Introduction
This document shows how to redistribute Internal BGP routes into OSPF process. Like in other IGP to IGP redistribution the behavior is different when redistributing IBGP into OSPF. IBGP learned routes are not forwarded to an IGP routing protocol through the redistribute command. Use command “bgp redistribute-internal” under the BGP process on the redistributing router.
In the scenario depicted here, router R1 and R2 are running IBGP and router R2/R3 running OSPF Area 0. R1 is advertising two routes (1.1.1.1 /32 and 172.16.0.0 /16) through network command. R2 is redistributing BGP into OSPF area 0. It is required to redistribute selected internal routes (172.16.0.0 /16). The task is achieved by making use of prefix-list and route-map.
A prefix-list, named B2O, is configured on R2 to match the prefix 172.16.0.0
ip prefix-list B2O seq 5 permit 172.16.0.0/16
A route-map, named BGP-To_OSPF, is configured on R2
route-map BGP-To_OSPF permit 10
match ip address prefix-list B2O
In the vrification section, please check the output of "show ip route" command on R3.
Prerequisite
- Understanding of routing protocols – BGP and OSPF
Topology Diagram
Configuration
Router R1
interface Loopback0 ip address 1.1.1.1 255.255.255.255 ! interface Loopback1 ip address 172.16.1.1 255.255.0.0 ! interface Serial1/0 ip address 192.12.12.1 255.255.255.0 serial restart-delay 0 ! router bgp 100 no synchronization bgp router-id 1.1.1.1 bgp log-neighbor-changes network 1.1.1.1 mask 255.255.255.255 network 172.16.0.0 neighbor 192.12.12.2 remote-as 100 no auto-summary
! |
Router R2
interface Loopback0 ip address 2.2.2.2 255.255.255.255 ! interface Serial1/0 ip address 192.12.12.2 255.255.255.0 serial restart-delay 0 ! interface FastEthernet2/0 ip address 192.23.23.2 255.255.255.0 duplex auto speed auto ! router ospf 1 router-id 2.2.2.2 log-adjacency-changes redistribute bgp 100 metric 100 metric-type 1 subnets route-map BGP-To_OSPF network 192.23.23.2 0.0.0.0 area 0 ! router bgp 100 no synchronization bgp router-id 2.2.2.2 bgp log-neighbor-changes bgp redistribute-internal neighbor 192.12.12.1 remote-as 100 no auto-summary ! ip prefix-list B2O seq 5 permit 172.16.0.0/16 ! route-map BGP-To_OSPF permit 10 match ip address prefix-list B2O ! |
Router R3
interface FastEthernet1/0 ip address 192.23.23.3 255.255.255.0 duplex auto speed auto ! router ospf 1 log-adjacency-changes network 192.23.23.3 0.0.0.0 area 0 |
Verification Commands
R1#sh ip bgp sum
BGP router identifier 1.1.1.1, local AS number 100
BGP table version is 3, main routing table version 3
2 network entries using 240 bytes of memory
2 path entries using 104 bytes of memory
1/1 BGP path/bestpath attribute entries using 124 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 468 total bytes of memory
BGP activity 2/0 prefixes, 2/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
192.12.12.2 4 100 117 119 3 0 0 01:43:47 0
R2#sh ip bgp sum
BGP router identifier 2.2.2.2, local AS number 100
BGP table version is 4, main routing table version 4
2 network entries using 240 bytes of memory
2 path entries using 104 bytes of memory
1/1 BGP path/bestpath attribute entries using 124 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 468 total bytes of memory
BGP activity 2/0 prefixes, 2/0 paths, scan interval 60 secs
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
192.12.12.1 4 100 119 118 4 0 0 01:43:36 2
R2#sh ip bgp
BGP table version is 4, local router ID is 2.2.2.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>i1.1.1.1/32 192.12.12.1 0 100 0 i
*>i172.16.0.0 192.12.12.1 0 100 0 i
R2#sh ip ospf ne
Neighbor ID Pri State Dead Time Address Interface
192.23.23.3 1 FULL/DR 00:00:35 192.23.23.3 FastEthernet2/0
R2#sh ip route 172.16.0.0
Routing entry for 172.16.0.0/16
Known via "bgp 100", distance 200, metric 0, type internal
Redistributing via ospf 1
Advertised by ospf 1 metric 100 metric-type 1 subnets route-map BGP-To_OSPF
Last update from 192.12.12.1 01:01:54 ago
Routing Descriptor Blocks:
* 192.12.12.1, from 192.12.12.1, 01:01:54 ago
Route metric is 0, traffic share count is 1
AS Hops 0
MPLS label: none
R3#sh ip route
Codes: L - local, 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, + - replicated route
Gateway of last resort is not set
O E1 172.16.0.0/16 [110/101] via 192.23.23.2, 00:57:55, FastEthernet1/0
192.23.23.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.23.23.0/24 is directly connected, FastEthernet1/0
L 192.23.23.3/32 is directly connected, FastEthernet1/0
Related Information
Hi I'm having the same issue. I'm pretty sure my redistribution from OSPF to BGP is wrong. not able to ping across gi0/0 of PE-1 from PC1. Topology is very similar. Configs and output below:
****PE-1******
!
vrf definition CustA_HQ
rd 100:10
route-target export 100:10
route-target import 100:10
route-target import 100:20
!
address-family ipv4
exit-address-family
!
vrf definition CustA_Remote
rd 100:20
route-target export 100:20
route-target import 100:20
!
interface Loopback0
description ///LOOPBACK0:MPLS-BGP///
ip address 1.1.1.1 255.255.255.255
!
interface Loopback10
description // VRF CustA_HQ - IGP LOOPBACK //
ip address 1.1.1.10 255.255.255.255
!
interface GigabitEthernet0/0
ip address 1.1.1.110 255.255.255.254
ip ospf network point-to-point
ip ospf 100 area 0
media-type gbic
speed 1000
duplex full
negotiation auto
!
interface GigabitEthernet1/0
vrf forwarding CustA_HQ
ip address 10.1.1.10 255.255.255.0
negotiation auto
!
router ospf 10 vrf CustA_HQ
router-id 1.1.1.10
log-adjacency-changes detail
redistribute bgp 100 metric 100 subnets route-map BGP_TO_OSPF
network 1.1.1.10 0.0.0.0 area 0
network 10.1.1.0 0.0.0.255 area 0
!
router ospf 100
router-id 1.1.1.1
log-adjacency-changes detail
network 1.1.1.1 0.0.0.0 area 0
!
router bgp 100
bgp log-neighbor-changes
neighbor 2.2.2.2 remote-as 100
neighbor 2.2.2.2 update-source Loopback0
!
address-family ipv4
bgp redistribute-internal
neighbor 2.2.2.2 activate
neighbor 2.2.2.2 send-community extended
exit-address-family
!
address-family vpnv4
neighbor 2.2.2.2 activate
neighbor 2.2.2.2 send-community extended
exit-address-family
!
address-family ipv4 vrf CustA_HQ
network 10.1.1.0 mask 255.255.255.0
redistribute ospf 10 metric 5
exit-address-family
!
ip prefix-list BGP_INTERNAL seq 5 permit 1.1.1.110/31
!
route-map BGP_TO_OSPF permit 10
match ip address prefix-list BGP_INTERNAL
!
%%%%%%%%%%PE-1 PINGS%%%%%%%%%%%%%
PE-1#ping vrf CustA_HQ 10.1.1.10
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.10, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/8 ms
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
PE-1#ping vrf CustA_HQ 10.1.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/28/48 ms
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
PE-1#ping vrf CustA_HQ 1.0.0.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.0.0.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/28/40 ms
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
PE-1#ping vrf CustA_HQ 1.0.0.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.0.0.2, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 24/299/1084 ms
%%%%%%%%%%%%%PE-1 ROUTES%%%%%%%%%%%%
PE-1#
PE-1#sh ip int brief
Interface IP-Address OK? Method Status Protocol
GigabitEthernet0/0 1.1.1.110 YES manual up up
GigabitEthernet1/0 10.1.1.10 YES manual up up
Loopback0 1.1.1.1 YES manual up up
Loopback10 1.1.1.10 YES manual up up
PE-1#
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
PE-1#sh ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
Gateway of last resort is not set
1.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
C 1.1.1.1/32 is directly connected, Loopback0
C 1.1.1.10/32 is directly connected, Loopback10
C 1.1.1.110/31 is directly connected, GigabitEthernet0/0
L 1.1.1.110/32 is directly connected, GigabitEthernet0/0
2.0.0.0/32 is subnetted, 1 subnets
O 2.2.2.2 [110/2] via 1.1.1.111, 03:12:06, GigabitEthernet0/0
111.0.0.0/32 is subnetted, 1 subnets
C 111.111.111.10 is directly connected, Loopback1
PE-1#
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
PE-1#sh ip bgp vpnv4 all
BGP table version is 3, local router ID is 1.1.1.10
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
Route Distinguisher: 100:10 (default for vrf CustA_HQ)
*> 1.0.0.0/29 10.1.1.1 5 32768 ?
*> 10.1.1.0/24 0.0.0.0 0 32768 I
***********************CustA-HQ*********************
hostname CustA-HQ
!
vrf definition CustA_HQ
rd 100:10
route-target export 100:10
route-target import 100:10
route-target import 100:20
!
address-family ipv4
exit-address-family
!
vrf definition CustA_Remote
rd 100:20
route-target export 100:20
route-target import 100:20
!
ip cef
no ipv6 cef
!
interface Loopback10
description // VRF CustA_HQ - IGP LOOPBACK //
ip address 10.10.10.10 255.255.255.255
!
interface GigabitEthernet0/0
vrf forwarding CustA_HQ
ip address 10.1.1.1 255.255.255.0
media-type gbic
speed 1000
duplex full
negotiation auto
!
interface FastEthernet1/0
vrf forwarding CustA_HQ
ip address 1.0.0.1 255.255.255.248
duplex full
!
router ospf 10 vrf CustA_HQ
router-id 10.10.10.10
log-adjacency-changes detail
network 1.0.0.0 0.0.0.7 area 0
network 10.1.1.0 0.0.0.255 area 0
network 10.10.10.10 0.0.0.0 area 0
!
control-plane
!
!
end
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CustA-HQ#sh ip route vrf CustA_HQ
Routing Table: CustA_HQ
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
Gateway of last resort is not set
1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 1.0.0.0/29 is directly connected, FastEthernet1/0
L 1.0.0.1/32 is directly connected, FastEthernet1/0
10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
C 10.1.1.0/24 is directly connected, GigabitEthernet0/0
L 10.1.1.1/32 is directly connected, GigabitEthernet0/0
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CustA-HQ#sh ip route
Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
Gateway of last resort is not set
10.0.0.0/32 is subnetted, 1 subnets
C 10.10.10.10 is directly connected, Loopback10
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CustA-HQ#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
1.1.1.10 1 FULL/DR 00:00:34 10.1.1.10 GigabitEthernet0/0
CustA-HQ#
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
CustA-HQ#sh ip route vrf CustA_HQ 1.1.1.110
Routing Table: CustA_HQ
% Subnet not in table
CustA-HQ#
CustA-HQ#
CustA-HQ#sh ip route 1.1.1.110
% Network not in table
CustA-HQ#
%%%%PINGS FROM PC CONNECTED TO CustA-HQ%%%%%%
PC1> ping 1.0.0.1
84 bytes from 1.0.0.1 icmp_seq=1 ttl=255 time=9.051 ms
84 bytes from 1.0.0.1 icmp_seq=2 ttl=255 time=9.007 ms
PC1> ping 10.1.1.1
84 bytes from 10.1.1.1 icmp_seq=1 ttl=255 time=15.626 ms
84 bytes from 10.1.1.1 icmp_seq=2 ttl=255 time=15.626 ms
PC1> ping 10.1.1.10
84 bytes from 10.1.1.10 icmp_seq=1 ttl=254 time=46.878 ms
84 bytes from 10.1.1.10 icmp_seq=2 ttl=254 time=31.246 ms
PC1> ping 1.1.1.110
*1.0.0.1 icmp_seq=1 ttl=255 time=15.626 ms (ICMP type:3, code:1, Destination host unreachable)
