166
In a hub and spoke network as shown in
, configure route targets as follows:
•
On spoke PEs (PEs connected to spoke sites), set the export target to Spoke and the import target to
Hub.
•
On the hub PE (PE connected to the hub site), use two interfaces that each belong to a different VPN
instance to connect the hub CE. One VPN instance receives routes from spoke PEs and has the
import target set to Spoke. The other VPN instance advertises routes to spoke PEs and has the export
target set to Hub.
These route targets rules produce the following results:
•
The hub PE can receive all VPN-IPv4 routes from spoke PEs.
•
All spoke PEs can receive VPN-IPv4 routes advertised by the hub PE.
•
The hub PE advertises the routes learned from a spoke PE to the other spoke PEs so the spoke sites
can communicate with each other through the hub site.
•
The import target attribute of a spoke PE is different from the export target attribute of any other
spoke PE. Therefore, any two spoke PEs cannot directly advertise VPN-IPv4 routes to each other or
directly access each other.
Figure 44
Network diagram for hub and spoke network
A route in Site 1 is advertised to Site 2 by using the following process:
1.
Spoke-CE 1 advertises a route in Site 1 to Spoke-PE 1.
2.
Spoke-PE 1 changes the route to a VPN-IPv4 route and advertises the VPN-IPv4 route to Hub-PE
through MP-BGP.
3.
Hub-PE adds the VPN-IPv4 route into the routing table of VPN 1-in, changes it to the original IPv4
route, and advertises the IPv4 route to Hub-CE.
4.
Hub-CE advertises the IPv4 route back to Hub-PE.
5.
Hub-PE adds the IPv4 route to the routing table of VPN 1-out, changes it to a VPN-IPv4 route, and
advertises the VPN-IPv4 route to Spoke-PE 2 through MP-BGP.
6.
Spoke-PE 2 changes the VPN-IPv4 route to the original IPv4 route, and advertises the IPv4 route to
Site 2.