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Shamlink not establishing

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  • 1.  Shamlink not establishing

    Posted 11-07-2019 13:36

    Hej

    I am having a bit of problem with bringing Shamlink up on one of my PEs.

    I have a 4 PE setup interconnecting 3 customer sites.
    -->R3 and R4 are connected to the same Customer site
    -->R6
    -->R8

     

    The problem is at R4, which only establishes shamlink with R3 which it has connection through the same customer site. Whereas 3 establishes Shamlink with all Rs and R6/8 have shamlink with each other and R3

    All Rs have the R4's VRF loopback IP 172.30.5.21/32 in their route table learned through BGP. R4 routes are imported into each other R but routes

     

    Shamlink 1 = R4

    Oscar-Lab-R3# run show ospf neighbor instance CE1 
    Address Interface State ID Pri Dead
    192.168.0.70 ge-1/1/3.318 Full 172.31.63.2 128 33
    172.30.5.37 shamlink.0 Full 172.30.5.37 0 34
    172.30.5.21 shamlink.1 Full 172.30.5.21 0 33
    172.30.5.29 shamlink.2 Full 172.30.5.29 0 33
    Oscar-Lab-R4# run show ospf neighbor instance CE1 Address Interface State ID Pri Dead 192.168.0.74 ge-1/1/4.319 Full 172.31.63.3 128 34 172.30.5.17 shamlink.0 Full 172.30.5.17 0 34
    Oscar-Lab-R6# run show ospf neighbor instance CE1 Address Interface State ID Pri Dead 192.168.0.86 ge-1/1/6.322 Full 172.31.63.4 128 35 172.30.5.17 shamlink.0 Full 172.30.5.17 0 35 172.30.5.37 shamlink.2 Full 172.30.5.37 0 3 Oscar-Lab-R8# run show ospf neighbor instance CE1 Address Interface State ID Pri Dead 192.168.0.94 ge-1/1/8.324 Full 172.31.63.1 128 38 172.30.5.17 shamlink.0 Full 172.30.5.17 0 36 172.30.5.29 shamlink.2 Full 172.30.5.29 0 39

     

     

    {master}[edit routing-instances CE1 protocols ospf]
    odj@test3R1dk:Oscar-Lab-R4# show 
    export bgp-to-ospf;
    sham-link local 172.30.5.21;
    area 0.0.0.0 {
    sham-link-remote 172.30.5.17 metric 100; >>>>>>R3
    sham-link-remote 172.30.5.29; >>>>>>>>>>>>>>>>>>R6
    sham-link-remote 172.30.5.37; >>>>>>>>>>>>>>>>>>R8
    interface ge-1/1/4.319;
    interface lo0.141;
    }

     

     

    It looks like R4 is sending hello messages to all R3-6-8 but only absorbing R3 and local CE peer. The two messages peerat themselves. The IPs are R3, and Customer peer.

    Nov 7 22:21:33.971384 OSPF restart signaling: set L bit in hellos sent on interface shamlink.0.
    Nov 7 22:21:33.971412 OSPF sent Hello 172.30.5.21 -> 172.30.5.17 (shamlink.0 IFL 2147549184 area 0.0.0.0)
    Nov 7 22:21:33.971498 OSPF restart signaling: Add LLS data for Hello packet on interface shamlink.0.
    Nov 7 22:21:33.972321 OSPF restart signaling: set L bit in hellos sent on interface shamlink.1.
    Nov 7 22:21:33.972361 OSPF sent Hello 172.30.5.21 -> 172.30.5.29 (shamlink.1 IFL 2147549185 area 0.0.0.0)
    Nov 7 22:21:33.972448 OSPF restart signaling: Add LLS data for Hello packet on interface shamlink.1.
    Nov 7 22:21:33.972481 OSPF restart signaling: set L bit in hellos sent on interface shamlink.2.
    Nov 7 22:21:33.972510 OSPF sent Hello 172.30.5.21 -> 172.30.5.37 (shamlink.2 IFL 2147549186 area 0.0.0.0)
    Nov 7 22:21:33.973766 OSPF restart signaling: Add LLS data for Hello packet on interface shamlink.2.
    
    

     

    But it is only absorbing R3 and Local CE peer

    Nov  7 22:21:33.969965 OSPF hello from 172.30.5.17 (IFL 2684341140, area 0.0.0.0) absorbed
    Nov  7 22:21:33.970148 OSPF hello from 192.168.0.74 (IFL 2684341140, area 0.0.0.0) absorbed


    In contrast for example R6 absorbs hello from R3-6-8 and local CE peer

    Nov 7 22:22:51.194933 OSPF hello from 172.30.5.17 (IFL 2684341140, area 0.0.0.0) absorbed
    Nov 7 22:22:54.161435 OSPF hello from 192.168.0.86 (IFL 2684341140, area 0.0.0.0) absorbed
    Nov 7 22:22:55.239672 OSPF hello from 172.30.5.37 (IFL 2684341140, area 0.0.0.0) absorbed
    Nov 7 22:21:33.970148 OSPF hello from 192.168.0.74 (IFL 2684341140, area 0.0.0.0) absorbed

     

    Appreciate any advice
    Regards
    Oscar



  • 2.  RE: Shamlink not establishing

     
    Posted 11-08-2019 07:19

    If you disable R3 completely. Will R4 to R6 and R4 to R8 sham link come up?



  • 3.  RE: Shamlink not establishing

    Posted 11-08-2019 09:29

    Can you confirm R6 and R8 are sending hellos to R4? also you can try specifying a metric on R2 for the sham-links towards R6 and R8



  • 4.  RE: Shamlink not establishing

    Posted 11-09-2019 10:24

    Hej

    When I disable R3 the R4 still does not establish any shamlinks with R6 and R8

     

    When I check >show ospf route instance CE1 on R4 I do not see routes for Shamlink even from R3.

    However, on R3 I see routes from R4 shamlink

     

    R6 and R8 both send hello messages for the shamlink



  • 5.  RE: Shamlink not establishing

    Posted 11-11-2019 06:56

    As the configuration is not completely given here, I assume that the sham-link local and remote addresses are those of the VRF loopback interface, right? I also assume that the IP addresses of these loopback interfaces are announced via MP-BGP to the remote PE - just to rule out that you have a simple connectivity problem.

    If so, please remove the lo0.141-interface from the OSPF area 0 configuration stanca and just keep it in the VRF config.

    Cheers,

    Carsten



  • 6.  RE: Shamlink not establishing

     
    Posted 11-11-2019 08:20

    If you disbale R3, you are still seeing same behavior on R4, that means mostly issue on R4 config. And there's nothing related to dual-homing.

     

    Also you mentioned R6 and R8 sending hellos as expected. 

     

    I'd suggest to past config on R3 and R4 and check what's the difference



  • 7.  RE: Shamlink not establishing

    Posted 11-11-2019 23:57

    Hej

    Loo.141 is loopback specific to that VRF, main instance uses lo0.0. Each Router is configured the same way.

     

    The problem does indeed look like a routing problem.

    Even though each router have the VRF loopback address in their routing tables, R6 and R8 can not ping R4 VRF Loopback even when R3 is active/deactive

     

    {master}[edit]
    odj@test3pe1dk:Oscar-Lab-R3# run show route 172.30.5.0/24 table CE1.inet.0 | no-more 
    
    CE1.inet.0: 23 destinations, 44 routes (23 active, 0 holddown, 5 hidden)
    + = Active Route, - = Last Active, * = Both
    
    172.30.5.17/32     *[Direct/0] 10:37:10
                        > via lo0.131
    172.30.5.21/32     *[BGP/170] 10:37:29, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                        > to 172.30.0.22 via ge-1/1/3.134, Push 50
                          to 172.30.0.22 via ge-1/1/3.134, Push 50
    172.30.5.29/32     *[BGP/170] 10:38:20, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                        > to 172.30.0.22 via ge-1/1/3.134, label-switched-path Q
                          to 172.30.0.13 via ge-1/1/3.123, label-switched-path Bypass->172.30.0.22
    172.30.5.37/32     *[BGP/170] 10:38:20, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                        > to 172.30.0.13 via ge-1/1/3.123, label-switched-path J
                          to 172.30.0.22 via ge-1/1/3.134, label-switched-path L
                          to 172.30.0.22 via ge-1/1/3.134, label-switched-path Bypass->172.30.0.13->172.30.0.1
    odj@test3pe1dk:Oscar-Lab-R4# run show route 172.30.5.0/24 table CE1.inet.0 | no-more 
    
    CE1.inet.0: 28 destinations, 45 routes (28 active, 0 holddown, 0 hidden)
    + = Active Route, - = Last Active, * = Both
    
    172.30.5.17/32     *[BGP/170] 10:26:09, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                        > to 172.30.0.21 via ge-1/1/4.134, Push 54
                          to 172.30.0.21 via ge-1/1/4.134, Push 54
    172.30.5.21/32     *[Direct/0] 10:37:30
                        > via lo0.141
    172.30.5.29/32     *[BGP/170] 10:26:09, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                          to 172.30.0.21 via ge-1/1/4.134, Push 16
                        > to 172.30.0.30 via ge-1/1/4.145, Push 16
    172.30.5.37/32     *[BGP/170] 10:26:09, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                        > to 172.30.0.5 via ge-1/1/4.114, Push 16
                          to 172.30.0.30 via ge-1/1/4.145, Push 16
    odj@test3pe1dk:Oscar-Lab-R6# run show route 172.30.5.0/24 table CE1.inet.0 | no-more 
    
    CE1.inet.0: 27 destinations, 54 routes (23 active, 0 holddown, 16 hidden)
    + = Active Route, - = Last Active, * = Both
    
    172.30.5.17/32     *[BGP/170] 10:37:10, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                        > to 172.30.0.33 via ae1.156, label-switched-path R
                          to 172.30.0.25 via ge-1/1/6.136, label-switched-path Bypass->172.30.0.33
    172.30.5.21/32     *[BGP/170] 10:37:29, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                        > to 172.30.0.33 via ae1.156, Push 50
                          to 172.30.0.25 via ge-1/1/6.136, Push 50
    172.30.5.29/32     *[Direct/0] 11:15:18
                        > via lo0.161
    172.30.5.37/32     *[BGP/170] 11:12:03, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                        > to 172.30.0.33 via ae1.156, Push 16, Push 31(top)
                          to 172.30.0.33 via ae1.156, Push 16, Push 31(top)
                          to 172.30.0.42 via ge-1/1/6.167, Push 16, Push 24(top)
                          to 172.30.0.42 via ge-1/1/6.167, Push 16, Push 24(top)
    odj@test3pe1dk:Oscar-Lab-R8# run show route 172.30.5.0/24 table CE1.inet.0 | no-more 
    
    CE1.inet.0: 23 destinations, 50 routes (23 active, 0 holddown, 12 hidden)
    + = Active Route, - = Last Active, * = Both
    
    172.30.5.17/32     *[BGP/170] 10:37:10, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                        > to 172.30.0.9 via ge-1/1/8.118, label-switched-path I
                          to 172.30.0.45 via ge-1/1/8.178, label-switched-path K
                          to 172.30.0.45 via ge-1/1/8.178, label-switched-path Bypass->172.30.0.9->172.30.0.2
    172.30.5.21/32     *[BGP/170] 10:37:29, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                        > to 172.30.0.9 via ge-1/1/8.118, Push 50
                          to 172.30.0.37 via ge-1/1/8.158, Push 50
    172.30.5.29/32     *[BGP/170] 11:12:03, localpref 100, from 172.30.5.41
                          AS path: I, validation-state: unverified
                          to 172.30.0.37 via ge-1/1/8.158, Push 16, Push 29(top)
                          to 172.30.0.37 via ge-1/1/8.158, Push 16, Push 29(top)
                        > to 172.30.0.45 via ge-1/1/8.178, Push 16, Push 25(top)
                          to 172.30.0.45 via ge-1/1/8.178, Push 16, Push 25(top)
    172.30.5.37/32     *[Direct/0] 11:15:18
                        > via lo0.181


    Regards

    Oscar



  • 8.  RE: Shamlink not establishing

    Posted 11-13-2019 01:35

    Yes, it looks like a routing problem. But with the limited output you provided, it is really hard to debug. Especially as you seem to use a mix of LDP- and RSVP-based LSPs. In addition, output indicates that there is a route reflector (172.30.5.41) involved as well which was not mentioned. Would be really beneficial to see the configs of all system.

    Cheers,

    Carsten



  • 9.  RE: Shamlink not establishing
    Best Answer

     
    Posted 11-13-2019 07:33

    The output is really limited. Maybe you should try to create RSVP LSP from R4 to R3/R6/R8



  • 10.  RE: Shamlink not establishing

    Posted 11-13-2019 13:21

    @Mhu: Setting RSVP with R6 and R8 brought up the Shamlink.

     

    Although still not sure on the reason.  I can ping both R6 and R8 normal loopbacks through IGP and all VRF loopbacks were advertised within the VRFs before LSP.

    I can provide full config on the devices but there is alot of stuff going on in the config since I lab lots of different stuff at it.