I need to measure the performance of a linux network bridge (https://wiki.archlinux.org/title/Network_bridge) on a particular machine (machine A). My initial idea for a setup looked like this:
+-------------+
| machine A |
+-------------+
| eth0 | eth1 |
+-------------+
^ ^
+--------------+ | | +--------------+
| machine B |<----------------+ +-------------->| machine C |
+--------------+ +--------------+
With machine A acting as the switch (bridging eth0 and eth1), I'd measure the link between machine B and machine C using something like iperf. The trouble is, I don't have access to any suitable machines to play the roles of machine B and machine C. Someone suggested the following setup instead, using machine A as a stand-in for both (as it has more than enough physical interfaces):
+---------------------------+
| machine A |
+---------------------------+
| eth0 | eth1 | eth2 | eth3 |
+---------------------------+
^ ^ ^ ^
| | | |
+------+ +------+
this time bridging eth1 and eth2, and then measuring the performance between eth0 and eth3. To me, this seems a bit silly at first, but I can't say with certainty that it wouldn't work. My concern is that machine A would figure out that the traffic between eth0 and eth3 can be routed internally, bypassing the bridge and physical links.
Am I right or wrong, will this setup work?
