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MC-lag question

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  • 1.  MC-lag question

    Posted 08-11-2018 00:39

    hey Junos


    hey rccpgm


    im following this pdf to make the MC-LAG configuration but there is something i didnt get



    in the page 33

    set protocols iccp peer backup-liveness-detection backup-peer-ip


    the ip is it point to point FXP0 ip or what? and should i advirtise it by ospf


    2nd question


    set interfaces irb unit 100 family inet address arp mac 00:1f:12:b6:6f:f0


    what command to show me that needed mac, show int irb.100 ex?


    thanks in advance

  • 2.  RE: MC-lag question
    Best Answer

    Posted 08-11-2018 06:09

    Backup-liveness-connection is optional and has always confused me as well.  Unfortunately, the documentation is clear as mud on this subject.  See here (FYI if you select the CLI Explorer re-direct, you'll just end up in a loop!):




    Basically as far as I know it is just a second connection between the nodes other than ICCP/ICL to test if other node is up or not.  Therefore additional protection if ICCP goes down.  A better solution, IMHO, is to put in additional redundancy for ICCP/ICP.  I always recommend these be put together as part of an AE that is split HW wise across different modules.  Requires at least 2 faults to physically have this link go down.


    Yes, FXP0 can be used for this - most common method??   I think so.  As for learning within OSPF, I'd think no.  Just need communication across this link between the 2 nodes.


    As for interface mac, I'd suggest you use either:


    show interface extensive (look for hardware address)


    show interface ge-x/y/z extensive | match hardware


    This should work for both physical and logical interfaces


    Just FYI for anyone reading this article, Juniper is moving away from MC-LAG as one the preferred solution, to instead use EVPN/VXLAN (or MPLS depending upon product) almost exclusively.  If you have a greenfield deployment, I might suggest it is a good idea to consider an EVPN based architecture, or at least consider this technology.


    Good luck, HTH.

  • 3.  RE: MC-lag question

    Posted 08-23-2018 02:56

    is it the same MAC that showing when doing the command


    show lldp neighbors?

  • 4.  RE: MC-lag question

    Posted 08-23-2018 05:28

    I believe yes, maybe someone else could confirm 100%.

  • 5.  RE: MC-lag question

    Posted 08-26-2018 06:37



    dose this worning looks familiar to you


    "warning: prefer-status-control-active is used with status-control standby. Use this command only if BLD is configured"


    its showing while commiting i didnt do the backup-liveness-detection since you mentioned its optional.