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Basic spanning tree RPVST config ?

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  • 1.  Basic spanning tree RPVST config ?

    Posted Dec 01, 2021 12:11 PM
    I am moving from Cisco to Aruba, and I am wondering how much configuration is needed for spanning tree RPVST to work properly.

    In general it seems like I don't really need to do much at all and the defaults may be good enough. But I just want to check and make sure.

    I am not seeing any problems with this very minimalist configuration, but it is vaguely disconcerting to see that both the primary 10 gigabit fiber and the 2 gigabit backup path are both listed as forwarding in the spanning tree status.

    Is it permitted to have redundant paths both forwarding between switches without creating broadcast storm loops?

    Switch 5412R in the Server Room, root switch, edge ports all on module B
    spanning-tree
    spanning-tree mode rapid-pvst
    spanning-tree vlan 1 priority 0
    spanning-tree vlan 5 priority 0
    spanning-tree B1-B24 bpdu-protection
    spanning-tree bpdu-protection-timeout 300 priority 0


    Backbone ports between closets:
    A23 - 10 gigabit multimode LRM fiber to switch Upper Level
    Trk1 / A19-A20 - 2 gigabit 802.1Q trunk on two CAT5 to switch Upper Level (failover backup path)


    Switch 5412R in the Upper Level of the building, edge ports all on module B
    spanning-tree
    spanning-tree mode rapid-pvst
    spanning-tree B1-B24 bpdu-protection
    spanning-tree bpdu-protection-timeout 300 priority 0

    Backbone ports between closets:
    A23 - 10 gigabit multimode LRM fiber back to switch Server Room
    Trk1 / A19-A20 - 2 gigabit 802.1Q trunk on two CAT5 back to switch Server Room (failover backup path)

    ===============================


    Server room: show spanning-tree port A23

    Spanning Tree Information

    STP Enabled [No] : Yes
    Mode : RPVST
    RPVST Enabled VLANs : 1,5

    Switch MAC Address : 883a30-e80200

    Port : A23
    Status : Up Port Type : SFP+LRM
    BPDU Protection : No BPDU Filtering : No
    Root Guard : No TCN Guard : No
    Loop Guard : No Admin Edge Port : No
    Admin PointToPoint MAC : Yes

    VLAN Port Port Port Designated Hello Oper Oper
    ID Path-Cost Priority State Bridge Time Edge PtP
    ------ ---------- --------- ---------- ----------------- ----- ----- ------
    1 2000 128 Forwarding 883a30-e80200 2 No Yes
    5 2000 128 Forwarding 883a30-e80200 2 No Yes

    =====================================


    Server Room: show spanning-tree port Trk1

    Spanning Tree Information

    STP Enabled [No] : Yes
    Mode : RPVST
    RPVST Enabled VLANs : 1,5

    Switch MAC Address : 883a30-e80200

    Port : Trk1
    Status : Up Port Type : SFP+LRM
    BPDU Protection : No BPDU Filtering : No
    Root Guard : No TCN Guard : No
    Loop Guard : No Admin Edge Port : No
    Admin PointToPoint MAC : Yes

    VLAN Port Port Port Designated Hello Oper Oper
    ID Path-Cost Priority State Bridge Time Edge PtP
    ------ ---------- --------- ---------- ----------------- ----- ----- ------
    1 20000 64 Forwarding 883a30-e80200 2 No Yes
    5 20000 64 Forwarding 883a30-e80200 2 No Yes


  • 2.  RE: Basic spanning tree RPVST config ?
    Best Answer

    EMPLOYEE
    Posted Dec 02, 2021 05:47 AM
    Hallo

    I am not seeing any problems with this very minimalist configuration, but it is vaguely disconcerting to see that both the primary 10 gigabit fiber and the 2 gigabit backup path are both listed as forwarding in the spanning tree status.

    Is it permitted to have redundant paths both forwarding between switches without creating broadcast storm loops?

    The redundant path with higher cost will be blocked however it is blocked only on one side of the link not on both sides. Typically in an STP topology a redundant link between 2 switches is blocked by the switch who has the path with higher cost in the root bridge. The Server Room Switch is Root Bridge in both VLANs 1 and 5 so it means that the other switch (Upper Level) should set the redundant path to blocking state. Did you check the same on the Upper Level switch?

    ------------------------------
    Emil Gogushev
    ------------------------------

    Original Message


  • 3.  RE: Basic spanning tree RPVST config ?

    Posted Dec 07, 2021 10:24 AM
    Thank you, you are correct. If I check the "upstream" switch ports, it shows me that the lower speed redundant connection to that switch is currently blocking.


    Original Message