Stephen Hemminger wrote:
On Fri, 01 Jul 2005 11:59:08 +0200
Antonio Pinizzotto <antonio.pinizzotto@xxxxxxxxxx> wrote:
Hi all.
I would need to use a single physical interface on a Linux box to manage
two different IP addresses (belonging to two separate logical subnets)
with two different MAC address. (I need to emulate te presence of two
separate physical interfaceses for a PC on the same LAN, at layer 2 and
layer 3).
Is it possible to use the linux ethernet bridging code and two tap
interfaces for this purpose?
Here is a picture of what I need to do.
LAN__________________________________
|
| eth0 (no IP)
________|________
| |
| br0 |
| (no IP) |
|_________________|
tap0 | | tap1
192.168.40.1/24 | | 192.168.30.1/24
MAC_0 | | MAC_1
__|________|__
| |
| PC |
| |
|______________|
I would need this picture to be equivalent to this one:
LAN__________________________________
eth0 | | eth1
192.168.40.1/24 | | 192.168.30.1/24
MAC_0 | | MAC_1
__|________|__
| |
| PC |
| |
|______________|
I tried but it doens't work. I don't know if it's not contemplate or if
I did a wrong configuration.
For example, on tap0, using tcpdump, I see all the L2 broadcast frames
going on the LAN; but on the counters of "ifconfig tap0" all of them are
considered dropped. No packet is counted as transmitted or received,
also if I try to ping from or to tap0.
The tap interface starts to transmit/receive pachets only if it is
connected to some process like qemu or openvpn.
Maybe, it is not possibile for tap interface to be used directly by the
linux os?
Stop abusing bridging. People keep trying these wacky multiple
network things and they won't work. Bridging really can't handle anything
with multiple interfaces that could possibly create a forwarding loop.
Dear Stephen,
probably my pictures or descriptions were not so clear.
I don't want abuse bridging.
As you can see in the second picture (of the previous e-mail) I just
would like to replicate the real topology (in which there are not loops
because each physical interface has its own subnet) using software
interfaces, taps. Moreover in the second picture no bridging is enabled
on the PC.
It is just an experiment to understand how the various software pieces
works togheter.
Below I tried to draw a clearer picture.
The first one is what I would like to get.
The second one is what I have.
LAN______________________________________________
|
| eth0 (no IP)
_____________________|________________________
| | Linux Box (PC)|
| ________|________ |
| | | |
| | br0 | |
| | (no IP) | |
| |_________________| |
| tap0 | | tap1 |
| 192.168.40.1/24 | | 192.168.30.1/24 |
| MAC_0 | | MAC_1 |
| ___|________|____ |
| | | |
| | OS TCP-IP stack | |
| | | |
| |_________________| |
| | | | | |
| | | | | |
| Processes |
| |
| |
|______________________________________________|
I would need the first picture to be equivalent to the next one:
LAN_____________________________________________
eth0 | | eth1
192.168.40.1/24 | | 192.168.30.1/24
MAC_0 | | MAC_1
_________________|________|___________________
| | | Linux Box (PC)|
| ___|________|____ |
| | | |
| | OS TCP-IP stack | |
| | | |
| |_________________| |
| | | | | |
| | | | | |
| Processes |
| |
| |
|______________________________________________|
Bye
Antonio
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