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Can MC-LAG & RSTP coexist at same time on QFX10k?

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  • 1.  Can MC-LAG & RSTP coexist at same time on QFX10k?

    Posted 08-27-2020 05:32

    Hi all,

     

     

    May i know whether the MC-LAG and RSTP can coexists at same time? If yes then is it the back-to-back between Spine / Core Switch need to participate in RSTP also?

     

     

    Thanks and appreciate any feedback



  • 2.  RE: Can MC-LAG & RSTP coexist at same time on QFX10k?

    Posted 08-27-2020 06:42

    Hello 

     

    STP has to be disabled in the ICL, however if your downstream device is a switch, you should configure stp on the mc-ae interfaces with the lowest priority to make the MC peers the root bridge.

     

    If your downstream device is a host/server, you should configure the mc-aes as edge ports.

     

    Regards,



  • 3.  RE: Can MC-LAG & RSTP coexist at same time on QFX10k?

    Posted 08-27-2020 07:26

    Hi rbabraham,

     

    As i'm understand, on RSTP between Core/Spine that interface must need to participate in RSTP protocol. If that back-to-back link (iccp) not participate in RSTP then loop will happen right?

     

    Lets say i have two access switch. ASW-1 (two link) is LAG to Core  and ASW-2 (two link) is just RSTP to Core.

     

    https://www.juniper.net/documentation/en_US/junos/topics/topic-map/spanning-tree-configuring-rstp.html

     

    Thanks and appreciate your feedback



  • 4.  RE: Can MC-LAG & RSTP coexist at same time on QFX10k?

    Posted 08-27-2020 13:39

    kronicklez,

     

    Between the MC-LAG peers we'll have the ICCP protocol and the ICL link. You can have them both through the same physical link or in two different physical links.

     

    If you have the ICCP protocol over the ICL link, you don't need RSTP, because the ICL doesn't allow arp/mac learning, then a spanning tree protocol is not required because no loop will be formed. 

     

    In the other hand, if you have two Switches as downstream devices, it is recommended to enable RSTP in both MC-AEs and on the downstream device as well. 

    The MC-LAG peers should be the root bridge

     

    Regards,



  • 5.  RE: Can MC-LAG & RSTP coexist at same time on QFX10k?

    Posted 08-28-2020 08:47

    Hi rbabraham,

     

    yes, i'm use ICCP protocol using ICL link. So u means for example the ae0 (back-to-back trunk) dont need to assign under RSTP stanza?

     

    Do u have any other doc as reference coz it look like mandatory the back-to-back participate in RSTP as url given previously. Previously i have made loop using EX9200 due to forget the back-to-back interface participate in the RSTP .

     

    Thanks and appreciate any feedback



  • 6.  RE: Can MC-LAG & RSTP coexist at same time on QFX10k?
    Best Answer

    Posted 08-28-2020 14:38

    Hi 

     

    Correct the ICL doesn't need RSTP. Please check the following link with MC-LAG best practices

     

    • Configure STP globally so that STP can detect local miswiring within and across MC-LAG peers.

    • Disable STP on ICL links, however, because STP might block ICL interfaces and disable protection.

    https://www.juniper.net/documentation/en_US/junos/topics/concept/best-practices-usage-notes.html



  • 7.  RE: Can MC-LAG & RSTP coexist at same time on QFX10k?

    Posted 08-28-2020 21:47

    Hi rbabraham,

     

    I'm check on latest url that u given. Based on url below if my Spine/Core is using MX (currently i'm test using vMX version 18.4R2.7) it dont have command "set protocols rstp interface ae0 disable" . So how to make sure the ICL link not participate in RSTP if we cannot apply knob as highlated?

     

    https://www.juniper.net/documentation/en_US/junos/topics/topic-map/examples-mc-lag.html

     

    Thanks and appreciate your feedback



  • 8.  RE: Can MC-LAG & RSTP coexist at same time on QFX10k?

     
    Posted 08-28-2020 22:35

    You only specify the interfaces that do participate.

     

    set protocols rstp interface ae1
    set protocols rstp interface ae2
    set protocols rstp interface ae3
    set protocols rstp interface ae4
    set protocols rstp interface ae5
    ...


  • 9.  RE: Can MC-LAG & RSTP coexist at same time on QFX10k?

    Posted 08-29-2020 05:49

    Hi all,

     

    Thanks for all the input.