Tagged/untagged and gretap bridging question.

Greetings list,

Assuming the following network setup of three locations linked by two ethernet over gre (gretap) tunnels.

I am assuming that a broadcast on the local network, if it comes untagged to eth0 will reach both network1 and network2 untagged.

My main question is about a broadcast happening in the tagged portion of (local network). Is there a chance for an ethernet broadcast in vlan 1 on the local network to reach remote network 2? I'm thinking not, but if I tcpdump an interface that has vlans enabled, I will see the tagged packets on eth0. As such I wonder if they will travel through br0 to the remote locations as well, something I would rather avoid.

(local network)
| (remote network 1)

| eth0.1 <--br1--> gre1.1                                       |
+-eth0   <--br0--> gre1-- (l3_to_host1) -- gre0 <--br0--> eth0-+
            |
            +----> gre2 -- (l3-to_host2) -- gre0 <--br0--> eth0-+
  eth0.2 <--br2--> gre2.2                                       |

(remote network 2)

Of interest too is knowing if the tags will survive all the way to remote networks or if I need to enable vlans on the remote gretap and ethernet interfaces as well for them to work.

Alternatively, the setup would look like this:

(local network)

|                                              (remote network 1)
| eth0.1 <--br1--> gre1.1                                       |
| eth0.3 <--br0--> gre1-- (l3_to_host1) -- gre0 <--br0--> eth0-+

+-eth0
eth0.4 <--br3-->gre2 -- (l3-to_host2) -- gre0 <--br0--> eth0-+
eth0.2 <--br2--> gre2.2 |
(remote network 2)

The goal being not to see any untagged frames coming out on the local network from remote locations and instead having them appear in specific local vlans.

So at the core of my questions really is this: Will bridging the untagged portion of an interface that has vlans enabled (eth0 when eth0.x exists) let tagged frames go through to other members of the bridge?

Thanks for your collective wisdom,

Jonathan

In order to strictly control what goes into the bridge and what stay local, you should have a look at the ebtables command.

The following thread might also be useful:

http://www.mail-archive.com/[email protected]/msg01269.html

Nicolas.