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How to confirm with advertising successfully or not via BGP

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  • 1.  How to confirm with advertising successfully or not via BGP

    Posted 01-26-2018 00:19
      |   view attached

    Hello

     

    I create one router with one logical system "Test" for iBGP neighbor. iBGP is established successfully. And logical system "Test" also got routes.

     

    Then I advertised a static route with community 999:10000 that will be received by logical system Test.

    If I add more one community777:20131 that should prepend one time, but logical system wasn't received it.

     

    I confirmed that route is advertised to logical system "Test", but can't show this route in logical system "Test. even use show routes logical system Test hidden.

     

    How do I to find what policy make the route failed ? Is there any command for checking ?

     

    RE0> show bgp summary

    192.168.144.8 64050 11705 11737 0 0 3d 3:57:02 Establ
    inet.0: 0/153/4/0
    inet.2: 0/0/0/0
    inetflow.0: 0/0/0/0
    bgp.l3vpn.0: 0/0/0/0
    bgp.l2vpn.0: 0/0/0/0
    bgp.evpn.0: 0/0/0/0

     

    RE0> show route logical-system Test receive-protocol bgp 103.198.144.6

    Prefix Nexthop MED Lclpref AS path

    10.3.0.2/32 103.198.144.41 10 100 I

    10.3.0.3/32 103.198.144.41 11 100 I

    10.3.0.6/32 103.198.144.41 11 100 I

    10.3.0.8/32 103.198.144.41 12 100 I

    10.3.0.10/32 103.198.144.41 11 100 I

    10.3.0.11/32 103.198.144.41 11 100 I

    Omitted

     

    RE0>show route advertising-protocol bgp 192.168.144.8 27.50.63.0/25 detail

    inet.0: 163 destinations, 317 routes (163 active, 1 holddown, 149 hidden)
    * 27.50.63.0/25 (1 entry, 1 announced)
    BGP group IBGP_v4 type Internal
    Nexthop: Self
    Localpref: 100
    AS path: 64050 [64050] I
    Communities: 999:10000 777:20131

     

    RE0>show route all logical-system Test receive-protocol bgp 192.168.144.6 | match /25

    (nothing)


    #IBGP

    Attachment(s)

    rtf
    BGP policy.rtf   2K 1 version


  • 2.  RE: How to confirm with advertising successfully or not via BGP

    Posted 01-26-2018 00:35
    Can you draw a rough topology of your connectivity and share the bgp config from both box?


  • 3.  RE: How to confirm with advertising successfully or not via BGP

    Posted 01-26-2018 00:58

    Hello

     

    I had attached the configuration , and this diagram is the infrastructure.

    Thanks.螢幕快照 2018-01-26 下午4.55.43.png

     

    Best regards,

    Cloud



  • 4.  RE: How to confirm with advertising successfully or not via BGP

    Posted 01-26-2018 01:25
    Can you please share this policy-config as well? Or it would be great if you can share the complete config of your box


    BH-IN IBGP-FROM-MAIN ACCEPT-ALL

    Regards
    Harpreet


  • 5.  RE: How to confirm with advertising successfully or not via BGP

    Posted 01-29-2018 12:43

    Hi,

     

    Please provide output of below command along with your policy config, it will help to identify the reason of route being hidden/not accepted.

     

    >show route all logical-system Test receive-protocol bgp 192.168.144.6 hidden extensive

     

    //BR

    AD



  • 6.  RE: How to confirm with advertising successfully or not via BGP
    Best Answer

    Posted 01-29-2018 13:42

    Hello there,

     

     


    I create one router with one logical system "Test" for iBGP neighbor. iBGP is established successfully.

     

    <skip>

     

    RE0> show bgp summary

    192.168.144.8 64050 11705 11737 0 0 3d 3:57:02 Establ
    inet.0: 0/153/4/0


     

     

    Ok, so 64050 is Your iBGP ASN then.

     


     

    RE0>show route advertising-protocol bgp 192.168.144.8 27.50.63.0/25 detail

    inet.0: 163 destinations, 317 routes (163 active, 1 holddown, 149 hidden)
    * 27.50.63.0/25 (1 entry, 1 announced)
    BGP group IBGP_v4 type Internal
    Nexthop: Self
    Localpref: 100
    AS path: 64050 [64050] I
    Communities: 999:10000 777:20131

     

     


    So, You advertise a route with iBGP ASN in the AS_PATH to Your IBGP neighbor.

    Bad idea, I am afraid - by default this route will be rejected  by 192.168.144.8 due to "AS_PATH loop" and it won't even show as hidden. 

    You need to allow AS_PATH loops in the config on 192.168.144.8 side, or prepend some other ASN if You absolutely need to make the AS_PATH artificially longer.

    To allow AS_PATH loops in the configuration, check out this link 

    https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/loops-edit-protocols-bgp-family.html

    HTH

    Thx
    Alex