Example for Applying a Route-Policy to Imported Routes

By applying route-policies, you can control the import of routes and set attributes for imported routes.

Networking Requirements

In Figure 1, Device A and Device B exchange routing information through OSPF; Device B and Device C exchange routing information through IS-IS.

It is required that Device B import IS-IS routes to OSPF and use the route-policy to set the cost of the route to 172.16.1.0/24 to 100 and set the tag of the route to 172.16.2.0/24 to 20.

Figure 1 Applying a route-policy to imported routes

Interfaces 1 through 4 in this example represent GE 0/1/0, GE 0/1/8, GE 0/1/16, and GE 0/1/1, respectively.

Precautions

When applying a route-policy to imported routes, note the following rules:

When configuring an IP prefix list, specify the IP prefix range as required.
The route-policy name is case sensitive.

Configuration Roadmap

The configuration roadmap is as follows:

Configure basic IS-IS functions on Device B and Device C.
Configure OSPF on Device A and Device B and import IS-IS routes.
Configure a routing policy on Device B, apply the route-policy when OSPF imports IS-IS routes, and check the routes.

Data Preparation

To complete the configuration, you need the following data:

Area IDs, IS-IS levels, and system IDs of Device B and Device C
Area 0 (backbone area), in which Device A and Device B are located
ACL number, name of the IP prefix list, cost of the route to 172.16.1.0/24, and tag of the route to 172.16.2.0/24

Procedure

Configure IP addresses for interfaces. For configuration details, see Configuration Files in this section.

Configure IS-IS.

# Configure Device C.

[~DeviceC] isis
[*DeviceC-isis-1] is-level level-2
[*DeviceC-isis-1] network-entity 10.0000.0000.0001.00
[*DeviceC-isis-1] quit
[*DeviceC] interface gigabitethernet 0/1/1
[*DeviceC-GigabitEthernet0/1/1] isis enable
[*DeviceC-GigabitEthernet0/1/1] quit
[*DeviceC] interface GigabitEthernet 0/1/0
[*DeviceC-GigabitEthernet0/1/0] isis enable
[*DeviceC-GigabitEthernet0/1/0] quit
[*DeviceC] interface GigabitEthernet 0/1/8
[*DeviceC-GigabitEthernet0/1/8] isis enable
[*DeviceC-GigabitEthernet0/1/8] quit
[*DeviceC] interface GigabitEthernet 0/1/16
[*DeviceC-GigabitEthernet0/1/16] isis enable
[*DeviceC-GigabitEthernet0/1/16] commit
[~DeviceC-GigabitEthernet0/1/16] quit

# Configure Device B.

[~DeviceB] isis
[*DeviceB-isis-1] is-level level-2
[*DeviceB-isis-1] network-entity 10.0000.0000.0002.00
[*DeviceB-isis-1] quit
[*DeviceB] interface gigabitethernet 0/1/8
[*DeviceB-GigabitEthernet0/1/8] isis enable
[*DeviceB-GigabitEthernet0/1/8] commit
[~DeviceB-GigabitEthernet0/1/8] quit

Configure OSPF and import routes.

# Configure Device A and enable OSPF.

[~DeviceA] ospf
[*DeviceA-ospf-1] area 0
[*DeviceA-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
[*DeviceA-ospf-1-area-0.0.0.0] commit
[~DeviceA-ospf-1-area-0.0.0.0] quit
[*DeviceA-ospf-1] quit

# Configure Device B, enable OSPF, and import IS-IS routes.

[~DeviceB] ospf
[*DeviceB-ospf-1] area 0
[*DeviceB-ospf-1-area-0.0.0.0] network 192.168.1.0 0.0.0.255
[*DeviceB-ospf-1-area-0.0.0.0] quit
[*DeviceB-ospf-1] import-route isis 1
[*DeviceB-ospf-1] commit
[~DeviceB-ospf-1] quit

# Check the IP routing table on Device A to view the imported routes.

[~DeviceA] display ospf routing
          OSPF 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
 172.16.1.0/24      1        Type2      1           192.168.1.2     192.168.1.2
 172.16.2.0/24      1        Type2      1           192.168.1.2     192.168.1.2
 172.16.3.0/24      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
 Routing for NSSAs
 Destination        Cost      Type       Tag         NextHop         AdvRouter
 Total Nets: 5
 Intra Area: 1  Inter Area: 0  ASE: 4  NSSA: 0

Configure filters.

# Configure an ACL numbered 2002 to import the route to 172.16.2.0/24.

[~DeviceB] acl number 2002
[*DeviceB-acl4-basic-2002] rule permit source 172.16.2.0 0.0.0.255
[*DeviceB-acl4-basic-2002] commit
[~DeviceB-acl4-basic-2002] quit

# Configure an IP prefix list named prefix-a to import the route to 172.16.1.0/24.

[~DeviceB] ip ip-prefix prefix-a index 10 permit 172.16.1.0 24
[*DeviceB] commit

Configure a route-policy.

[~DeviceB] route-policy isis2ospf permit node 10
[*DeviceB-route-policy] if-match ip-prefix prefix-a
[*DeviceB-route-policy] apply cost 100
[*DeviceB-route-policy] quit
[*DeviceB] route-policy isis2ospf permit node 20
[*DeviceB-route-policy] if-match acl 2002
[*DeviceB-route-policy] apply tag 20
[*DeviceB-route-policy] quit
[*DeviceB] route-policy isis2ospf permit node 30
[*DeviceB] commit
[~DeviceB-route-policy] quit

Apply the route-policy when routes are imported.

# Configure Device B and apply the route-policy when routes are imported.

[~DeviceB] ospf
[*DeviceB-ospf-1] import-route isis 1 route-policy isis2ospf
[*DeviceB-ospf-1] commit
[~DeviceB-ospf-1] quit

# Check the OSPF routing table on Device A. The command output shows that the cost of the route to 172.16.1.0/24 is 100, the tag of the route to 172.16.2.0/24 is 20, and that other route attributes remain unchanged.

[~DeviceA] display ospf routing
          OSPF 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
 172.16.1.0/24      100       Type2      1           192.168.1.2     192.168.1.2
 172.16.2.0/24      1          Type2      20          192.168.1.2     192.168.1.2
 172.16.3.0/24      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
 Routing for NSSAs
 Destination        Cost      Type       Tag         NextHop         AdvRouter
 Total Nets: 5
 Intra Area: 1  Inter Area: 0  ASE: 4  NSSA: 0

Configuration Files

Device A configuration file

#
 sysname DeviceA
#
interface GigabitEthernet0/1/0
 undo shutdown
 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

Device B configuration file

#
sysname DeviceB
#
acl number 2002
 rule 5 permit source 172.16.2.0 0.0.0.255
#
isis 1
 is-level level-2
 network-entity 10.0000.0000.0002.00
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 192.168.1.2 255.255.255.0
#
interface GigabitEthernet0/1/8
 undo shutdown
 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 172.16.1.0 24
#
return

Device C configuration file

#
sysname DeviceC
#
isis 1
 is-level level-2
 network-entity 10.0000.0000.0001.00
#
interface GigabitEthernet0/1/0
 undo shutdown
 ip address 172.16.1.1 255.255.255.0
 isis enable 1
#
interface GigabitEthernet0/1/8
 undo shutdown
 ip address 172.16.2.1 255.255.255.0
 isis enable 1
#
interface GigabitEthernet0/1/16
 undo shutdown
 ip address 172.16.3.1 255.255.255.0
 isis enable 1
#
interface GigabitEthernet0/1/1
 ip address 192.168.2.1 255.255.255.0
 isis enable 1
#
return