The interfaces of P and PE routers are enabled for frame mode MPLS with the mpls ip interface subcommand and all P and PE routers use a common IGP (EIGRP with AS 200):
P#show mpls ldp neighbor
Peer LDP Ident: 1.1.1.1:0; Local LDP Ident 3.3.3.3:0
TCP connection: 1.1.1.1.646 - 3.3.3.3.33628
State: Oper; Msgs sent/rcvd: 10/11; Downstream
Up time: 00:01:54
LDP discovery sources:
Serial1/0, Src IP addr: 192.168.1.1
Addresses bound to peer LDP Ident:
10.1.1.1 192.168.1.1 1.1.1.1
Peer LDP Ident: 2.2.2.2:0; Local LDP Ident 3.3.3.3:0
TCP connection: 2.2.2.2.646 - 3.3.3.3.17194
State: Oper; Msgs sent/rcvd: 9/10; Downstream
Up time: 00:01:19
LDP discovery sources:
Serial1/1, Src IP addr: 192.168.2.1
Addresses bound to peer LDP Ident:
10.2.2.1 192.168.2.1 2.2.2.2
P#
PE1#show mpls ldp neighbor
Peer LDP Ident: 3.3.3.3:0; Local LDP Ident 1.1.1.1:0
TCP connection: 3.3.3.3.33628 - 1.1.1.1.646
State: Oper; Msgs sent/rcvd: 10/9; Downstream
Up time: 00:01:43
LDP discovery sources:
Serial1/0, Src IP addr: 192.168.1.2
Addresses bound to peer LDP Ident:
192.168.1.2 192.168.2.2 3.3.3.3
PE1#
PE2#show mpls ldp neighbor
Peer LDP Ident: 3.3.3.3:0; Local LDP Ident 2.2.2.2:0
TCP connection: 3.3.3.3.17194 - 2.2.2.2.646
State: Oper; Msgs sent/rcvd: 10/9; Downstream
Up time: 00:01:13
LDP discovery sources:
Serial1/0, Src IP addr: 192.168.2.2
Addresses bound to peer LDP Ident:
192.168.1.2 192.168.2.2 3.3.3.3
PE2#
PE1#show mpls forwarding-table
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or Tunnel Id Switched interface
16 Pop Label 3.3.3.0/24 0 Se1/0 point2point
17 Pop Label 192.168.2.0/24 0 Se1/0 point2point
18 17 2.2.2.0/24 0 Se1/0 point2point
PE1#
PE2#show mpls forwarding-table
Local Outgoing Prefix Bytes Label Outgoing Next Hop
Label Label or Tunnel Id Switched interface
16 Pop Label 3.3.3.0/24 0 Se1/0 point2point
17 Pop Label 192.168.1.0/24 0 Se1/0 point2point
18 16 1.1.1.0/24 0 Se1/0 point2point
PE2#
Configuration of VRF:
Create each VRF, RD, and RT, plus associating the customer-facing PE interfaces with the correct VRF:
VRF CUST-A, RD 1:111, RT 1:100
VRF CUST-B, RD 2:222, RT 2:200
PE1
ip vrf CUST-A
rd 1:111
route-target export 1:100
route-target import 1:100
!
ip vrf CUST-B
rd 2:222
route-target export 2:200
route-target import 2:200
!
interface FastEthernet0/0
ip vrf forwarding CUST-A
ip address 10.1.1.1 255.255.255.0
!
interface FastEthernet0/1
ip vrf forwarding CUST-B
ip address 10.3.3.1 255.255.255.0
PE2
ip vrf CUST-A
rd 1:111
route-target export 1:100
route-target import 1:100
!
ip vrf CUST-B
rd 2:222
route-target export 2:200
route-target import 2:200
!
interface FastEthernet0/0
ip vrf forwarding CUST-A
ip address 10.2.2.1 255.255.255.0
!
interface FastEthernet0/1
ip vrf forwarding CUST-B
ip address 10.4.4.1 255.255.255.0
Configuring the IGP Between PE and CE routers
I am using OSPFv3 address families between CEs and PEs routers:
CE-A1:
interface Loopback0
ospfv3 1 ipv4 area 0
!
interface FastEthernet0/0
ipv6 enable
ospfv3 1 ipv4 area 0
!
router ospfv3 1
!
address-family ipv4 unicast
exit-address-family
CE-A2:
interface Loopback0
ospfv3 1 ipv4 area 0
!
interface FastEthernet0/0
ipv6 enable
ospfv3 1 ipv4 area 0
!
router ospfv3 1
!
address-family ipv4 unicast
exit-address-family
PE1:
interface FastEthernet0/0
ipv6 enable
ospfv3 1 ipv4 area 0
!
interface FastEthernet0/1
ipv6 enable
ospfv3 1 ipv4 area 0
!
router ospfv3 1
!
address-family ipv4 unicast vrf CUST-B
exit-address-family
!
address-family ipv4 unicast vrf CUST-A
exit-address-family
PE2:
interface FastEthernet0/0
ipv6 enable
ospfv3 1 ipv4 area 0
!
interface FastEthernet0/1
ipv6 enable
ospfv3 1 ipv4 area 0
!
router ospfv3 1
!
address-family ipv4 unicast vrf CUST-B
exit-address-family
!
address-family ipv4 unicast vrf CUST-A
exit-address-family
Verify the OSPFv3 neighbors for each VRF on the PE routers:
PE1#show ospfv3 vrf CUST-A neighbor
OSPFv3 1 address-family ipv4 vrf CUST-A (router-id 10.1.1.1)
Neighbor ID Pri State Dead Time Interface ID Interface
172.16.1.1 1 FULL/DR 00:00:30 2 FastEthernet0/0
PE1#
PE1#show ospfv3 vrf CUST-B neighbor
OSPFv3 1 address-family ipv4 vrf CUST-B (router-id 10.3.3.1)
Neighbor ID Pri State Dead Time Interface ID Interface
172.16.1.1 1 FULL/DR 00:00:36 2 FastEthernet0/1
PE1#
PE2#show ospfv3 vrf CUST-A neighbor
OSPFv3 1 address-family ipv4 vrf CUST-A (router-id 10.2.2.1)
Neighbor ID Pri State Dead Time Interface ID Interface
172.16.2.1 1 FULL/DR 00:00:35 2 FastEthernet0/0
PE2#
PE2#show ospfv3 vrf CUST-B neighbor
OSPFv3 1 address-family ipv4 vrf CUST-B (router-id 10.4.4.1)
Neighbor ID Pri State Dead Time Interface ID Interface
172.16.2.1 1 FULL/DR 00:00:39 2 FastEthernet0/1
PE2#
The PE routers create two separate LSDB for each VRF customers as shown by the following output on PE1 router:
PE1#show ospfv3 vrf CUST-A database
OSPFv3 1 address-family ipv4 vrf CUST-A (router-id 10.1.1.1)
Router Link States (Area 0)
ADV Router Age Seq# Fragment ID Link count Bits
10.1.1.1 603 0x80000002 0 1 B
172.16.1.1 609 0x80000002 0 1 None
Net Link States (Area 0)
ADV Router Age Seq# Link ID Rtr count
172.16.1.1 608 0x80000001 2 2
Link (Type-8) Link States (Area 0)
ADV Router Age Seq# Link ID Interface
10.1.1.1 608 0x80000001 2 Fa0/0
172.16.1.1 990 0x80000001 2 Fa0/0
Intra Area Prefix Link States (Area 0)
ADV Router Age Seq# Link ID Ref-lstype Ref-LSID
172.16.1.1 608 0x80000003 0 0x2001 0
172.16.1.1 608 0x80000001 2048 0x2002 2
PE1#
The show ospfv3 vrf CUST-A command shown that the MPLS VPN backbone acts as a Super Backbone, therefore the PE routers act as an ABR, notice the lines "Connected to
MPLS VPN Superbackbone" and "It is an area border router".
PE1#show ospfv3 vrf CUST-A
OSPFv3 1 address-family ipv4 vrf CUST-A
Router ID 10.1.1.1
Supports NSSA (compatible with RFC 3101)
Domain ID (none)
Connected to MPLS VPN Superbackbone
Event-log enabled, Maximum number of events: 1000, Mode: cyclic
It is an area border router
Router is not originating router-LSAs with maximum metric
Initial SPF schedule delay 5000 msecs
Minimum hold time between two consecutive SPFs 10000 msecs
Maximum wait time between two consecutive SPFs 10000 msecs
Minimum LSA interval 5 secs
Minimum LSA arrival 1000 msecs
LSA group pacing timer 240 secs
Interface flood pacing timer 33 msecs
Retransmission pacing timer 66 msecs
Retransmission limit dc 24 non-dc 24
Number of external LSA 0. Checksum Sum 0x000000
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Graceful restart helper support enabled
Reference bandwidth unit is 100 mbps
RFC1583 compatibility enabled
Area BACKBONE(0)
Number of interfaces in this area is 1
SPF algorithm executed 2 times
Number of LSA 7. Checksum Sum 0x0340D2
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0
PE1#
The LSA Type 1 generated by PE1 router confirms that the B-bit has been set to 1 to tell to the CE routers that it is an ABR, notice the line "Area Border Router".
PE1#show ospfv3 vrf CUST-A database router self-originate
OSPFv3 1 address-family ipv4 vrf CUST-A (router-id 10.1.1.1)
Router Link States (Area 0)
LS age: 908
Options: (E-Bit, R-bit, DC-Bit, AF-Bit)
LS Type: Router Links
Link State ID: 0
Advertising Router: 10.1.1.1
LS Seq Number: 80000002
Checksum: 0x35F7
Length: 40
Area Border Router
Number of Links: 1
Link connected to: a Transit Network
Link Metric: 1
Local Interface ID: 2
Neighbor (DR) Interface ID: 2
Neighbor (DR) Router ID: 172.16.1.1
PE1#
Verify the IP routes for each VRF:
PE1#show ip route vrf CUST-A ospfv3
Routing Table: CUST-A
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, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
172.16.0.0/32 is subnetted, 1 subnets
O 172.16.1.1 [110/1] via 10.1.1.2, 00:19:40, FastEthernet0/0
PE1#
PE1#show ip route vrf CUST-B ospfv3
Routing Table: CUST-B
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, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
172.16.0.0/32 is subnetted, 1 subnets
O 172.16.1.1 [110/1] via 10.3.3.2, 00:19:52, FastEthernet0/1
PE1#
PE2#show ip route vrf CUST-A ospfv3
Routing Table: CUST-A
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, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
172.16.0.0/32 is subnetted, 1 subnets
O 172.16.2.1 [110/1] via 10.2.2.2, 00:20:02, FastEthernet0/0
PE2#
PE2#show ip route vrf CUST-B ospfv3
Routing Table: CUST-B
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, H - NHRP, l - LISP
+ - replicated route, % - next hop override
Gateway of last resort is not set
172.16.0.0/32 is subnetted, 1 subnets
O 172.16.2.1 [110/1] via 10.4.4.2, 00:20:36, FastEthernet0/1
PE2#
Redistribution Between PE-CE routers (between OSPFv3 and MP-BGP):
PE1(config)#router bgp 65000
PE1(config-router)#address-family ipv4 vrf CUST-A
PE1(config-router-af)#redistribute ospfv3 1
PE1(config-router-af)#address-family ipv4 vrf CUST-B
PE1(config-router-af)#redistribute ospfv3 1
PE1(config-router-af)#router ospfv3 1
PE1(config-router)#address-family ipv4 vrf CUST-A
PE1(config-router-af)#redistribute bgp 65000
PE1(config-router-af)#address-family ipv4 vrf CUST-B
PE1(config-router-af)#redistribute bgp 65000
PE2(config)#router bgp 65000
PE2(config-router)#address-family ipv4 vrf CUST-A
PE2(config-router-af)#redistribute ospfv3 1
PE2(config-router-af)#address-family ipv4 vrf CUST-B
PE2(config-router-af)#redistribute ospfv3 1
PE2(config-router-af)#router ospfv3 1
PE2(config-router)#address-family ipv4 vrf CUST-A
PE2(config-router-af)#redistribute bgp 65000
PE2(config-router-af)#address-family ipv4 vrf CUST-B
PE2(config-router-af)#redistribute bgp 65000
Configuration MP-BGP Between PEs routers:
PE1(config)#router bgp 65000
PE1(config-router)#neighbor 2.2.2.2 remote-as 65000
PE1(config-router)#neighbor 2.2.2.2 update-source loop0
PE1(config-router)#address-family vpnv4
PE1(config-router-af)#neighbor 2.2.2.2 activate
PE1(config-router-af)#neighbor 2.2.2.2 send-community
PE2(config)#router bgp 65000
PE2(config-router)#neighbor 1.1.1.1 remote-as 65000
PE2(config-router)#neighbor 1.1.1.1 update-source loop0
PE2(config-router)#address-family vpnv4
PE2(config-router-af)#neighbor 1.1.1.1 activate
PE2(config-router-af)#neighbor 1.1.1.1 send-community
Verify the BGP neighbor:
PE1#show ip bgp summary
BGP router identifier 1.1.1.1, local AS number 65000
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
2.2.2.2 4 65000 17 9 1 0 0 00:00:46 0
PE1#
PE2#show ip bgp summary
BGP router identifier 2.2.2.2, local AS number 65000
BGP table version is 1, main routing table version 1
Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd
1.1.1.1 4 65000 10 17 1 0 0 00:01:20 0
PE2#
Verify the per-RD BGP table. And we can see the overlapping subnets 172.16.1.1/32 and 172.16.2.1/32 are a part of the two customers’ address spaces:
PE1#show ip bgp vpnv4 all
BGP table version is 13, local router ID is 1.1.1.1
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: 1:111 (default for vrf CUST-A)
*> 10.1.1.0/24 0.0.0.0 0 32768 ?
*>i 10.2.2.0/24 2.2.2.2 0 100 0 ?
*> 172.16.1.1/32 10.1.1.2 1 32768 ?
*>i 172.16.2.1/32 2.2.2.2 1 100 0 ?
Route Distinguisher: 2:222 (default for vrf CUST-B)
*> 10.3.3.0/24 0.0.0.0 0 32768 ?
*>i 10.4.4.0/24 2.2.2.2 0 100 0 ?
*> 172.16.1.1/32 10.3.3.2 1 32768 ?
*>i 172.16.2.1/32 2.2.2.2 1 100 0 ?
PE1#
PE2#show ip bgp vpnv4 all
BGP table version is 13, 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, 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: 1:111 (default for vrf CUST-A)
*>i 10.1.1.0/24 1.1.1.1 0 100 0 ?
*> 10.2.2.0/24 0.0.0.0 0 32768 ?
*>i 172.16.1.1/32 1.1.1.1 1 100 0 ?
*> 172.16.2.1/32 10.2.2.2 1 32768 ?
Route Distinguisher: 2:222 (default for vrf CUST-B)
*>i 10.3.3.0/24 1.1.1.1 0 100 0 ?
*> 10.4.4.0/24 0.0.0.0 0 32768 ?
*>i 172.16.1.1/32 1.1.1.1 1 100 0 ?
*> 172.16.2.1/32 10.4.4.2 1 32768 ?
PE2#
Verify the the per-VRF routing tables of PEs routers, they receive both the BGP routes toward 172.16.1.1/32 and 172.16.2.1/32 for each VRF:
PE1#show ip route vrf CUST-A | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
C 10.1.1.0/24 is directly connected, FastEthernet0/0
L 10.1.1.1/32 is directly connected, FastEthernet0/0
B 10.2.2.0/24 [200/0] via 2.2.2.2, 00:05:21
172.16.0.0/32 is subnetted, 2 subnets
O 172.16.1.1 [110/1] via 10.1.1.2, 00:09:55, FastEthernet0/0
B 172.16.2.1 [200/1] via 2.2.2.2, 00:05:21
PE1#
PE1#show ip route vrf CUST-B | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
C 10.3.3.0/24 is directly connected, FastEthernet0/1
L 10.3.3.1/32 is directly connected, FastEthernet0/1
B 10.4.4.0/24 [200/0] via 2.2.2.2, 00:06:24
172.16.0.0/32 is subnetted, 2 subnets
O 172.16.1.1 [110/1] via 10.3.3.2, 00:10:50, FastEthernet0/1
B 172.16.2.1 [200/1] via 2.2.2.2, 00:06:24
PE1#
PE2#show ip route vrf CUST-A | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
B 10.1.1.0/24 [200/0] via 1.1.1.1, 00:07:41
C 10.2.2.0/24 is directly connected, FastEthernet0/0
L 10.2.2.1/32 is directly connected, FastEthernet0/0
172.16.0.0/32 is subnetted, 2 subnets
B 172.16.1.1 [200/1] via 1.1.1.1, 00:07:41
O 172.16.2.1 [110/1] via 10.2.2.2, 00:10:45, FastEthernet0/0
PE2#
PE2#show ip route vrf CUST-B | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
B 10.3.3.0/24 [200/0] via 1.1.1.1, 00:07:46
C 10.4.4.0/24 is directly connected, FastEthernet0/1
L 10.4.4.1/32 is directly connected, FastEthernet0/1
172.16.0.0/32 is subnetted, 2 subnets
B 172.16.1.1 [200/1] via 1.1.1.1, 00:07:46
O 172.16.2.1 [110/1] via 10.4.4.2, 00:10:46, FastEthernet0/1
PE2#
Verify that the customer routers have learned the routes from each customer router in the same VRF:
By definition when the PE router redistributes the VPNv4 routes to the OSPF domain, it checks the Domain ID to decide whether the routes should be redistributed as inter-area (same Domain ID) or external (different Domain ID) routes to the CE router.
Each OSPF instance must be assigned a unique Domain ID. On Cisco routers, the OSPF Domain ID is the OSPF Process ID by default. When BGP distributes VPNv4 routes to other PE routers, the Domain ID is carried with the routes as extended community.
Since the Domain IDs on both PE routers match , PE routers redistributes the subnets 172.16.1.1/32 and 172.16.2.1/32 to CE routers as inter-area routes (LSA Type 3) as shown by the routing tables of the CE routers:
CE-A1# show ip route OSPFv3 | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O IA 10.2.2.0/24 [110/2] via 10.1.1.1, 00:09:48, FastEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.16.2.1/32 [110/2] via 10.1.1.1, 00:09:48, FastEthernet0/0
CE-A1#
CE-A2#show ip route OSPFv3 | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O IA 10.1.1.0/24 [110/2] via 10.2.2.1, 00:10:53, FastEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.16.1.1/32 [110/2] via 10.2.2.1, 00:10:53, FastEthernet0/0
CE-A2#
CE-B1#show ip route OSPFv3 | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O IA 10.4.4.0/24 [110/2] via 10.3.3.1, 00:11:53, FastEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.16.2.1/32 [110/2] via 10.3.3.1, 00:11:53, FastEthernet0/0
CE-B1#
CE-B2#show ip route OSPFv3 | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O IA 10.3.3.0/24 [110/2] via 10.4.4.1, 00:12:54, FastEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.16.1.1/32 [110/2] via 10.4.4.1, 00:12:54, FastEthernet0/0
CE-B2#
Verify the connectivity between the customers:
CE-A1#ping 172.16.2.1 sou 172.16.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.2.1, timeout is 2 seconds:
Packet sent with a source address of 172.16.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 156/188/224 ms
CE-A1#
CE-B1#ping 172.16.2.1 sou 172.16.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.2.1, timeout is 2 seconds:
Packet sent with a source address of 172.16.1.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 184/284/356 ms
CE-B1#
The above following output shown that PE2 router is advertising the 172.16.2.1/32 prefixes for each VRF to PE1 using BGP. PE2 has included all OSPF related BGP
Extended communities. The route-type is set as LSA Type-2 (intra-area) route as shown by the line: OSPF RT:0.0.0.0:2:0. The Router ID is the router-id of PE2 router set for that VRF instance (ROUTER ID:10.2.2.1:0 for VRF CUST-A and ROUTER ID:10.4.4.1:0 for VRF CUST-B).
PE1#show ip bgp vpnv4 all 172.16.2.1
BGP routing table entry for 1:111:172.16.2.1/32, version 11
Paths: (1 available, best #1, table CUST-A)
Not advertised to any peer
Refresh Epoch 1
Local
2.2.2.2 (metric 2809856) from 2.2.2.2 (2.2.2.2)
Origin incomplete, metric 1, localpref 100, valid, internal, best
Extended Community: RT:1:100 OSPF ROUTER ID:10.2.2.1:0
OSPF RT:0.0.0.0:2:0
mpls labels in/out nolabel/21
rx pathid: 0, tx pathid: 0x0
BGP routing table entry for 2:222:172.16.2.1/32, version 13
Paths: (1 available, best #1, table CUST-B)
Not advertised to any peer
Refresh Epoch 1
Local
2.2.2.2 (metric 2809856) from 2.2.2.2 (2.2.2.2)
Origin incomplete, metric 1, localpref 100, valid, internal, best
Extended Community: RT:2:200 OSPF ROUTER ID:10.4.4.1:0
OSPF RT:0.0.0.0:2:0
mpls labels in/out nolabel/20
rx pathid: 0, tx pathid: 0x0
PE1#
Since the Domain IDs on both PE routers match, the CE routers receives the prefixes 172.16.1.1/32 and 172.16.2.1/32 as inter-area routes as shown by the routing table
of the CE-A1 router for the prefix 172.16.2.1/32:
CE-A1#show ip route 172.16.2.1
Routing entry for 172.16.2.1/32
Known via "ospfv3 1", distance 110, metric 2, type inter area
Last update from 10.1.1.1 on FastEthernet0/0, 00:23:04 ago
Routing Descriptor Blocks:
* 10.1.1.1, from 10.1.1.1, 00:23:04 ago, via FastEthernet0/0
Route metric is 2, traffic share count is 1
CE-A1#
Verify that PE1 router created the Summary LSA Type 3 for the prefix 172.16.2.1/32 with the show ospfv3 vrf CUST-A database inter-area prefix command:
PE1#show ospfv3 vrf CUST-A database inter-area prefix
OSPFv3 1 address-family ipv4 vrf CUST-A (router-id 10.1.1.1)
Inter Area Prefix Link States (Area 0)
LS age: 1519
LS Type: Inter Area Prefix Links
Link State ID: 0
Advertising Router: 10.1.1.1
LS Seq Number: 80000001
Checksum: 0x10E6
Length: 32
Metric: 1
Prefix Address: 10.2.2.0
Prefix Length: 24, Options: DN
LS age: 1519
LS Type: Inter Area Prefix Links
Link State ID: 1
Advertising Router: 10.1.1.1
LS Seq Number: 80000001
Checksum: 0xF14A
Length: 32
Metric: 1
Prefix Address: 172.16.2.1
Prefix Length: 32, Options: DN
PE1#
Verify the LSDB of the PE1 router for the VRF CUST-A:
PE1#show ospfv3 vrf CUST-A database
OSPFv3 1 address-family ipv4 vrf CUST-A (router-id 10.1.1.1)
Router Link States (Area 0)
ADV Router Age Seq# Fragment ID Link count Bits
10.1.1.1 1903 0x80000004 0 1 B E
172.16.1.1 172 0x80000004 0 1 None
Net Link States (Area 0)
ADV Router Age Seq# Link ID Rtr count
172.16.1.1 172 0x80000003 2 2
Inter Area Prefix Link States (Area 0)
ADV Router Age Seq# Prefix
10.1.1.1 1624 0x80000001 10.2.2.0/24
10.1.1.1 1624 0x80000001 172.16.2.1/32
Link (Type-8) Link States (Area 0)
ADV Router Age Seq# Link ID Interface
10.1.1.1 1989 0x80000002 2 Fa0/0
172.16.1.1 430 0x80000003 2 Fa0/0
Intra Area Prefix Link States (Area 0)
ADV Router Age Seq# Link ID Ref-lstype Ref-LSID
172.16.1.1 172 0x80000005 0 0x2001 0
172.16.1.1 172 0x80000003 2048 0x2002 2
PE1#
PE1#show ip bgp vpnv4 vrf CUST-A 172.16.2.1
BGP routing table entry for 1:111:172.16.2.1/32, version 11
Paths: (1 available, best #1, table CUST-A)
Not advertised to any peer
Refresh Epoch 1
Local
2.2.2.2 (metric 2809856) from 2.2.2.2 (2.2.2.2)
Origin incomplete, metric 1, localpref 100, valid, internal, best
Extended Community: RT:1:100 OSPF ROUTER ID:10.2.2.1:0
OSPF RT:0.0.0.0:2:0
mpls labels in/out nolabel/21
rx pathid: 0, tx pathid: 0x0
PE1#
Configure the Domain ID manually with the value 000000000310 for the VRF CUST-A on PE2 router:
PE2(config-router)#router ospfv3 1
PE2(config-router)#address-family ipv4 vrf CUST-A
PE2(config-router-af)#domain-id type 0005 value 000000000310
PE2 router advertises the 172.16.2.1/32 prefix for the VRF CUST-A with Domain ID 000000000309. PE1 matches that with its own Domain ID (which is by default is equal to 1 the process ID of OSPF) before redistributing the prefix to CE-A1 router. Since the Domain IDs dont match, PE1 advertises the prefix as an External Type-2 prefix to CE-A1 router as shown by the following output below and notice the prefix 172.16.2.1/32 for the VRF CUST-B is advertised with the default domain ID by PE2 router.
PE1#show ip bgp vpnv4 all 172.16.2.1/32
BGP routing table entry for 1:111:172.16.2.1/32, version 15
Paths: (1 available, best #1, table CUST-A)
Not advertised to any peer
Refresh Epoch 1
Local
2.2.2.2 (metric 2809856) from 2.2.2.2 (2.2.2.2)
Origin incomplete, metric 1, localpref 100, valid, internal, best
Extended Community: RT:1:100 OSPF DOMAIN ID:0x0005:0x000000000310
OSPF ROUTER ID:10.2.2.1:0 OSPF RT:0.0.0.0:2:0
mpls labels in/out nolabel/21
rx pathid: 0, tx pathid: 0x0
BGP routing table entry for 2:222:172.16.2.1/32, version 13
Paths: (1 available, best #1, table CUST-B)
Not advertised to any peer
Refresh Epoch 1
Local
2.2.2.2 (metric 2809856) from 2.2.2.2 (2.2.2.2)
Origin incomplete, metric 1, localpref 100, valid, internal, best
Extended Community: RT:2:200 OSPF ROUTER ID:10.4.4.1:0
OSPF RT:0.0.0.0:2:0
mpls labels in/out nolabel/20
rx pathid: 0, tx pathid: 0x0
PE1#
We can display only the entry for the 172.16.2.1/32 prefix in VRF CUST-A using the show ip bgp vpnv4 vrf CUST-A 172.16.2.1 command:
PE1#show ip bgp vpnv4 vrf CUST-A 172.16.2.1
BGP routing table entry for 1:111:172.16.2.1/32, version 15
Paths: (1 available, best #1, table CUST-A)
Not advertised to any peer
Refresh Epoch 1
Local
2.2.2.2 (metric 2809856) from 2.2.2.2 (2.2.2.2)
Origin incomplete, metric 1, localpref 100, valid, internal, best
Extended Community: RT:1:100 OSPF DOMAIN ID:0x0005:0x000000000310
OSPF ROUTER ID:10.2.2.1:0 OSPF RT:0.0.0.0:2:0
mpls labels in/out nolabel/21
rx pathid: 0, tx pathid: 0x0
PE1#
And we can verify that CE-A1 router received an external route for the prefix 172.16.2.1/32 as shown by its routing table:
CE-A1#show ip route ospfv3 | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O E2 10.2.2.0/24 [110/1] via 10.1.1.1, 00:00:31, FastEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O E2 172.16.2.1/32 [110/1] via 10.1.1.1, 00:00:31, FastEthernet0/0
CE-A1#
CE-A1#show ip route 172.16.2.1
Routing entry for 172.16.2.1/32
Known via "ospfv3 1", distance 110, metric 1, type extern 2, forward metric 1
Last update from 10.1.1.1 on FastEthernet0/0, 00:01:28 ago
Routing Descriptor Blocks:
* 10.1.1.1, from 10.1.1.1, 00:01:28 ago, via FastEthernet0/0
Route metric is 1, traffic share count is 1
CE-A1#
Verify that PE1 router is advertising an LSA Type 5 for the 172.16.2.1/32 prefix:
PE1#show ospfv3 vrf CUST-A database external
OSPFv3 1 address-family ipv4 vrf CUST-A (router-id 10.1.1.1)
Type-5 AS External Link States
LS age: 5
LS Type: AS External Link
Link State ID: 0
Advertising Router: 10.1.1.1
LS Seq Number: 80000001
Checksum: 0x1EB2
Length: 32
Prefix Address: 10.2.2.0
Prefix Length: 24, Options: DN
Metric Type: 2 (Larger than any link state path)
Metric: 1
LS age: 5
LS Type: AS External Link
Link State ID: 1
Advertising Router: 10.1.1.1
LS Seq Number: 80000001
Checksum: 0xFF16
Length: 32
Prefix Address: 172.16.2.1
Prefix Length: 32, Options: DN
Metric Type: 2 (Larger than any link state path)
Metric: 1
PE1#
Verify the LSDB of the VRF CUST-A on PE1 router and the LSA Type 5:
PE1#show ospfv3 vrf CUST-A database
OSPFv3 1 address-family ipv4 vrf CUST-A (router-id 10.1.1.1)
Router Link States (Area 0)
ADV Router Age Seq# Fragment ID Link count Bits
10.1.1.1 892 0x80000005 0 1 B E
172.16.1.1 1087 0x80000004 0 1 None
Net Link States (Area 0)
ADV Router Age Seq# Link ID Rtr count
172.16.1.1 1087 0x80000003 2 2
Link (Type-8) Link States (Area 0)
ADV Router Age Seq# Link ID Interface
10.1.1.1 892 0x80000003 2 Fa0/0
172.16.1.1 1345 0x80000003 2 Fa0/0
Intra Area Prefix Link States (Area 0)
ADV Router Age Seq# Link ID Ref-lstype Ref-LSID
172.16.1.1 1087 0x80000005 0 0x2001 0
172.16.1.1 1087 0x80000003 2048 0x2002 2
Type-5 AS External Link States
ADV Router Age Seq# Prefix
10.1.1.1 539 0x80000001 10.2.2.0/24
10.1.1.1 539 0x80000001 172.16.2.1/32
PE1#
Verify that the prefix 172.16.2.1/32 is advertised as inter-area route for VRF CUST-B by looking the LSBD for VRF CUST-B, because simply the prefix 172.16.2.1/32 for the VRF CUST-B is advertised with the default domain ID by PE2 router:
PE1#show ospfv3 vrf CUST-B database
OSPFv3 1 address-family ipv4 vrf CUST-B (router-id 10.3.3.1)
Router Link States (Area 0)
ADV Router Age Seq# Fragment ID Link count Bits
10.3.3.1 850 0x80000005 0 1 B E
172.16.1.1 808 0x80000004 0 1 None
Net Link States (Area 0)
ADV Router Age Seq# Link ID Rtr count
172.16.1.1 808 0x80000003 2 2
Inter Area Prefix Link States (Area 0)
ADV Router Age Seq# Prefix
10.3.3.1 608 0x80000002 10.4.4.0/24
10.3.3.1 608 0x80000002 172.16.2.1/32
Link (Type-8) Link States (Area 0)
ADV Router Age Seq# Link ID Interface
10.3.3.1 850 0x80000003 3 Fa0/1
172.16.1.1 1067 0x80000003 2 Fa0/1
Intra Area Prefix Link States (Area 0)
ADV Router Age Seq# Link ID Ref-lstype Ref-LSID
172.16.1.1 808 0x80000005 0 0x2001 0
172.16.1.1 809 0x80000003 2048 0x2002 2
PE1#
At the other side, PE2 router advertises an LSA Type 5 for the prefix 172.16.1.1/32 into VRF CUST-A because the PE1 advertises it with the default domain ID 1 and PE2's domain ID has been changed earlier to be 000000000310 for VRF CUST-A:
PE2#show ospfv3 vrf CUST-A database
OSPFv3 1 address-family ipv4 vrf CUST-A (router-id 10.2.2.1)
Router Link States (Area 0)
ADV Router Age Seq# Fragment ID Link count Bits
10.2.2.1 1015 0x80000005 0 1 B E
172.16.2.1 1070 0x80000004 0 1 None
Net Link States (Area 0)
ADV Router Age Seq# Link ID Rtr count
172.16.2.1 1070 0x80000003 2 2
Link (Type-8) Link States (Area 0)
ADV Router Age Seq# Link ID Interface
10.2.2.1 1015 0x80000003 2 Fa0/0
172.16.2.1 1330 0x80000003 2 Fa0/0
Intra Area Prefix Link States (Area 0)
ADV Router Age Seq# Link ID Ref-lstype Ref-LSID
172.16.2.1 1070 0x80000005 0 0x2001 0
172.16.2.1 1070 0x80000003 2048 0x2002 2
Type-5 AS External Link States
ADV Router Age Seq# Prefix
10.2.2.1 712 0x80000001 10.1.1.0/24
10.2.2.1 712 0x80000001 172.16.1.1/32
Verify that PE2 is receiving the prefix 172.16.1.1/32 as inter-area route because both PE routers are using their default domain ID which the process ID of OSPF:
PE2#show ospfv3 vrf CUST-B database
OSPFv3 1 address-family ipv4 vrf CUST-B (router-id 10.4.4.1)
Router Link States (Area 0)
ADV Router Age Seq# Fragment ID Link count Bits
10.4.4.1 983 0x80000005 0 1 B E
172.16.2.1 926 0x80000004 0 1 None
Net Link States (Area 0)
ADV Router Age Seq# Link ID Rtr count
172.16.2.1 926 0x80000003 2 2
Inter Area Prefix Link States (Area 0)
ADV Router Age Seq# Prefix
10.4.4.1 724 0x80000002 10.3.3.0/24
10.4.4.1 724 0x80000002 172.16.1.1/32
Link (Type-8) Link States (Area 0)
ADV Router Age Seq# Link ID Interface
10.4.4.1 983 0x80000003 3 Fa0/1
172.16.2.1 1179 0x80000003 2 Fa0/1
Intra Area Prefix Link States (Area 0)
ADV Router Age Seq# Link ID Ref-lstype Ref-LSID
172.16.2.1 926 0x80000005 0 0x2001 0
172.16.2.1 926 0x80000003 2048 0x2002 2
PE2#
Finally verify the routing tables of the CE routers:
CE-A1 and CE-A2 routers are receiving external routes O E2 from PE1 and PE2 routers respectively because the mismatched domain ID.
CE-B1 and CE-B2 routers are receiving inter-area routes O IA from PE1 and PE2 routers respectively because the matched domain ID.
CE-A1#show ip route OSPFv3 | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O E2 10.2.2.0/24 [110/1] via 10.1.1.1, 00:13:45, FastEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O E2 172.16.2.1/32 [110/1] via 10.1.1.1, 00:13:45, FastEthernet0/0
CE-A1#
CE-A2#show ip route ospfv3 | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O E2 10.1.1.0/24 [110/1] via 10.2.2.1, 00:15:06, FastEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O E2 172.16.1.1/32 [110/1] via 10.2.2.1, 00:15:06, FastEthernet0/0
CE-A2#
CE-B1#show ip route ospfv3 | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O IA 10.4.4.0/24 [110/2] via 10.3.3.1, 00:48:56, FastEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.16.2.1/32 [110/2] via 10.3.3.1, 00:48:56, FastEthernet0/0
CE-B1#
CE-B2#show ip route ospfv3 | beg Gate
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O IA 10.3.3.0/24 [110/2] via 10.4.4.1, 00:50:02, FastEthernet0/0
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
O IA 172.16.1.1/32 [110/2] via 10.4.4.1, 00:50:02, FastEthernet0/0
CE-B2#