11-12-2015 06:35 PM - edited 03-05-2019 02:44 AM
Please pardon me if my question is dumb as I am just new to BGP routing.
I have our HQ Routers 1 & 2 both running OSPF on area 0 with Partner Routers 1 & 2. ( See attached diagram). The same HQ Routers 1 & 2 also run eBGP with our branch routers BGP 65050. On HQ Router2 I am redistributing BGP to OSPF and vise versa. The routes on BGP 65000 are being redistributed to OSPF but the routes from AS 65050 (eBGP) are not getting redistributed so the Partner network is unable to reach the branch network.
Is is possible to redistribute eBGP routes to OSPF. If yes, how do I do it?
HQ Router 2:
router ospf 1
redistribute bgp 65000
router bgp 65000
redistribute ospf 1 route-map OSPF-TO-BGP
Solved! Go to Solution.
11-12-2015 06:41 PM
Hello
You can be its not recommended due to the size of the internet routing table.
However saying that you need to tell bgp to redistribute internally along with the other redistribute commands
router bgp xx
bgp redistribute-internal
res
paul
11-12-2015 07:35 PM
Hello,
you need do add "subnet" at the end of your redistribute command.
router ospf 1
redistribute bgp 65000 subnet.
If you do not specify "subnet", only classful subnets will be advertised.
Hope it helps,
Masoud
11-12-2015 06:41 PM
Hello
You can be its not recommended due to the size of the internet routing table.
However saying that you need to tell bgp to redistribute internally along with the other redistribute commands
router bgp xx
bgp redistribute-internal
res
paul
11-12-2015 06:51 PM
Hi Paul,
Thanks for the quick response. Our subnets are not advertised to the internet and I do not advertise the internet routes to our to private networks. I will try your advise. Tthanks again .
07-09-2024 10:16 AM
for Ebgp route redistribution , u dont need this command, u need it for ibgp
11-12-2015 07:35 PM
Hello,
you need do add "subnet" at the end of your redistribute command.
router ospf 1
redistribute bgp 65000 subnet.
If you do not specify "subnet", only classful subnets will be advertised.
Hope it helps,
Masoud
11-12-2015 07:45 PM
Thanks Masoud,
That did the trick, together with the bgp redistribute-internal.
Regards,
Gensonator
11-12-2015 07:49 PM
Glad it helped.
You do not need to add "bgp redistribute-internal". It is for redistributing IBGP to OSPF. It does not have any affact on EBGP.
http://www.cisco.com/c/en/us/td/docs/ios/12_2/iproute/command/reference/fiprrp_r/1rfbgp1.html
To allow the redistribution of iBGP routes into an interior gateway protocol such as IS-IS or OSPF, use the bgp redistribute-internal command in router configuration mode. To remove the bgp redistribute-internal command from the configuration file and restore the system to its default condition where the software does not allow the redistribution of iBGP routes into Interior Gateway Protocols (IGPs), use the no form of this command.
Masoud
11-12-2015 07:58 PM
I tried it but it does not work without "bgp redistribute-internal". I have been clearing both routing protocols (in a GNS test environment) to make sure changes take effect.
Tried "bgp redistribute-internal" only - not redistributing the ebgp routes
Tried "redistribute bgp 65000 subnets" only - not redistributing the ebgp routes
Tried using both - the ebgp routes have been redistributed.
11-12-2015 08:05 PM
Could you please share the output of the "show IP route on the router which you are doing redistribution.
I want to see some BGP routes in the routing table.
Let me also try it on GNS and get back to you.
Thanks
11-12-2015 08:48 PM
This is the routing table of the HQRouter2:
HQRouter2#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is 172.16.200.246 to network 0.0.0.0
192.168.14.0/29 is subnetted, 1 subnets
B 192.168.14.248 [200/0] via 172.16.200.246, 00:00:27
172.9.0.0/24 is subnetted, 1 subnets
O 172.9.200.0 [110/11] via 172.16.200.246, 00:37:04, FastEthernet0/0
172.16.0.0/30 is subnetted, 4 subnets
C 172.16.200.16 is directly connected, FastEthernet0/1
C 172.16.200.0 is directly connected, Vlan207
C 172.16.200.244 is directly connected, FastEthernet0/0
O 172.16.200.128 [110/11] via 172.16.200.246, 00:37:06, FastEthernet0/0
172.20.0.0/16 is variably subnetted, 3 subnets, 2 masks
B 172.20.40.0/24 [200/0] via 172.16.200.17, 00:00:29
B 172.20.16.0/24 [200/0] via 172.16.200.17, 00:00:29
B 172.20.120.0/21 [200/0] via 172.16.200.17, 00:00:29
163.189.0.0/32 is subnetted, 3 subnets
O 163.189.3.1 [110/12] via 10.92.30.1, 00:37:08, FastEthernet1/1
O 163.189.2.1 [110/12] via 10.92.30.1, 00:37:08, FastEthernet1/1
O 163.189.1.1 [110/12] via 10.92.30.1, 00:37:08, FastEthernet1/1
10.0.0.0/8 is variably subnetted, 9 subnets, 2 masks
O 10.10.1.0/30 [110/21] via 172.16.200.246, 00:37:08, FastEthernet0/0
O 10.10.2.0/30 [110/21] via 10.92.30.1, 00:37:08, FastEthernet1/1
O 10.10.3.0/30 [110/11] via 10.92.30.1, 00:37:08, FastEthernet1/1
O E2 10.1.3.0/24 [110/20] via 172.16.200.246, 00:37:08, FastEthernet0/0
O E2 10.1.1.0/24 [110/20] via 172.16.200.246, 00:37:08, FastEthernet0/0
B 10.92.0.120/30 [200/0] via 172.16.200.17, 00:00:30
O 10.92.30.8/30 [110/11] via 172.16.200.246, 00:37:08, FastEthernet0/0
C 10.92.30.0/30 is directly connected, FastEthernet1/1
B 10.92.0.4/30 [200/0] via 172.16.200.17, 00:00:30
O*E2 0.0.0.0/0 [110/1] via 172.16.200.246, 00:37:08, FastEthernet0/0
HQRouter2#
The routes for 172.20.16.0/24, 172.20.40.0/24, and 172.20.120/21 are from ebgp (not shown here). These are learned from an adjacent router that has the ebgp connection.
Here is its ip ospf database
HQRouter2#sh ip ospf database
OSPF Router with ID (172.16.200.245) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
10.10.2.1 10.10.2.1 522 0x80000004 0x00D3AF 2
10.92.30.1 10.92.30.1 1479 0x80000005 0x009035 2
10.92.30.9 10.92.30.9 492 0x80000005 0x00C28C 2
163.189.3.1 163.189.3.1 487 0x80000005 0x008DF1 5
172.16.200.17 172.16.200.17 1455 0x80000005 0x008544 1
172.16.200.245 172.16.200.245 531 0x8000000A 0x002217 4
192.168.21.250 192.168.21.250 447 0x80000005 0x001E49 4
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.10.1.1 10.92.30.9 494 0x80000003 0x00D41E
10.10.2.2 163.189.3.1 487 0x80000003 0x00360B
10.10.3.2 163.189.3.1 487 0x80000003 0x00745D
10.92.30.1 10.92.30.1 1479 0x80000002 0x005DD2
10.92.30.10 192.168.21.250 448 0x80000003 0x0060CB
172.16.200.17 172.16.200.17 1456 0x80000002 0x0009F3
172.16.200.246 192.168.21.250 448 0x80000003 0x00242C
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 192.168.21.250 450 0x80000003 0x0037F7 1
10.1.1.0 192.168.21.250 450 0x80000003 0x007717 130
10.1.3.0 192.168.21.250 450 0x80000003 0x00612B 130
HQRouter2#
As you can see, OSPF cannot see 172.20.16.0, 172.20.40.0 and 172.20.120.0.
Without "bgp redistribute-internal", the routes are not redistributed.
HQRouter2#sh run | before router
router ospf 1
log-adjacency-changes
redistribute static subnets route-map STATIC-TO-OSPF
redistribute bgp 65000 subnets
network 10.92.30.0 0.0.0.3 area 0
network 172.9.0.0 0.0.255.255 area 0
network 172.16.200.16 0.0.0.3 area 0
network 172.16.200.244 0.0.0.3 area 0
network 172.16.0.0 0.0.255.255 area 0
default-information originate route-map DEFAULT-TO-OSPF
!
router bgp 65000
no synchronization
bgp router-id 2.2.2.2
bgp log-neighbor-changes
network 172.9.0.0
network 172.16.200.244 mask 255.255.255.252
redistribute static route-map bgp-Redistribute-STATIC
redistribute ospf 1 route-map redistribute-OSPF-to-BGP
neighbor 172.16.200.17 remote-as 65000
neighbor 172.16.200.17 route-reflector-client
neighbor 172.16.200.17 next-hop-self
neighbor 172.16.200.17 soft-reconfiguration inbound
neighbor 172.16.200.17 route-map bgp-GSAGGR-import in
neighbor 172.16.200.246 remote-as 65000
neighbor 172.16.200.246 route-reflector-client
neighbor 172.16.200.246 next-hop-self
neighbor 172.16.200.246 soft-reconfiguration inbound
neighbor 172.16.200.246 route-map bgp-TMC-import in
no auto-summary
When I added "bgp redistribute-internal",
GS-CORE#sh ip ospf database
OSPF Router with ID (172.16.200.245) (Process ID 1)
Router Link States (Area 0)
Link ID ADV Router Age Seq# Checksum Link count
10.10.2.1 10.10.2.1 819 0x80000004 0x00D3AF 2
10.92.30.1 10.92.30.1 1776 0x80000005 0x009035 2
10.92.30.9 10.92.30.9 789 0x80000005 0x00C28C 2
163.189.3.1 163.189.3.1 785 0x80000005 0x008DF1 5
172.16.200.17 172.16.200.17 1752 0x80000005 0x008544 1
172.16.200.245 172.16.200.245 829 0x8000000A 0x002217 4
192.168.21.250 192.168.21.250 744 0x80000005 0x001E49 4
Net Link States (Area 0)
Link ID ADV Router Age Seq# Checksum
10.10.1.1 10.92.30.9 791 0x80000003 0x00D41E
10.10.2.2 163.189.3.1 785 0x80000003 0x00360B
10.10.3.2 163.189.3.1 785 0x80000003 0x00745D
10.92.30.1 10.92.30.1 1776 0x80000002 0x005DD2
10.92.30.10 192.168.21.250 746 0x80000003 0x0060CB
172.16.200.17 172.16.200.17 1754 0x80000002 0x0009F3
172.16.200.246 192.168.21.250 746 0x80000003 0x00242C
Type-5 AS External Link States
Link ID ADV Router Age Seq# Checksum Tag
0.0.0.0 192.168.21.250 747 0x80000003 0x0037F7 1
10.1.1.0 192.168.21.250 746 0x80000003 0x007717 130
10.1.3.0 192.168.21.250 746 0x80000003 0x00612B 130
10.92.0.4 172.16.200.245 70 0x80000001 0x0091A8 0
10.92.0.120 172.16.200.245 70 0x80000001 0x005AD6 7543
172.20.16.0 172.16.200.245 70 0x80000001 0x0091AA 7543
172.20.40.0 172.16.200.245 70 0x80000001 0x00889B 7543
172.20.120.0 172.16.200.245 70 0x80000001 0x00F1E8 7543
192.168.14.248 172.16.200.245 70 0x80000001 0x00054D 0
GS-CORE#
The routes are now redistributed.
It might have something to do with the other configuration on the router, or because I am not doing it on the router that has the ebgp connection.
11-12-2015 08:51 PM
Below is the routing table of the Partner Router when I use "bgp redistribute-internal" and "redistribute bgp 65000 subnet" together.
Partner-R2#sh ip route
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2
i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
ia - IS-IS inter area, * - candidate default, U - per-user static route
o - ODR, P - periodic downloaded static route
Gateway of last resort is 10.10.3.1 to network 0.0.0.0
192.168.14.0/29 is subnetted, 1 subnets
O E2 192.168.14.248 [110/1] via 10.10.3.1, 00:08:42, FastEthernet0/1
172.9.0.0/24 is subnetted, 1 subnets
O 172.9.200.0 [110/31] via 10.10.3.1, 00:53:56, FastEthernet0/1
172.16.0.0/30 is subnetted, 4 subnets
O 172.16.200.16 [110/30] via 10.10.3.1, 00:53:56, FastEthernet0/1
O 172.16.200.0 [110/21] via 10.10.3.1, 00:53:56, FastEthernet0/1
O 172.16.200.244 [110/30] via 10.10.3.1, 00:53:56, FastEthernet0/1
O 172.16.200.128 [110/31] via 10.10.3.1, 00:53:57, FastEthernet0/1
172.20.0.0/16 is variably subnetted, 3 subnets, 2 masks
O E2 172.20.40.0/24 [110/1] via 10.10.3.1, 00:08:44, FastEthernet0/1
O E2 172.20.16.0/24 [110/1] via 10.10.3.1, 00:08:44, FastEthernet0/1
O E2 172.20.120.0/21 [110/1] via 10.10.3.1, 00:08:44, FastEthernet0/1
163.189.0.0/24 is subnetted, 3 subnets
C 163.189.2.0 is directly connected, Loopback2
C 163.189.3.0 is directly connected, Loopback3
C 163.189.1.0 is directly connected, Loopback1
10.0.0.0/8 is variably subnetted, 9 subnets, 2 masks
O 10.10.1.0/30 [110/20] via 10.10.2.1, 00:54:00, FastEthernet0/0
C 10.10.2.0/30 is directly connected, FastEthernet0/0
C 10.10.3.0/30 is directly connected, FastEthernet0/1
O E2 10.1.3.0/24 [110/20] via 10.10.3.1, 00:54:00, FastEthernet0/1
O E2 10.1.1.0/24 [110/20] via 10.10.3.1, 00:54:00, FastEthernet0/1
O E2 10.92.0.120/30 [110/1] via 10.10.3.1, 00:08:47, FastEthernet0/1
O 10.92.30.8/30 [110/31] via 10.10.3.1, 00:54:00, FastEthernet0/1
O 10.92.30.0/30 [110/20] via 10.10.3.1, 00:54:00, FastEthernet0/1
O E2 10.92.0.4/30 [110/1] via 10.10.3.1, 00:08:47, FastEthernet0/1
O*E2 0.0.0.0/0 [110/1] via 10.10.3.1, 00:54:00, FastEthernet0/1
Partner-R2#
11-12-2015 08:55 PM
Thanks for sharing.
B 172.20.40.0/24 [200/0] via 172.16.200.17, 00:00:29
B 172.20.16.0/24 [200/0] via 172.16.200.17, 00:00:29
B 172.20.120.0/21 [200/0] via 172.16.200.17, 00:00:29
Actually, these routes are IBGP route. This is the reason it does not work without that command. As you see 200 is administrative distance for IBGP routes. Administrative distance for EBGP routes is 20.
router bgp 65000
no synchronization
bgp router-id 2.2.2.2
bgp log-neighbor-changes
network 172.9.0.0
network 172.16.200.244 mask 255.255.255.252
redistribute static route-map bgp-Redistribute-STATIC
redistribute ospf 1 route-map redistribute-OSPF-to-BGP
neighbor 172.16.200.17 remote-as 65000
This is an IBGP connection because your AS is the same as your neighbor AS.
Masoud
11-12-2015 09:03 PM
Yes, you are proven right. I put the command on the router below the HQRouter2 that has the ebgp relationship with the branch router and by just using the "redistribute bgp 65000 subnets" command, the ebgp routes have been redistributed to OSPF.
Thank you.
Cheers!
Gensonator
11-12-2015 09:05 PM
You are most welcome. Happy to help.
Masoud
11-12-2015 08:11 PM
Could you please try to use redistribute bgp 65000 subnets match external and see if that helps.
Regards
Vinit
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