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dal Participant
Participant

Routes learned from BGP are not distributed into OSPF

Hi.

I have a problem I'm not able to solve:
I have some routes learned from BGP that I need to redistribute into OSPF.
But I just cant get the hang of it.

Here is output from Router 1:

C6509#sh ip route vrf VRF_Name bgp 65200


Gateway of last resort is 10.0.0.1 to network 0.0.0.0

B*    0.0.0.0/0 [200/0] via 10.0.0.1, 00:09:28
      10.0.0.0/8 is variably subnetted, 20 subnets, 4 masks
B        10.50.1.0/24 [200/0] via 10.0.0.1, 00:09:28
B        10.50.255.0/28 [200/0] via 10.0.0.1, 00:09:28

As you can see, the router has learned a few routes from BGP.

Here is the config:

router ospf 50 vrf VRF_Name
 router-id 10.50.12.1
 redistribute bgp 65200 subnets
 
router bgp 65200
 bgp router-id 10.0.0.12
 bgp log-neighbor-changes
 neighbor 10.0.0.1 remote-as 65200
 neighbor 10.0.0.1 update-source Loopback0
 !
 address-family ipv4
  redistribute connected
  redistribute static
  neighbor 10.0.0.1 activate
  neighbor 10.0.0.1 soft-reconfiguration inbound
 exit-address-family
 !
 address-family vpnv4
  neighbor 10.0.0.1 activate
  neighbor 10.0.0.1 send-community extended
 exit-address-family
 !
 address-family ipv4 vrf VRF_Name
  no bgp redistribute-internal
  redistribute connected
  redistribute static
  redistribute ospf 50 metric 2
 exit-address-family
 
C6509#show ip protocols vrf VRF_Name

Routing Protocol is "bgp 65200"
  Outgoing update filter list for all interfaces is not set
  Incoming update filter list for all interfaces is not set
  IGP synchronization is disabled
  Automatic route summarization is disabled
  Redistributing: connected, ospf 50 (internal)
                  
  Maximum path: 1
  Routing Information Sources:
    Gateway         Distance      Last Update
  Distance: external 20 internal 200 local 200

Routing Protocol is "ospf 50"
  Outgoing update filter list for all interfaces is not set
  Incoming update filter list for all interfaces is not set
  Router ID 10.50.12.1
  It is an area border and autonomous system boundary router
 Redistributing External Routes from,
    bgp 65200, includes subnets in redistribution
  Number of areas in this router is 1. 1 normal 0 stub 0 nssa
  Maximum path: 4
  Routing for Networks:
  Routing on Interfaces Configured Explicitly (Area 0):
    Vlan328
    Vlan964
    Vlan967
    Vlan968
    Vlan969
    Vlan312
  Routing Information Sources:
    Gateway         Distance      Last Update
    10.50.11.1           110      00:38:53
    10.50.13.1           110      00:38:48
    10.50.15.1           110      00:38:48
    10.50.14.1           110      00:38:48
    10.50.1.1            110      2d09h
  Distance: (default is 110)
 
 As you can see, OSPF *should* redistribute routes from BPG
 But the output from the next router shows no sign of the routes listed earlier in this post.
All other routes that comes from OSPF only shows in the routing table without problems.
 Any ideas why not?

Thanks.

5 REPLIES 5
Highlighted
VIP Advisor

check this post:

check this post:

https://supportforums.cisco.com/discussion/11178396/ospf-routing-bit-lsa

Please remember to rate useful posts, by clicking on the stars below.

Highlighted
Cisco Employee

Hello, 

Hello, 

The detail in your setup is that your BGP routes are internal. 

C6509#sh ip route vrf VRF_Name bgp 65200


Gateway of last resort is 10.0.0.1 to network 0.0.0.0

B*    0.0.0.0/0 [200/0] via 10.0.0.1, 00:09:28
      10.0.0.0/8 is variably subnetted, 20 subnets, 4 masks
B        10.50.1.0/24 [200/0] via 10.0.0.1, 00:09:28
B        10.50.255.0/28 [200/0] via 10.0.0.1, 00:09:28

You can see that the AD is equal to 200, and BGP does not redistribute internal Routes as could be dangerous for loops. 

To be able to redistribute internal BGP routes please enable the following command under the address family VRF on BGP process:

IOU2(config-router-af)#bgp redistribute-internal

After this command, you should be able to see it at the other end. 

IOU1#sh ip route ospf | b of
Gateway of last resort is not set

     10.0.0.0/32 is subnetted, 1 subnets
O E2     10.10.10.10 [110/1] via 12.12.12.2, 00:02:35, Ethernet0/0

Hope this help to solve your problem.

Regards!

Highlighted
dal Participant
Participant

Hi.Thank you for your answers

Hi.
Thank you for your answers.

A combination of both your replies took me one step further.

When enabling bgp redistribute-internal together with the command capability vrf-lite, I am now seeing two more routes in the routing table:

O E2     10.50.1.0/24 [110/1] via 10.50.255.113, 01:27:54, Vlan966
O E2     10.50.255.0/28 [110/1] via 10.50.255.113, 01:27:54, Vlan966

But the default route is still a no show.
I wonder why?

Since those 2 commands are disabled by default, I guess there are some risks by enabling them?
And why does the default route turn up as
B*    0.0.0.0/0 [200/0] via 10.0.0.1  when it should be
Gateway of last resort is 10.50.255.10 to network 0.0.0.0

Thank you

Highlighted
Cisco Employee

Good day, 

Good day, 

In order to have the default-route you need to include the default-information originate in OSPF. Otherwise the default route won't be included.

For the second second question, I know for sure that the idea to don't permit the internal routes to be added back in another IGP is to avoid any loop in the network. 

dal Participant
Participant

Hello.

Hello.

I works when I put the default-information originate in OSPF on both ends of the MPLS / BGP setup. That seems unnatural. default-information originate should be set only where the default route actually exists in my mind.

With EIGRP instead of OSPF I make this work by using these commands

router eigrp 1504
 !
 address-family ipv4 vrf VRF_NAME autonomous-system 50
  redistribute static metric 1000 200 250 250 9000
  redistribute connected
  network 10.50.0.0 0.0.255.255
 exit-address-family

ip route vrf VRF_NAME 0.0.0.0 0.0.0.0 10.50.255.10

This way I can see the default route on the other side and redistribute it further into the non MPLS enabled network without problems.

So if internal routes are not permitted into another IGP, how * SHOULD * I setup up my network?
I want to run MPLS across all my 15 L3-switches / routers.
Should each of the have their own AS number to make the network eBGP?

Thanks

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