AOS-CX Switch Simulator

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Spanning-tree, Port in blocking allow RX traffic?

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  • 1.  Spanning-tree, Port in blocking allow RX traffic?

    Posted Dec 23, 2021 04:08 AM
    I can't find any limitations regarding spanning-tree ports in state blocking in the release notes.

    I have tried using both 10.08 and 10.09 on EVE-NG PRO 4.0.1-65 using simple and more advanced setup. With just switches the protocols looks good, but when I introduces VPC in the lab the traffic loops.

    I understand that the enforcement of discarding packets on blocked ports in the real switches are done by the hardware.

    If the observed behavior is by design it would be nice to have it in the release notes, if it's by accident it should probably be fixed. If I'm the only one observing this please guide me how to this right.

    To reproduce just import Basic Spanning Tree lab, copy the configurations from the PDF in to the switches. Add a VPC to SwitchA interface 1/1/9, configure the interface as access in vlan 1. Start a Capture on interface 1/1/2 on SwitchC. Add a IP address on the VPC and observe the capture. Looking at the counters on the interfaces 1/1/1 and 1/1/2 it looks like RX packets on 1/1/1 in blocking is TX on 1/1/2.


    Arne Opdal

  • 2.  RE: Spanning-tree, Port in blocking allow RX traffic?

    Posted Jan 07, 2022 09:01 AM

    This is a current limitation of the simulator.
    The labs are valid only as far as observing STP states and  topology. However, passing endpoint traffic causes undefined results.

    Kamal Takodra
    If my post was useful accept solution and/or give kudos

  • 3.  RE: Spanning-tree, Port in blocking allow RX traffic?

    Posted Jan 07, 2022 09:14 AM
    Kamal, thanks for enlighten me!

    And it's nice to find out I'm not doing this wrong ;-)

    I think it would be nice to have this in the limitation section of the release notes. And hopefully at some time in the future discard RX on blocked ports could be implemented.

    Arne Opdal