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Line rate capacity dependency on SCB

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  • 1.  Line rate capacity dependency on SCB

    Posted 25 days ago
    If I have 3 CB slots available on my MX device and I install all 3 of them how will that affect the rate capacity on line card installed. Do I really need 3 SCBs in place?


  • 2.  Re: Line rate capacity dependency on SCB

    Posted 25 days ago

    Two SCB are capable to handle the full capacity of lin cards, third SCB is for redundancy purpose, if any of the first two SCBs goes down, then the third standby will take over.




  • 3.  Re: Line rate capacity dependency on SCB
    Best Answer

    Posted 25 days ago

    Hi Reload,

     

    There is a solved query regarding this on our forum :

     

    "Redundancy in Fabric depends on mode at which SCBE3-MX cards are operating at, there are 2 modes [increased-bandwidth | redundant] and this is configurable 

    https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/redundanc...

     

     - MX960 can have up to 3 SCB cards, in redundant mode 2 fabric cards are active and 1 card is standby, while in non-redundant mode / increased-bandwidth all 3 SCB cards are active.

    - when all 3 SCB cards are active you get 1.5 Tbps fabric capacity per slot and when only 2 cards are active you get 1Tbps fabric capacity per slot and this is the default mode for SCB3-MX"

     

    Query link:

    https://forums.juniper.net/t5/Junos/Question-about-SCBE3-MX/td-p/480680

     

    For details about SCB: https://www.juniper.net/documentation/en_US/release-independent/junos/topics/concept/SCB-description.html

     

    No, it is not mandatory to have 3 SCBs installed. Your MX device will work just fine with two. The third one is for redundancy purposes. ( standby )

     

    HTH

     

    Mark "Accept As Solution" in case this helps.

     

     



  • 4.  Re: Line rate capacity dependency on SCB

    Posted 25 days ago
    This means my third SCB is for worst situation case. One a 2 RE device. I think if 2 SCBs are fine, third one won't even be needed until one of the SCBs cause issue.


  • 5.  Re: Line rate capacity dependency on SCB

    Posted 25 days ago

    Yes, the third SCB is to maintain 2+1 redundancy. Which comes into play when there is an issue with one of the active ( primary and backup ) SCBs.