Information Technology Reference
In-Depth Information
When a VPNv4 route is being imported, it is evaluated sequentially, first by the RT import
policy (configured with the command
route-target import
) and then by the import map
(configured with the command
import map
) if it's configured. For a route to be imported,
it must pass both policies. If no RT import policy is configured, all routes are denied, even
if they are permitted later by the import map policy. If no import map is configured, routes
are imported based on the RT import policy.
NOTE
On a customer VPN, routes with proper RTs must be exported. Example 10-46 shows a
sample configuration. An export map Cust1_out is configured. If an address matches
CE1, set an RT of 100:2001 (to be imported into the management VRF); if not, set an RT
of 100:200 (to be imported into Cust1 VPN). The management RT 100:2000 is imported
into each customer VRF. Additional filtering can be configured to permit only the manage-
ment stations.
Example 10-46
Customer VPNs for Management
ip vrf Cust1
rd 100:200
export map Cust1_out
route-target import 100:200
route-target import 100:2000
!
ip prefix-list CE1 seq 5 permit 192.168.100.1/32
!
route-map Cust1_out permit 10
match ip address prefix-list CE1
set extcommunity rt 100:2001
!
route-map Cust1_out permit 20
set extcommunity rt 100:200
NOTE
Unlike the import map, the export map performs no RT filtering function. If both the RT
export and export map are configured, the export map takes precedence in setting the
RT values. In fact, there is no need to configure an RT export if an export map is configured.
If both policies are required, the keyword
additive
can be used in the export map's set
clause.
Convergence
Convergence
is the time it takes for routers in a routing domain to learn the complete
topology and to recompute alternative paths to a particular destination after a network
