Dumb question about bgp network command

Sample topology:

SP-PE1 <---ebgp--->CE2  (part of more complex topology MPLS CSC)

SP-PE1:

interface Ethernet0/0

 ip vrf forwarding CE1

 ip address 117.8.20.1 255.255.255.252

end


SP-PE1#sh ip vrf

  Name                             Default RD            Interfaces

  CE1                              32050:100             Et0/0


router bgp 32050

 bgp log-neighbor-changes

 neighbor 10.0.252.4 remote-as 32050

 neighbor 10.0.252.4 update-source Loopback0

 !

 address-family vpnv4

  neighbor 10.0.252.4 activate

  neighbor 10.0.252.4 send-community extended

 exit-address-family

 !

 address-family ipv4 vrf CE1

  network 33.33.33.33 mask 255.255.255.255

  neighbor 117.8.20.2 remote-as 12048

  neighbor 117.8.20.2 activate

  neighbor 117.8.20.2 soft-reconfiguration inbound

 exit-address-family

 

SP-PE1#sh ip route vrf CE1


Gateway of last resort is not set


      22.0.0.0/32 is subnetted, 1 subnets

B        22.22.22.22 [20/0] via 117.8.20.2, 00:30:04

      33.0.0.0/32 is subnetted, 1 subnets

B        33.33.33.33 [200/0] via 10.0.253.1, 00:30:04

      117.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        117.8.20.0/30 is directly connected, Ethernet0/0

L        117.8.20.1/32 is directly connected, Ethernet0/0




CE1:



CE1#sh ip route




Gateway of last resort is not set


      22.0.0.0/32 is subnetted, 1 subnets

C        22.22.22.22 is directly connected, Loopback0

      117.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

C        117.8.20.0/30 is directly connected, Ethernet0/0

L        117.8.20.2/32 is directly connected, Ethernet0/0




CE1#sh run | sec bgp

router bgp 12048

 bgp log-neighbor-changes

 network 22.22.22.22 mask 255.255.255.255

 neighbor 117.8.20.1 remote-as 32050

 neighbor 117.8.20.1 soft-reconfiguration inbound




Question:

Why CE1 did not recieve 33.33.33.33/32 route ? (this route is in SP-PE1 vrf route table and in 'network' command)


Comments

  • peetypeety ✭✭✭

    You're chasing the wrong thing here. In your SP-PE1# sh ip route vrf CE1 output, you can already see 33.33.33.33/32 as a BGP route. That means that it's being learned from somewhere else over BGP inside that VRF (either another CE hung off this PE, or from a different PE). The network statement is meaningless in this context - the network command allows a non-BGP route to be originated into BGP, but that's not what you have here.

    You probably need to do "sh ip bgp vrf CE1 33.33.33.33/32" and look at the attributes to see why it didn't get propagated to CE1. It's a BGP propagation problem, not a BGP origination problem.

  • On PE1, can you verify that it advertises 33.33.33.33/32, and
    On CE1, can you verify that it receives 33.33.33./32?

    Regards,
    David Sudjiman

    On Sat, Oct 8, 2016 at 4:23 AM, SDS80 <[email protected]> wrote:

    Sample topology:

    SP-PE1 <---ebgp--->CE2  (part of more complex topology MPLS CSC)

    SP-PE1:

    interface Ethernet0/0

     ip vrf forwarding CE1

     ip address 117.8.20.1 255.255.255.252

    end


    SP-PE1#sh ip vrf

      Name                             Default RD            Interfaces

      CE1                              32050:100             Et0/0


    router bgp 32050

     bgp log-neighbor-changes

     neighbor 10.0.252.4 remote-as 32050

     neighbor 10.0.252.4 update-source Loopback0

     !

     address-family vpnv4

      neighbor 10.0.252.4 activate

      neighbor 10.0.252.4 send-community extended

     exit-address-family

     !

     address-family ipv4 vrf CE1

      network 33.33.33.33 mask 255.255.255.255

      neighbor 117.8.20.2 remote-as 12048

      neighbor 117.8.20.2 activate

      neighbor 117.8.20.2 soft-reconfiguration inbound

     exit-address-family

     

    SP-PE1#sh ip route vrf CE1


    Gateway of last resort is not set


          22.0.0.0/32 is subnetted, 1 subnets

    B        22.22.22.22 [20/0] via 117.8.20.2, 00:30:04

          33.0.0.0/32 is subnetted, 1 subnets

    B        33.33.33.33 [200/0] via 10.0.253.1, 00:30:04

          117.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

    C        117.8.20.0/30 is directly connected, Ethernet0/0

    L        117.8.20.1/32 is directly connected, Ethernet0/0




    CE1:



    CE1#sh ip route




    Gateway of last resort is not set


          22.0.0.0/32 is subnetted, 1 subnets

    C        22.22.22.22 is directly connected, Loopback0

          117.0.0.0/8 is variably subnetted, 2 subnets, 2 masks

    C        117.8.20.0/30 is directly connected, Ethernet0/0

    L        117.8.20.2/32 is directly connected, Ethernet0/0




    CE1#sh run | sec bgp

    router bgp 12048

     bgp log-neighbor-changes

     network 22.22.22.22 mask 255.255.255.255

     neighbor 117.8.20.1 remote-as 32050

     neighbor 117.8.20.1 soft-reconfiguration inbound




    Question:

    Why CE1 did not recieve 33.33.33.33/32 route ? (this route is in SP-PE1 vrf route table and in 'network' command)





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  • i don't have such command :

    SP-PE1#sh ip bgp vrf?


    % Unrecognized command




    SP-PE1#sh ip bgp vpnv4 vrf CE1

    BGP table version is 4, local router ID is 10.0.252.1

    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

                  r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,

                  x best-external, a additional-path, c RIB-compressed,

    Origin codes: i - IGP, e - EGP, ? - incomplete

    RPKI validation codes: V valid, I invalid, N Not found


         Network          Next Hop            Metric LocPrf Weight Path

    Route Distinguisher: 32050:100 (default for vrf CE1)

     *>  22.22.22.22/32   117.8.20.2               0             0 12048 i

     *>i 33.33.33.33/32   10.0.253.1               0    100      0 12048 i




    SP-PE1#sh ip bgp vpnv4 vrf CE1 33.33.33.33/32

    BGP routing table entry for 32050:100:33.33.33.33/32, version 4

    Paths: (1 available, best #1, table CE1)

      Advertised to update-groups:

         1

      Refresh Epoch 1

      12048

        10.0.253.1 (metric 1) from 10.0.252.4 (10.0.252.4)

          Origin IGP, metric 0, localpref 100, valid, internal, best

          Extended Community: RT:32050:100

          Originator: 10.0.253.1, Cluster list: 10.0.252.4, 10.0.253.4

          mpls labels in/out nolabel/23

          rx pathid: 0, tx pathid: 0x0


  • PE1 advertised but CE1 not received:

    SP-PE1#sh ip bgp vpnv4 vrf CE1 neighbors 117.8.20.2 advertised-routes

    BGP table version is 4, local router ID is 10.0.252.1

    Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,

                  r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,

                  x best-external, a additional-path, c RIB-compressed,

    Origin codes: i - IGP, e - EGP, ? - incomplete

    RPKI validation codes: V valid, I invalid, N Not found

     

         Network          Next Hop            Metric LocPrf Weight Path

    Route Distinguisher: 32050:100 (default for vrf CE1)

     *>i 33.33.33.33/32   10.0.253.1               0    100      0 12048 i

     

    Total number of prefixes 1



    CE1#sh ip bgp neighbors 117.8.20.1 received-routes


    Total number of prefixes 0


  • peetypeety ✭✭✭

    I'm rusty on some of this, but here's a brain spew of ideas: do you need allowas-in on the CE? Do you need to send and receive a route to cover the next-hop, so the route in question doesn't get dropped due to no next hop reachability?

  • Thanks! There is missing option "allowas-in" on CE routers.

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