In this Post , I am giving example of a complete MPLS Layer 3 Lab configuration using GNS3

Diagram:

Preliminary Task:

Connect the network as shown in the diagram, and assign the ip addresses as explained in the above figure.

Configure Loopback addresses for PE & P routers as follows: PE1: 1.1.1.1/32, PE2: 2.2.2.2/32, P1: 3.3.3.3/32 , P2:4.4.4.4/32

Task 1:

Configure two VRFs (CE_A & CE_B) on each of the PE routers, and put the PE-CE interfaces into the equivalent interfaces:

!PE1

ip vrf CE_A

rd 1:1

route-target both 1:1

!

ip vrf CE_B

rd 2:2

route-target both 2:2

!

int fa0/0

ip vrf forwarding CE_A

ip address 172.17.0.1 255.255.0.0

!

int fa0/1

ip vrf forwarding CE_B

ip address 172.19.0.1 255.255.0.0

!PE2

ip vrf CE_A

rd 1:1

route-target both 1:1

!

ip vrf CE_B

rd 2:2

route-target both 2:2

!

int fa0/0

ip vrf forwarding CE_A

ip address 172.21.0.1 255.255.0.0

!

int fa0/1

ip vrf forwarding CE_B

ip address 172.23.0.1 255.255.0.0

Task 2:

Configure OSPF 10 between the PE & CE routers and ensure the OSPF adjacencies have been established.

!CE_A1

router ospf 10

network 172.16.0.0 0.0.255.255 area 0

network 172.17.0.0 0.0.255.255 area 0

!CE_B1

router ospf 11

network 172.18.0.0 0.0.255.255 area 0

network 172.19.0.0 0.0.255.255 area 0

!PE1

router ospf 10 vrf CE_A

log-adjacency-changes

network 172.17.0.0 0.0.255.255 area 0

!

router ospf 11 vrf CE_B

log-adjacency-changes

network 172.19.0.0 0.0.255.255 area 0

!CE_A2

router ospf 10

network 172.20.0.0 0.0.255.255 area 0

network 172.21.0.0 0.0.255.255 area 0

!CE_B2

router ospf 11

network 172.22.0.0 0.0.255.255 area 0

network 172.23.0.0 0.0.255.255 area 0

!PE2

router ospf 10 vrf CE_A

log-adjacency-changes

network 172.21.0.0 0.0.255.255 area 0

!

router ospf 11 vrf CE_B

log-adjacency-changes

network 172.23.0.0 0.0.255.255 area 0

Task 3:

Configure OSPF process 1 between all the routers in the provider network and don't forget to include loopback interfaces advertisement.

!PE1

router ospf 1

network 1.1.1.1 0.0.0.0 area 0

network 192.168.1.0 0.0.0.255 area 0

network 192.168.2.0 0.0.0.255 area 0

!PE2

router ospf 1

network 2.2.2.2 0.0.0.0 area 0

network 192.168.3.0 0.0.0.255 area 0

network 192.168.4.0 0.0.0.255 area 0

!P1

router ospf 1

network 3.3.3.3 0.0.0.0 area 0

network 192.168.3.0 0.0.0.255 area 0

network 192.168.1.0 0.0.0.255 area 0

!P2

router ospf 1

network 4.4.4.4 0.0.0.0 area 0

network 192.168.2.0 0.0.0.255 area 0

network 192.168.4.0 0.0.0.255 area 0

Verification:

P1#show ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface

1.1.1.1 1 FULL/DR 00:00:34 192.168.1.2 FastEthernet1/0

2.2.2.2 1 FULL/BDR 00:00:34 192.168.3.1 FastEthernet1/1

P2#show ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface

2.2.2.2 1 FULL/DR 00:00:31 192.168.4.1 FastEthernet1/1

1.1.1.1 1 FULL/BDR 00:00:38 192.168.2.2 FastEthernet1/0

Task 4:

Configure BGP AS 100 between the PE routers, and use loopback interface as the update source.

!PE1

router bgp 100

no synchronization

bgp log-neighbor-changes

neighbor 2.2.2.2 remote-as 100

neighbor 2.2.2.2 update-source Loopback0

!PE2

router bgp 100

no synchronization

bgp log-neighbor-changes

neighbor 1.1.1.1 remote-as 100

neighbor 1.1.1.1 update-source Loopback0

Verification:

PE1#show ip bgp summary

BGP router identifier 1.1.1.1, local AS number 100 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 4 100 2 2 0 0 0 00:00:29 0

Task 5:

Activate MP-BGP neighborhood between the PE routers, in order to advertise the VRF customer routes later with their route distinguisher.

!PE1

router bgp 100

address-family vpnv4

neighbor 2.2.2.2 activate

neighbor 2.2.2.2 send-community extended

!

!PE2

router bgp 100

address-family vpnv4

neighbor 1.1.1.1 activate

neighbor 1.1.1.1 send-community extended

Verification:

PE1#show ip bgp vpnv4 all summary

BGP router identifier 1.1.1.1, local AS number 100 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 4 100 9 9 1 0 0 00:00:25 0

Task 6:

Redistribute Mutually between the OSPF and the BGP VPNv4 on PE1 & PE2:

!PE1/PE2

router bgp 100

address-family ipv4 vrf CE_A

redistribute ospf 10 vrf CE_A match internal external 1 external 2

address-family ipv4 vrf CE_B

redistribute ospf 11 vrf CE_B match internal external 1 external 2

!

router ospf 10 vrf CE_A

redistribute bgp 100 subnets

!

router ospf 11 vrf CE_B

redistribute bgp 100 subnets

Verification:

!CE_A1#show ip route

C 172.17.0.0/16 is directly connected, FastEthernet0/1 C 172.16.0.0/16 is directly connected, FastEthernet0/0

O IA 172.21.0.0/16 [110/2] via 172.17.0.1, 00:03:28, FastEthernet0/1

O IA 172.20.0.0/16 [110/3] via 172.17.0.1, 00:03:28, FastEthernet0/1

!CE_B1#show ip route

Gateway of last resort is not set

C 172.19.0.0/16 is directly connected, FastEthernet0/1 C 172.18.0.0/16 is directly connected, FastEthernet0/0

O IA 172.23.0.0/16 [110/2] via 172.19.0.1, 00:03:57, FastEthernet0/1

O IA 172.22.0.0/16 [110/3] via 172.19.0.1, 00:03:57, FastEthernet0/1

Task7:

Enable MPLS on all interfaces within the provider network

!PE1/PE2/P1/P2

int fa1/0

mpls ip

!

int fa1/1

mpls ip

Verification:

PE2#sh mpls ldp neighbor

Peer LDP Ident: 3.3.3.3:0; Local LDP Ident 2.2.2.2:0 TCP connection: 3.3.3.3.39927 - 2.2.2.2.646

State: Oper; Msgs sent/rcvd: 11/11; Downstream Up time: 00:00:45

LDP discovery sources:

FastEthernet1/0, Src IP addr: 192.168.3.2 Addresses bound to peer LDP Ident: 192.168.1.1 192.168.3.2 3.3.3.3

Peer LDP Ident: 4.4.4.4:0; Local LDP Ident 2.2.2.2:0 TCP connection: 4.4.4.4.20674 - 2.2.2.2.646

State: Oper; Msgs sent/rcvd: 11/11; Downstream Up time: 00:00:24

LDP discovery sources:

FastEthernet1/1, Src IP addr: 192.168.4.2 Addresses bound to peer LDP Ident: 192.168.2.1 192.168.4.2 4.4.4.4

PE1#show mpls ldp neighbor

Peer LDP Ident: 3.3.3.3:0; Local LDP Ident 1.1.1.1:0 TCP connection: 3.3.3.3.41239 - 1.1.1.1.646

State: Oper; Msgs sent/rcvd: 12/13; Downstream Up time: 00:01:40

LDP discovery sources:

FastEthernet1/0, Src IP addr: 192.168.1.1 Addresses bound to peer LDP Ident: 192.168.1.1 192.168.3.2 3.3.3.3

Peer LDP Ident: 4.4.4.4:0; Local LDP Ident 1.1.1.1:0 TCP connection: 4.4.4.4.60863 - 1.1.1.1.646

State: Oper; Msgs sent/rcvd: 12/12; Downstream Up time: 00:01:14

LDP discovery sources:

FastEthernet1/1, Src IP addr: 192.168.2.1 Addresses bound to peer LDP Ident: 192.168.2.1 192.168.4.2 4.4.4.4

PE1#show mpls forwarding-table

Local Outgoing Prefix Bytes Label Outgoing Next Hop Label Label or VC or Tunnel Id Switched interface

16 17 2.2.2.2/32 0 Fa1/0 192.168.1.1

17 2.2.2.2/32 0 Fa1/1 192.168.2.1

17 Pop Label 3.3.3.3/32 0 Fa1/0 192.168.1.1

18 Pop Label 4.4.4.4/32 0 Fa1/1 192.168.2.1

19 Pop Label 192.168.3.0/24 0 Fa1/0 192.168.1.1

20 Pop Label 192.168.4.0/24 0 Fa1/1 192.168.2.1

21 No Label 172.16.0.0/16[V] 0 Fa0/0 172.17.0.2

22 No Label 172.17.0.0/16[V] 0 aggregate/CE_A

23 No Label 172.18.0.0/16[V] 0 Fa0/1 172.19.0.2

24 No Label 172.19.0.0/16[V] 0 aggregate/CE_B

Ping Between PCs on CE_A should be working & on CE_B should be working as well.

Waleed Hashim Ali Adlan

CCIE#41999/HCIE#14518