60055: bridge doesn't work well with urtwn(4)
 > Date: Wed, 4 Mar 2026 12:49:22 -0000 (UTC)
 >
 >  gnats-admin%NetBSD.org@localhost ("imuwoto%gmail.com@localhost via gnats") writes:
 >
 >  >for some reasons, adding urtwn0 as a physical port of a bridge(4) didn'=
 t work.
 >  >other members of the bridge: vether0, tap (for qemu/nvmm)
 >  >namely a host on the urtwn0's segment <-> tap/vether couldn't communica=
 te.
 >
 >  You cannot bridge wifi.
 >
 >  To participate in a bridge, the interface needs to transmit with multipl=
 e
 >  MAC addresses, depending on what packet the sender belongs too.
 >
 >  But in wifi, the MAC address is part of the client identification. The
 >  accesspoint won't accept packets from a different MAC address, even
 >  when the interface could chose one.
 >
 >  wifi interfaces that know hostap mode do support multiple MAC
 >  addresses and there is also a modified wifi protocol (used for
 >  bridging access points) that allows such packets. But it's
 >  not supported by many regular clients.
 >
 >  You may tunnel traffic through L2TP if you have another machine
 >  on the wired network. That's how I usually solve the problem when
 >  running guests on a wifi-only notebook. Another is to run guests
 >  in their own network and make the host a NAT router.
 >
 
 thank you for explanation.
 
 the following sentence in bridge(4) made me think it was supposed to work.
 what does it actually mean?
 
      A bridge can be used to provide several services, such as a simple
      802.11-to-Ethernet bridge for wireless hosts, and traffic isolation.