Routing

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  • 1.  I would like to know why BGP Neighbor is down.

    Posted 04-01-2022 10:21
    Reject policy was applied to import and export in a specific EBGP neighbor. . The configuration below is an example.

    #################################################

    set policy-options policy-statement REJECT_ALL then reject
    set protocols bgp group EBGP import REJECT_ALL
    set protocols bgp group EBGP export REJECT_ALL

    #################################################

    However, when I created another export policy as below and added it as an insert to the top of the REJECT_ALL policy of the bgp group, I saw that the BGP session was down for about 5 seconds and then reconnected. I wonder if it is originally down when an allow policy is added to the existing reject policy.

    Also, when two export policies are applied, is it correct to apply from the top export policy in top-down format? I was wondering how to evaluate 2 export policies.

    #################################################

    set policy-options policy-statement ADV_IPV6 term PREFIX from route-filter 1.1.1.1/24 exact
    set policy-options policy-statement ADV_IPV6 term PREFIX from route-filter 192.168.0.10/32 exact
    set policy-options policy-statement ADV_IPV6 term PREFIX then accept

    #################################################

    ------------------------------
    SEONGHO SHIN
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  • 2.  RE: I would like to know why BGP Neighbor is down.

     
    Posted 04-01-2022 20:20
    I have not lab tested this in a long time, but my previous experience with bgp changes is that as long as the group or bgp neighbor ip address stanza is not in the listed change when doing the pre change check, the peer does not bounce.

    After staging the change, but before the commit
    show | compare

    If the neighbor ip address stanza is shown in the deleted config session, the peer will bounce.
    Even if the same ip address appears below in the + config session.

    the compare process is showing what will be deleted and added for the config.  If the neighbor is deleted as part of the change the peer goes down.  And will come back up if it is part of the added config as well.

    ------------------------------
    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
    http://puluka.com/home
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