R5

R2

Regional Hub

Lo0

172.16.44.1/24

Lo0

172.16.55.1/24

Logical Topology

Spoke Spoke

R4

Tu1

Tu1 Tu1 Tu1

Regional Domain

NHRP ID 1

192.168.1.0/24

GRE Key 1

.2

.4 .5

Dynamic Spoke-to-Spoke

IPSec/GRE IPSec/GRE

R3

R1

Central Hub

Regional Hub

Tu1

.3

Regional Domain

NHRP ID 1

192.168.2.0/24

GRE Key 1

Central Domain

NHRP ID 1

192.168.3.0/24

GRE Key 3

Tu3

Tu3

.2 .3

Tu3

.1

172.16.4.12/30

R1

R2 R4

R5

Physical Topology

172.16.4.0/30

172.16.4.4/30

172.16.4.8/30

172.16.4.16/30

.6.13

.9

.5

.1 .17

SW1

.2

.10

.14

.18

Fa0/0Fa0/0

Fa0/0

Fa0/0

Fa0/0

R3

IPSec/GRE IPSec/GRE

GRE Src 192.168.1.4 | Dst 192.168.2.5