1
+-------------+             +--------------------+         +-----------------+
|             |             |                    |         |                 |
|   Gateway   +--------VLAN-+ Some Linux machine +-TAP-----+  A part of LAN  |
|             |             |                    |         |                 |
+-------------+             +--------------------+         +-----------------+

For some reason I have to use a linux machine as a bridge to connect 2 parts of my LAN. The linux machine is connected to a bridge on gateway by VLAN, and that part of LAN is a tap device.

Before this setup, I've tested my Linux machine can reach both side of the network by assigning IPs to each interface and ping the other side. It works well.

Then I created a bridge to connect the VLAN interface and tap interface, and assigned the IP to the bridge. Then I tested connectivity:

  • Gateway ping Linux: NO
  • Gateway ARP-ping Linux: OK
  • Gateway ping LAN: NO
  • Gateway ARP-ping LAN: OK
  • Linux ping Gateway: NO
  • Linux ARP-ping Gateway: NO
  • Linux ping LAN: OK

I noticed the bridge inherited MAC address of tap interface. When I manually change it to the MAC address of VLAN interface, now Linux can ping both Gateway and LAN, but LAN and Gateway is still not connected.

What can I do to make gateway reachable from LAN?

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