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List:       linux-bridge
Subject:    Re: [Bridge] Ethernet tunnel over ppp with bridge?
From:       Lennert Buytenhek <buytenh () gnu ! org>
Date:       2002-02-06 9:50:18
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Hi,

When tunneling ethernet with linux, the big question is: do you want to
do RFC-compatible ethernet-over-ppp or not?

If so, you're out of luck.  As far as I know, the linux ppp implementation
doesn't support ethernet encapsulation.

If it doesn't matter, it's your lucky day!  Get a copy of vtund
(http://vtun.sf.net/), and setup an ethernet tunnel between the two
tunnel endpoints.  This is a tunnel that runs over plain IP, so it will
work between any two hosts that have IP connectivity.  After you get
the ethernet tunnel running, enslave the ethernet tunnel device together
with the physical ('real') ethernet port to a bridge port group and move
any IP addresses you had on the physical port to the bridge device.

Hope this helps.


cheers,
Lennert


On Tue, Feb 05, 2002 at 07:51:33PM -0800, David Ashley wrote:

> I'm not sure if this is the right place to ask this, (sorry). I looked at
> the list archives and found some mention of ppp not being supported, but
> perhaps something is possible.
> 
> The setup is like this:
> 
> 1) [Computer]
>        |  172.16.0.30
>        | (via 100baseT ethernet)
>        |  172.16.0.31
> 2) [DSL daughter board in computer]
>        | 10.10.10.2
>        |
>        | (via DSL ppp link)
>        |
>        | 10.10.10.1
> 3) [DSL server]
>        | 192.168.0.50
>        | (via ethernet)
>        | 192.168.0.*
> 4) {LAN/gateway to internet, etc}
> 
> Currently node #1 and #2 have IP addresses on their own subnet. #2 has an
> ip address for its end of the PPP link also. I want node #2 not only have
> its IP address associated with the ppp link. So packets coming from its
> ethernet port get relayed directly over the ppp link without any change, and
> packets arriving from the ppp link get sent to the ethernet port without any
> change. The daughter board is running linux, and its ppp link is brought up,
> then it is assigned an ip address for its ethernet port. I want to avoid that,
> so its ethernet port is transparent.
> 
> I was wondering if it was possible to bridge the ppp and the ethernet on
> node #2 together, after the ppp link is established. So the new bridge would
> have the ip address of that end of the ppp link (10.10.10.2). I don't want
> there to be the 172.16.0.31 ip address assigned to the daughter board.
> 
> If this isn't possible with bridging, perhaps there is some other way to
> do it with packet forwarding? But it would have to be forwarding at an
> ethernet level I think.
> 
> I can't change the link between #2 and #3, but I can run whatever I want on
> nodes #1 and #2 since they're running linux.
> 
> Thanks for your thoughts! Please cc me on all responses.
> 
> Dave Ashley
> dash@xdr.com
> 

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