[ovs-discuss] Difference between access ovs port and native ovs untagged port

Duankebo (Frank) duankebo at huawei.com
Mon May 4 12:40:00 UTC 2015

Dear guys:
	I have an ovs working as both L2 switch and L3 router, L2 switch is a typical learning switch(using "normal" flow entry) and works fine.

    To L3 router function, things become difficult. In my setting, each port on ovs is access port, when I route one packet from one port to

    another port with a difference access vlan tag, I have to modify the vlan tag to that of the destination port, then use NORMAL action to

    forwarding the packet to the destination port.

       |               |
       |      OVS      |
       |               |
          |       | 
          |       |
         VM2    VM1

	Showing in the diagram above, VM2 has a access vlan of 20, VM1 has a access vlan of 10. The flow entry looks like this:

		In_port=1, dl_dst=gateway_mac, nw_dst=VM2_IP, actions=mod_dl_dst:VM2_MAC, mod_vlan_vid:20, output:NORMAL

    To my surprise, the packets from VM1 to VM2 were dropped, Log of ovs said I can't modify vlan id of an access port. 

    By changing VM1 and VM2's port type to "NATIVE-UNTAGGED", I can solve this problem, but I'm unsure of the different between access port and native-untagged

    port, are their behavior exactly the same? Can I replace a access port with a native-untagged port?

    The mail is a bit long and the problem somewhat complicated, thank you for your patience!

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