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An NE40E Fails to Advertise the Imported Default Routes to Other Peers Through BGP

Publication Date:  2019-04-07 Views:  152 Downloads:  0

Issue Description

Device model: NE40E-X16A

Device version: V800R008

Topology: S12700------NE1---------NE2

Symptom: OSPF runs between S12700 and NE1, and IBGP runs between NE1 and NE2. S12700 is configured with default-route-advertise to advertise default routes to NE1 through OSPF. NE1 then advertises the default routes to NE2.

 

NE1 can learn the default routes advertised from S12700, but NE2 fails to do that.

 

Handling Process

1. Check routing tables of all the devices. It is found that NE-1 has learned default routes but NE-2 has not.

S12700 routing table:

 

<S12708_CSS>            dis ip routing-table vpn-instance Internet-vpn

Route Flags: R - relay, D - download to fib

------------------------------------------------------------------------------

Routing Tables: Internet-vpn

         Destinations : 175      Routes : 175      

 

Destination/Mask    Proto   Pre  Cost      Flags NextHop         Interface

 

        0.0.0.0/0   Static  60   0          RD   10.10.0.46      XGigabitEthernet1/1/0/1

 

NE40-1 routing table:

 

<NE40-1>dis ip routing-table vpn-instance Internet-vpn 

Route Flags: R - relay, D - download to fib, T - to vpn-instance, B - black hole route

------------------------------------------------------------------------------

Routing Table : Internet-vpn

         Destinations : 153      Routes : 153       

 

Destination/Mask    Proto   Pre  Cost        Flags NextHop         Interface

 

        0.0.0.0/0   O_ASE   150  1             D   10.9.6.2        Eth-Trunk2.4

 

NE40-2 routing table:

 

<NE40-2>dis ip routing-table vpn-instance Internet-vpn 

Route Flags: R - relay, D - download to fib, T - to vpn-instance, B - black hole route

------------------------------------------------------------------------------

Routing Table : Internet-vpn

         Destinations : 136      Routes : 136       

 

Destination/Mask    Proto   Pre  Cost        Flags NextHop         Interface

 

       10.9.6.0/30  IBGP    255  2             RD  10.9.0.1        GigabitEthernet1/0/0

      10.9.6.16/30  Direct  0    0             D   10.9.6.17       GigabitEthernet2/0/4.4

      10.9.6.17/32  Direct  0    0             D   127.0.0.1       GigabitEthernet2/0/4.4

      10.9.6.19/32  Direct  0    0             D   127.0.0.1       GigabitEthernet2/0/4.4

      10.9.6.20/30  IBGP    255  2             RD  10.9.0.4        GigabitEthernet2/0/0

 

2. Check the route advertisement configuration on NE-1. It is found that default-route imported is configured for ipv4-family unicast.

ipv4-family unicast

  undo synchronization

  default-route imported

  import-route ospf 1

  peer 10.9.0.3 default-route-advertise

Root Cause

The default routes of Internet-vpn should be advertised, but default-route imported is configured for ipv4-family unicast. Therefore, the default routes of a VPN are not advertised.

Solution

Configure default-route imported in the ipv4-family vpn-instance Internet-vpn view. If default VPN routes are learned through OSPF, use the import-route configuration. If default VPN routes of Internet-vpn are learned, use the peer default-originate vpn-instance configuration.

Suggestions

With the default-route imported configuration, default VPN routes in the local routing table can be advertised. However, this configuration must be performed in the ipv4-family vpn-instance view.

END