Case Study—Hub and Spoke MPLS VPN Network with Sites Using Same AS Numbers

Figure 6-24 shows the relevant configuration for a similar MPLS VPN network as shown in the previous case study except that spoke sites now use the same BGP AS as configured on CE1-A (AS 65001). In this case study, because sites are using the same BGP AS number, the neighbor as-override command is used.

Figure 6-24. Hub and Spoke MPLS VPN Network with Sites Using Same AS Numbers

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Verifying MPLS VPN Hub and Spoke Routing for Spoke Sites Using Same AS Numbers

The steps to verify MPLS VPN hub and spoke routing for spoke sites using the same AS numbers are

CE1-A#show ip route bgp

     172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks

B       172.16.30.0/24 [20/0] via 172.16.1.1, 00:08:42

B       172.16.20.0/24 [20/0] via 172.16.1.1, 00:08:42

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CE1-A#show ip bgp

<truncated for brevity>

   Network        Next Hop           Metric LocPrf Weight Path

*> 172.16.10.0/24 0.0.0.0                 0         32768 i

*> 172.16.20.0/24 172.16.1.1                            0 1 1 i

*> 172.16.30.0/24 172.16.1.1                            0 1 1 i

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CE2-A#show ip route bgp

     172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks

B       172.16.30.0/24 [20/0] via 172.16.2.1, 00:08:39

B       172.16.10.0/24 [20/0] via 172.16.2.1, 00:12:02

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CE2-A#show ip bgp

   Network        Next Hop          Metric LocPrf Weight Path

*> 172.16.10.0/24 172.16.2.1                           0 1 1 i

*> 172.16.20.0/24 0.0.0.0                0         32768 i

*> 172.16.30.0/24 172.16.2.1                           0 1 1 1 1 i

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CE3-A#sh ip route bgp

     172.16.0.0/16 is variably subnetted, 4 subnets, 2 masks

B       172.16.20.0/24 [20/0] via 172.16.3.1, 00:09:23

B       172.16.10.0/24 [20/0] via 172.16.3.1, 00:11:59

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CE3-A#show ip bgp

<truncated for brevity>

   Network        Next Hop           Metric LocPrf Weight Path

*> 172.16.10.0/24 172.16.3.1                            0 1 1 i

*> 172.16.20.0/24 172.16.3.1                            0 1 1 1 1 i

*> 172.16.30.0/24 0.0.0.0                 0         32768 i

CE2-A#ping 172.16.30.1 source 172.16.20.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.30.1, timeout is 2 seconds:

Packet sent with a source address of 172.16.20.1

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 120/120/124 ms

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CE2-A#ping 172.16.10.1 source 172.16.20.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.10.1, timeout is 2 seconds:

Packet sent with a source address of 172.16.20.1

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 60/61/68 ms

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CE3-A#ping 172.16.20.1 source 172.16.30.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.20.1, timeout is 2 seconds:

Packet sent with a source address of 172.16.30.1

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 116/119/120 ms

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CE3-A#ping 172.16.10.1 source 172.16.30.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.16.10.1, timeout is 2 seconds:

Packet sent with a source address of 172.16.30.1

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 60/62/72 ms