Routing

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  • 1.  BGP issue & BGP communities

    Posted 17 days ago
    Hi, 
    I currently studdy BGP & BGP communites using Juniper V-Lab topology.  I decide to use topologie named "OSPF - Multi-area".  All router been erased and load withj the attached configuration to this post.
    I know actually that I have multiple issue in my including AS65000 & AS65002 to be transit AS.  Where they considered as custome AS.  Routers on the top VMX1 & VMX conside ISP-1 in AS65001.  Router on the bottom VMX3 & VMX4 are ISP-2 in AS65003.
    AS65002 advertise 10.30.0.0/24, 10.31.0/24 & 10.32.0/24 To both ISPs with communities 65001:110 and 65003:90.  I'like to use these communites to set the local pref to 110 and 90 respectively, to make ISP-1 be prefered.
    But ISP-1 does'nt install route in the routing table because the the next-hop is condired unsuable, but I don't know why.
    Today to make toplogy simplest I only put back configuration to vMX2, vMX4 & vMX6.  To have less implicated and less router as well.  If I disable path between vMX2 & vMX4 route to AS65002 are completely removed from the vMX2 FIB since path over ge-0/0/3 is considered unusabled.
    vMX2 routing table :
    jcluser@vMX2# run show route                        
    inet.0: 17 destinations, 22 routes (17 active, 0 holddown, 5 hidden)
    + = Active Route, - = Last Active, * = Both
    0.0.0.0/0          *[Static/5] 00:38:25
                        >  to 100.123.0.1 via fxp0.0
    10.2.2.2/32        *[Direct/0] 00:38:25
                        >  via lo0.0
    10.30.0.0/24       *[BGP/170] 00:02:26, localpref 100
                          AS path: 65003 65002 I, validation-state: unverified
                        >  to 10.150.6.254 via ge-0/0/2.0
    10.31.0.0/24       *[BGP/170] 00:02:26, localpref 100
                          AS path: 65003 65002 I, validation-state: unverified
                        >  to 10.150.6.254 via ge-0/0/2.0
    10.32.0.0/24       *[BGP/170] 00:02:26, localpref 100
                          AS path: 65003 65002 I, validation-state: unverified
                        >  to 10.150.6.254 via ge-0/0/2.0
    10.150.1.0/24      *[Direct/0] 00:37:58
                        >  via ge-0/0/0.0
    10.150.1.2/32      *[Local/0] 00:37:58
                           Local via ge-0/0/0.0
    10.150.4.0/24      *[Direct/0] 00:37:58
                        >  via ge-0/0/1.0
    10.150.4.2/32      *[Local/0] 00:37:58
                           Local via ge-0/0/1.0
    10.150.6.0/24      *[Direct/0] 00:02:28
                        >  via ge-0/0/2.0
    10.150.6.2/32      *[Local/0] 00:02:28
                           Local via ge-0/0/2.0
    10.200.1.0/25      *[Direct/0] 00:37:58
                        >  via ge-0/0/3.0
    10.200.1.2/32      *[Local/0] 00:37:58
                           Local via ge-0/0/3.0
    10.200.1.128/25    *[BGP/170] 00:02:26, localpref 100
                          AS path: 65003 65002 I, validation-state: unverified
                        >  to 10.150.6.254 via ge-0/0/2.0
    100.123.0.0/16     *[Direct/0] 00:38:25
                        >  via fxp0.0
    100.123.1.1/32     *[Local/0] 00:38:25
                           Local via fxp0.0
    224.0.0.5/32       *[OSPF/10] 00:38:25, metric 1
                           MultiRecv
    inet6.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
    + = Active Route, - = Last Active, * = Both
    ff02::2/128        *[INET6/0] 00:38:25
                           MultiRecv
    [edit]
    jcluser@vMX2# 
    jcluser@vMX2# run show route 10.30.0.0/24 all extensive    
    inet.0: 17 destinations, 22 routes (17 active, 0 holddown, 5 hidden)
    10.30.0.0/24 (2 entries, 1 announced)
    TSI:
    KRT in-kernel 10.30.0.0/24 -> {10.150.6.254}
    Page 0 idx 1, (group gr-AS65002 type External) Type 1 val 0xd69d644 (adv_entry)
       Advertised metrics:
         Nexthop: Self
         AS path: [65001] 65003 65002 I
         Communities: 65003:90
        Advertise: 00000001
    Path 10.30.0.0
    from 10.150.6.254
    Vector len 4.  Val: 1
            *BGP    Preference: 170/-101
                    Next hop type: Router, Next hop index: 595
                    Address: 0xc4b5ae4
                    Next-hop reference count: 8
                    Source: 10.150.6.254
                    Next hop: 10.150.6.254 via ge-0/0/2.0, selected
                    Session Id: 0x140
                    State: <Active Ext>
                    Local AS: 65001 Peer AS: 65003
                    Age: 3:38 
                    Validation State: unverified 
                    Task: BGP_65003.10.150.6.254
                    Announcement bits (2): 0-KRT 4-BGP_RT_Background 
                    AS path: 65003 65002 I 
                    Communities: 65003:90
                    Accepted
                    Localpref: 100
                    Router ID: 10.4.4.4
                    Thread: junos-main 
             BGP    Preference: 170/-111
                    Next hop type: Unusable, Next hop index: 0
                    Address: 0xc4b50bc
                    Next-hop reference count: 5
                    Source: 10.200.1.1
                    State: <Hidden Ext>
                    Inactive reason: Unusable path
                    Local AS: 65001 Peer AS: 65002
                    Age: 39:00 
                    Validation State: unverified 
                    Task: BGP_65002.10.200.1.1
                    AS path: 65002 I 
                    Communities: 65001:110
                    Accepted
                    Localpref: 110
        Router ID: 10.6.6.6
                    Thread: junos-main 
    [edit]
    jcluser@vMX2# 
    Anyone can help me ?



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    Xine
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    Attachment(s)

    txt
    vmx4.txt   4 KB 1 version
    pdf
    OSPF - Multi-area.pdf   59 KB 1 version
    txt
    vmx1.txt   5 KB 1 version
    txt
    vmx5.txt   2 KB 1 version
    txt
    vmx3.txt   4 KB 1 version
    txt
    VMX6.txt   3 KB 1 version
    txt
    vmx2.txt   4 KB 1 version


  • 2.  RE: BGP issue & BGP communities

    Posted 16 days ago

    You have configured «then next-hop self» in an IMPORT policy (pol-FROMCUST), this is nonsense. vMX2 won't accept a route with a next-hop modified to be equal to itself.

    nexthop self is only set in export policies.



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    Olivier Benghozi
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