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Any limitations for vQFX spanning tree ?

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  • 1.  Any limitations for vQFX spanning tree ?

    Posted 12-02-2020 12:44
    I am trying to practice spanning tree with a few vQFXs.  Anyone knows any limitations for this ?

    thanks !!

    root@EX1# show protocols mstp | display set
    set protocols mstp configuration-name jncie
    set protocols mstp revision-level 1
    set protocols mstp interface xe-0/0/10
    set protocols mstp interface xe-0/0/11
    set protocols mstp interface ae10
    set protocols mstp msti 1 bridge-priority 4k
    set protocols mstp msti 1 vlan 1-199
    set protocols mstp msti 2 bridge-priority 4k
    set protocols mstp msti 2 vlan 200-299

    root@EX2# show protocols mstp | display set
    set protocols mstp configuration-name jncie
    set protocols mstp revision-level 1
    set protocols mstp bridge-priority 8k
    set protocols mstp interface xe-0/0/10
    set protocols mstp interface xe-0/0/11
    set protocols mstp interface ae10
    set protocols mstp msti 1 bridge-priority 8k
    set protocols mstp msti 1 vlan 1-199
    set protocols mstp msti 2 vlan 200-299

    based on the above configuration, I expect to see EX2 to be root bridge for msti 1, right ?   But I have the following:


    Anything I missed? or some limitation for vQFX for this ?

    Also only when I configured EX2 to CST root,  can I move msti root to EX1, or EX1 is always root for all MSTi.

    Seems the bridge-priority never takes effect on EX2.


    thanks in advanced for any insights.


  • 2.  RE: Any limitations for vQFX spanning tree ?
    Best Answer

    Posted 12-02-2020 14:27

    Hi gongyayu .

    Unless I am misreading your question, I think that you are a bit confused about the bridge priority, please note that regarding this knob to influence the root bridge election, the lowest value will be the one taking over, I mean lowest will be elected as the root bridge. 

    Checking the config provided I can see the root bridge will be as expected EX1 , not EX2 as you mentioned as EX1 has a priority of 4k.


    Please see below :

    The root bridge is selected by manually configuring its bridge priority to a low value. 32768 is the default value out of a range from 0 to 61440.

    I hope my brief input helps you.

    Kind regards


  • 3.  RE: Any limitations for vQFX spanning tree ?

    Posted 12-02-2020 16:45
    thanks a lot !!

    I missed that line configuration.


  • 4.  RE: Any limitations for vQFX spanning tree ?

     
    Posted 12-02-2020 18:45
    Spanning Tree!! 

    "I think that I shall never see

    A graph more lovely than a tree.
    A tree whose crucial property
    Is loop-free connectivity..." 


    Regards,

    ------------------------------
    Yasmin Lara
    Juniper Ambassador
    JNCIE-SP, JNCIE-ENT, JNCIE-DC, JNCIE-SEC
    JNCDS-DC, JNCIA-DevOps, JNCIP-CLOUD, CCNP-ENT
    ------------------------------



  • 5.  RE: Any limitations for vQFX spanning tree ?

    Posted 12-02-2020 19:27
    thanks so much !!  Nice materials.


  • 6.  RE: Any limitations for vQFX spanning tree ?

    Posted 12-02-2020 21:48


    EX2 should be root for MSTi 2 ?   Or something I missed ?

    thanks a lot in advanced !!



  • 7.  RE: Any limitations for vQFX spanning tree ?

    Posted 12-02-2020 21:55
    After I switched CST root to EX2, everything seems right .





  • 8.  RE: Any limitations for vQFX spanning tree ?

    Posted 12-02-2020 22:06
    But I switched CST root to EX1, seems not right again.  Hopefully this is the vQFX firmware. Might be something I missed.

    thanks for any insights !!


  • 9.  RE: Any limitations for vQFX spanning tree ?

    Posted 12-05-2020 20:12
    Today I tried on two physical EX switches. I got the following and do not understand why EX1 is not root bridge for MSTi 1




    Why is the local bridge ID not the default priority ?

    After I moved the CST root bridge to EX1,  MSTi 1 local bridge ID changes to be default


    I definitely miss something here.  Appreciate any coaching !!

    thanks in advance !!


  • 10.  RE: Any limitations for vQFX spanning tree ?

     
    Posted 12-05-2020 23:57
    Since you are NOT configuring a bridge priority under MSTI 1 it is using the priority that you configured under protocols msti. 

    Regards,

    ------------------------------
    Yasmin Lara
    Juniper Ambassador
    JNCIE-SP, JNCIE-ENT, JNCIE-DC, JNCIE-SEC
    JNCDS-DC, JNCIA-DevOps, JNCIP-CLOUD, CCNP-ENT
    ------------------------------



  • 11.  RE: Any limitations for vQFX spanning tree ?

    Posted 12-06-2020 00:05
    Oh, thanks for coaching.


  • 12.  RE: Any limitations for vQFX spanning tree ?

    Posted 12-06-2020 19:06
    thanks so much for coaching. I definitely missed this point. right now everything is what I expect to see.


  • 13.  RE: Any limitations for vQFX spanning tree ?

     
    Posted 12-06-2020 22:13
    You are welcome!  Keep it up, you are doing great!

    ------------------------------
    Yasmin Lara
    Juniper Ambassador
    JNCIE-SP, JNCIE-ENT, JNCIE-DC, JNCIE-SEC
    JNCDS-DC, JNCIA-DevOps, JNCIP-CLOUD, CCNP-ENT
    ------------------------------