Example for Applying a Routing Policy for Importing Routes
Networking Requirements
In Figure 10-5, Router B exchanges routing information with Router A through OSPF, and with Router C through IS-IS. A user wants Router B to import IS-IS routes into the OSPF network. The user also wants the route to 172.17.1.0/24 on the OSPF network to have a low preference and the route to 172.17.2.0/24 to have a tag, making it easy to reference by a routing policy.
Configuration Roadmap
The configuration roadmap is as follows:
Configure a routing policy on Router B, set the cost of the route to 172.17.1.0/24 to 100, and apply the routing policy when OSPF imports IS-IS routes. The routing policy allows the route to 172.17.1.0/24 to have a low preference.
Configure a routing policy on Router B, set the tag of the route to 172.17.2.0/24 to 20, and apply the routing policy when OSPF imports IS-IS routes. This allows the tag of the route to 172.17.2.0/24 to take effect, making it easy to reference by a routing policy.
Procedure
- Assign an IP address to each interface.
# Configure IP addresses for all interfaces of RouterA.
<Huawei> system-view [Huawei] sysname RouterA [RouterA] interface gigabitethernet 1/0/0 [RouterA-GigabitEthernet1/0/0] ip address 192.168.1.1 255.255.255.0 [RouterA-GigabitEthernet1/0/0] quit
The configurations of RouterB and RouterC are similar to the configuration of RouterA, and are not mentioned here.
- Configure IS-IS.
# Configure Router C.
[RouterC] isis[RouterC-isis-1] is-level level-2[RouterC-isis-1] network-entity 10.0000.0000.0001.00[RouterC-isis-1] quit[RouterC] interface gigabitethernet 4/0/0[RouterC-GigabitEthernet4/0/0] isis enable[RouterC-GigabitEthernet4/0/0] quit[RouterC] interface gigabitethernet 1/0/0[RouterC-GigabitEthernet1/0/0] isis enable[RouterC-GigabitEthernet1/0/0] quit[RouterC] interface gigabitethernet 2/0/0[RouterC-GigabitEthernet2/0/0] isis enable[RouterC-GigabitEthernet2/0/0] quit[RouterC] interface gigabitethernet 3/0/0[RouterC-GigabitEthernet3/0/0] isis enable[RouterC-GigabitEthernet3/0/0] quit# Configure Router B.
[RouterB] isis[RouterB-isis-1] is-level level-2[RouterB-isis-1] network-entity 10.0000.0000.0002.00[RouterB-isis-1] quit[RouterB] interface gigabitethernet 2/0/0[RouterB-GigabitEthernet2/0/0] isis enable[RouterB-GigabitEthernet2/0/0] quit - Configure OSPF and import routes.
# Configure RouterA and enable OSPF.
[RouterA] ospf[RouterA-ospf-1] area 0[RouterA-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255[RouterA-ospf-1-area-0.0.0.0] quit[RouterA-ospf-1] quit# Configure RouterB. Enable OSPF and import IS-IS routes.
[RouterB] ospf[RouterB-ospf-1] area 0[RouterB-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255[RouterB-ospf-1-area-0.0.0.0] quit[RouterB-ospf-1] import-route isis 1[RouterB-ospf-1] quit# Check the OSPF routing table of RouterA. You can see the imported routes.
[RouterA] display ospf routingOSPF Process 1 with Router ID 192.168.1.1
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
192.168.1.0/24 1 Stub 192.168.1.1 192.168.1.1 0.0.0.0
Routing for ASEs
Destination Cost Type Tag NextHop AdvRouter
172.17.1.0/24 1 Type2 1 192.168.1.2 192.168.1.2
172.17.2.0/24 1 Type2 1 192.168.1.2 192.168.1.2
172.17.3.0/24 1 Type2 1 192.168.1.2 192.168.1.2
192.168.2.0/24 1 Type2 1 192.168.1.2 192.168.1.2
Total Nets: 5
Intra Area: 1 Inter Area: 0 ASE: 4 NSSA: 0
- Configure the filtering list.
# Configure ACL 2002 to match 172.17.2.0/24.
[RouterB] acl number 2002[RouterB-acl-basic-2002] rule permit source 172.17.2.0 0.0.0.255[RouterB-acl-basic-2002] quit# Configure the IP prefix list named prefix-a to match 172.17.1.0/24.
[RouterB] ip ip-prefix prefix-a index 10 permit 172.17.1.0 24 - Configure the route-policy.
[RouterB] route-policy isis2ospf permit node 10[RouterB-route-policy] if-match ip-prefix prefix-a[RouterB-route-policy] apply cost 100[RouterB-route-policy] quit[RouterB] route-policy isis2ospf permit node 20[RouterB-route-policy] if-match acl 2002[RouterB-route-policy] apply tag 20[RouterB-route-policy] quit[RouterB] route-policy isis2ospf permit node 30[RouterB-route-policy] quit - Apply the route-policy when the route is imported.
# Configure Router B and apply the route-policy when the route is imported.
[RouterB] ospf[RouterB-ospf-1] import-route isis 1 route-policy isis2ospf[RouterB-ospf-1] quit# Check the OSPF routing table of Router A. You can see that the cost of the route with the destination address 172.17.1.0/24 is 100; the tag of the route with the destination address 172.17.2.0/24 is 20; other routing attributes remain unchanged.
[RouterA] display ospf routingOSPF Process 1 with Router ID 192.168.1.1
Routing Tables
Routing for Network
Destination Cost Type NextHop AdvRouter Area
192.168.1.0/24 1 Stub 192.168.1.1 192.168.1.1 0.0.0.0
Routing for ASEs
Destination Cost Type Tag NextHop AdvRouter
172.17.1.0/24 100 Type2 1 192.168.1.2 192.168.1.2
172.17.2.0/24 1 Type2 20 192.168.1.2 192.168.1.2
172.17.3.0/24 1 Type2 1 192.168.1.2 192.168.1.2
192.168.2.0/24 1 Type2 1 192.168.1.2 192.168.1.2
Total Nets: 5
Intra Area: 1 Inter Area: 0 ASE: 4 NSSA: 0
Configuration Files
Configuration file of RouterA
#
sysname RouterA#
interface GigabitEthernet1/0/0
ip address 192.168.1.1 255.255.255.0
#
ospf 1
area 0.0.0.0
network 192.168.1.0 0.0.0.255
#
return
Configuration file of RouterB
#
sysname RouterB#
acl number 2002
rule 5 permit source 172.17.2.0 0.0.0.255
#
isis 1
is-level level-2
network-entity 10.0000.0000.0002.00
#
interface GigabitEthernet1/0/0
ip address 192.168.1.2 255.255.255.0
#
interface GigabitEthernet2/0/0
ip address 192.168.2.2 255.255.255.0
isis enable 1
#
ospf 1
import-route isis 1 route-policy isis2ospf
area 0.0.0.0
network 192.168.1.0 0.0.0.255
#
route-policy isis2ospf permit node 10
if-match ip-prefix prefix-a
apply cost 100
#
route-policy isis2ospf permit node 20
if-match acl 2002
apply tag 20
#
route-policy isis2ospf permit node 30
#
ip ip-prefix prefix-a index 10 permit 172.17.1.0 24
#
return
Configuration file of RouterC
#
sysname RouterC#
isis 1
is-level level-2
network-entity 10.0000.0000.0001.00
#
interface GigabitEthernet1/0/0
ip address 172.17.1.1 255.255.255.0
isis enable 1
#
interface GigabitEthernet2/0/0
ip address 172.17.2.1 255.255.255.0
isis enable 1
#
interface GigabitEthernet3/0/0
ip address 172.17.3.1 255.255.255.0
isis enable 1
#
interface GigabitEthernet4/0/0
ip address 192.168.2.1 255.255.255.0
isis enable 1
#
return
