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BGP Communities

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  • 1.  BGP Communities

    Posted 11-29-2014 14:06

    Hi All,

     

    I'd like to create a BGP community that matches 3 different members:

     

    777

    1777

    2777

     

    Using the "." I'm able to successfully match 1777 and 2777, but the 777 is disregarded. Expected. 

     

    Adding a 2nd member to the same community list breaks the community-list , i.e.

     

    community match-test members asn:.777 asn:777 or a 

    community match-test members "asn:[1-2]777" asn:777

     

    Any ideas what the magic regular expression is?

     

    Kind regards,

     

    Andrew 

     


    #BGPCommunities


  • 2.  RE: BGP Communities
    Best Answer

     
    Posted 11-29-2014 18:36

    Try the following:

     

    (1|2){0,1}777



  • 3.  RE: BGP Communities

    Posted 11-30-2014 03:20

    Perfect!  Thank you



  • 4.  RE: BGP Communities

    Posted 08-03-2017 13:05

    Hi friends!

     

    I need to match 2 communities on the same prefix in an import BGP policy to forward determinate traffic type. How can I proceed it? Just creating 2 terms (one for each community), because policy performs "OR" operation inside term, correct? I could use a "next-policy" statement  too... There are any other "more useful" proceed to do it?  Thanks.

     

     



  • 5.  RE: BGP Communities

    Posted 08-03-2017 13:15

    For example, if prefixe has both communities 65000:10 and 65000:20, then it matches the policy. If prefixe have only community 65000:10 or other, so it no match this policy.



  • 6.  RE: BGP Communities

     
    Posted 08-04-2017 05:22

    You are correct, because the community attribute in a term is a logical or, you will need to have two terms to successfully check for routes with both community set.

     

    I would do this as the final check in the policy

     

    The first term will check for 65000:10 and if present proceed to the next term.

    If not present proceed to the the final policy in your chain or end

     

    The second term checks for 65000:20 and if present does the desired action

    If not proceed to the final policy in the chain or end