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  • 1.  BPDU LoadBalancing with ae interface

     
    Posted 09-07-2020 16:48

    Dear community,

     

    Does someone know how BPDU are sent and load balance over aggregate ethernet interface  ?

     

    If I have an ae52 interface with 4 member (int1, int2, int3 and int4), where the STP BPDU  will be sent ? int1 ? int2 ? int3 or int 4 ?

     

    Does it apply to QFX5100 ? QFX5100 mode VCF ?

     

    Thanks for your help

     

    Salah



  • 2.  RE: BPDU LoadBalancing with ae interface

    Posted 09-07-2020 16:57

    HI, since this is locally originated packet, then first interface in lag should be selected.



  • 3.  RE: BPDU LoadBalancing with ae interface

     
    Posted 09-09-2020 15:07

    Thanks for you reply Akushner.

     

    What do you mean by first interface in the LAG ? first interface that show in "show lacp interface aeX" ? smallest interface snmp index ? first interface in manming order ? Let make it simple: which one here :

     

    boss@device> show lacp interfaces ae209 
Aggregated interface: ae209
    LACP state:       Role   Exp   Def  Dist  Col  Syn  Aggr  Timeout  Activity
      xe-10/0/6      Actor    No    No   Yes  Yes  Yes   Yes     Fast    Active
      xe-10/0/6    Partner    No    No   Yes  Yes  Yes   Yes     Slow    Active
      xe-10/0/7      Actor    No    No   Yes  Yes  Yes   Yes     Fast    Active
      xe-10/0/7    Partner    No    No   Yes  Yes  Yes   Yes     Slow    Active
      xe-10/0/8      Actor    No    No   Yes  Yes  Yes   Yes     Fast    Active
      xe-10/0/8    Partner    No    No   Yes  Yes  Yes   Yes     Slow    Active
      xe-9/0/0       Actor    No    No   Yes  Yes  Yes   Yes     Fast    Active
      xe-9/0/0     Partner    No    No   Yes  Yes  Yes   Yes     Slow    Active
      xe-9/0/4       Actor    No    No   Yes  Yes  Yes   Yes     Fast    Active
      xe-9/0/4     Partner    No    No   Yes  Yes  Yes   Yes     Slow    Active
      xe-9/0/8       Actor    No    No   Yes  Yes  Yes   Yes     Fast    Active
      xe-9/0/8     Partner    No    No   Yes  Yes  Yes   Yes     Slow    Active
      xe-10/0/0      Actor    No    No   Yes  Yes  Yes   Yes     Fast    Active
      xe-10/0/0    Partner    No    No   Yes  Yes  Yes   Yes     Slow    Active
      xe-9/0/7       Actor    No    No   Yes  Yes  Yes   Yes     Fast    Active
      xe-9/0/7     Partner    No    No   Yes  Yes  Yes   Yes     Slow    Active
    LACP protocol:        Receive State  Transmit State          Mux State 
      xe-10/0/6                 Current   Slow periodic Collecting distributing
      xe-10/0/7                 Current   Slow periodic Collecting distributing
      xe-10/0/8                 Current   Slow periodic Collecting distributing
      xe-9/0/0                  Current   Slow periodic Collecting distributing
      xe-9/0/4                  Current   Slow periodic Collecting distributing
      xe-9/0/8                  Current   Slow periodic Collecting distributing
      xe-10/0/0                 Current   Slow periodic Collecting distributing
      xe-9/0/7                  Current   Slow periodic Collecting distributing

     

    Other question :

     

    What happen when this interface flap ? does the BPDU rollback to this interface ? or it stays to the next one ?

     

    Thanks

     

    Salah



  • 4.  RE: BPDU LoadBalancing with ae interface
    Best Answer

    Posted 09-09-2020 18:01

    Hi Salah, 

     

    I hope you are having a nice day!

     

    Regarding your questions:

     

    • All RE generated packets that traverse the LAG, such as protocol control traffic, will use the lowest member link.

    So if you have a lag made with ge-0/0/0 ge-0/0/1 and ge-0/0/2 the control traffic will go thru ge-0/0/0 so the lowest member link is let's say closet link to 0/0/0 so if ge-0/0/0 fails ge-0/0/1 will start sending RE traffic.

     

    What happen when this interface flap ? does the BPDU rollback to this interface ? or it stays to the next one ?

     

    I couldn't find anything related to this, but I would say it will go back, because every time the RE traffic hits the AE, the algorithm will say use the lowest member.

     

    Be safe!

    Warm regards,

    Pablo Restrepo

     

     

    If this solves your problem, please mark this post as "Accepted Solution" so we can help others too.



  • 5.  RE: BPDU LoadBalancing with ae interface

    Posted 09-09-2020 18:01

    that should be lowest one (xe-9/0/0). 

    After interface (xe-9/0/0) flaps and came up all host outbound packets will be send from this interface again



  • 6.  RE: BPDU LoadBalancing with ae interface

     
    Posted 09-21-2020 14:56

    Hi All

     

    Sorry for the late reply and thanks all of you for the answer. Despite my strong Juniper experience, It was something I didn't know.

     

    We have always something to learn 😉

     

    Thanks again

     

    S