Rate and give feedback:  Feedback Received. Thank You!

Rate and give feedback: 

X

This document helped resolve my issue

Yes No

Additional Comments

800 characters remaining

May we contact you if necessary?

Name:  

E-mail: 

Enter a valid Email ID

Need product assistance? Contact Juniper Support

Submit

This site is protected by hCaptcha and its Privacy Policy and Terms of Service apply.

English  

English

Examples: Configuring Routing Policy for Network Summaries

Import and Export Policies for Network Summaries Overview

By default, OSPF uses network-summary link-state advertisements (LSAs) to transmit route information across area boundaries. Each area border router (ABR) floods network-summary LSAs to other routing devices in the same area. The ABR also controls which routes from the area are used to generate network-summary LSAs into other areas. Each ABR maintains a separate topological database for each area to which they are connected. In Junos OS Release 9.1 and later, you can configure export and import policies for OSPFv2 and OSPFv3 that enable you to control how network-summary LSAs, which contain information about interarea OSPF prefixes, are distributed and generated. For OSPFv3, the LSA is referred to as the interarea prefix LSA and performs the same function as a network-summary LSA performs for OSPFv2. An ABR originates an interarea prefix LSA for each IPv6 prefix that must be advertised into an area.

The export policy enables you to specify which summary LSAs are flooded into an area. The import policy enables you to control which routes learned from an area are used to generate summary LSAs into other areas. You define a routing policy at the [edit policy-options policy-statement policy-name] hierarchy level. As with all OSPF export policies, the default for network-summary LSA export policies is to reject everything. Similarly, as with all OSPF import policies, the default for network-summary LSA import policies is to accept all OSPF routes.

Example: Configuring an OSPF Export Policy for Network Summaries

This example shows how to create an OSPF export policy to control the network-summary (Type 3) LSAs that the ABR floods into an OSPF area.

• Requirements
• Overview
• Configuration
• Verification

Requirements

• Configure the router identifiers for the devices in your OSPF network. See Example: Configuring an OSPF Router Identifier.
• Control OSPF designated router election. See Example: Controlling OSPF Designated Router Election

Overview

OSPF uses network-summary LSAs to transmit route information across area boundaries. Depending on your network environment, you might want to further filter the network-summary LSAs between OSPF areas. For example, if you create OSPF areas to define administrative boundaries, you might not want to advertise internal route information between those areas. To further improve the control of route distribution between multiple OSPF areas, you can configure network summary policies on the ABR for the area that you want to filter the advertisement of network-summary LSAs.

Note: For OSPFv3, the LSA is referred to as the interarea prefix LSA and performs the same function as a network-summary LSA performs for OSPFv2. An ABR originates an interarea prefix LSA for each IPv6 prefix that must be advertised into an area. In this topic, the terms network summary policy and network-summary policy are used to describe both OSPFv2 and OSPFv3 functionality.

• You should have a thorough understanding of your network before configuring these policies. Incorrect network summary policy configuration might result in an unintended result such as suboptimal routing or dropped traffic.
• We recommend that you use the route-filter policy match condition for these types of policies.
• We recommend that you use the accept and reject routing policy terms for these types of policies.

Figure 1 shows a sample topology with three OSPF areas. R4 generates network summaries for the routes in area 4 and sends them out of area 4 to area 0. R3 generates network summaries for the routes in area 3 and sends them out of area 3 to area 0.

Figure 1: Sample Topology Used for an OSPF Export Network Summary Policy

In this example, you configure R4 with an export network summary policy named export-policy that only allows routes that match the 10.0.4.4 prefix from area 3 into area 4. The export policy controls the network-summary LSAs that R4 floods into area 4. This results in only the allowed interarea route to enter area 4, and all other interarea routes to be purged from the OSPF database and the routing table of the devices in area 4. You first define the policy and then apply it to the ABR by including the network-summary-export statement for OSPFv2 or the inter-area-prefix-export statement for OSPFv3.

• R1—Device R1 is an internal router in area 3. Interface fe-0/1/0 has an IP address of 10.0.4.13/30 and connects to R3. Interface fe-0/0/1 has an IP address of 10.0.4.5/30 and connects to R2.
• R2—Device R2 is an internal router in area 3. Interface fe-0/0/1 has an IP address of 10.0.4.6/30 and connects to R1. Interface fe-1/0/0 has an IP address of 10.0.4.1 and connects to R3.
• R3—Device R3 participates in area 3 and area 0. R3 is the ABR between area 3 and area 0, and passes network-summary LSAs between the areas. Interface fe-1/0/0 has an IP address of 10.0.4.2/30 and connects to R2. Interface fe-1/1/0 has an IP address of 10.0.4.14/30 and connects to R1. Interface fe-0/0/1 has an IP address of 10.0.2.1/30 and connects to R4.
• R4—Device R4 participates in area 0 and area 4. R4 is the ABR between area 0 and area 4, and passes network-summary LSAs between the areas. Interface fe-0/0/1 has an IP address of 10.0.2.4/30 and connects to R3. Interface fe-1/1/0 has an IP address of 10.0.8.6/30 and connects to R5. Interface fe-1/0/0 has an IP address of 10.0.8.9/30 and connects to R6.
• R5—Device R5 is an internal router in area 4. Interface fe-1/1/0 has an IP address of 10.0.8.5/30 and connects to R4.
• R6—Device R6 is an internal router in area 4. Interface fe-1/0/0 has an IP address of 10.0.8.10/30 and connects to R4.

Configuration

CLI Quick Configuration

To quickly configure an OSPF export policy for network summaries, copy the following commands, removing any line breaks, and then paste the commands into the CLI.

Configuration on Device R1:

Configuration on Device R2:

Configuration on Device R3:

Configuration on Device R4:

Configuration on Device R5:

Configuration on Device R6:

Step-by-Step Procedure

1. Configure the interfaces.

   Note: For OSPFv3, use IPv6 addresses.

   [edit]user@R1# set interfaces fe-0/1/0 unit 0 family inet address 10.0.4.13/30user@R1# set interfaces fe-0/0/1 unit 0 family inet address 10.0.4.5/30
   [edit]user@R2# set interfaces fe-0/1/0 unit 0 family inet address 10.0.4.6/30user@R2# set interfaces fe-1/0/0 unit 0 family inet address 10.0.4.1/30
   [edit]user@R3# set interfaces fe-1/0/0 unit 0 family inet address 10.0.4.2/30user@R3# set interfaces fe-1/1/0 unit 0 family inet address 10.0.4.14/30user@R3#set interfaces fe-0/0/1 unit 0 family inet address 10.0.2.1/30
   [edit]user@R4# set interfaces fe-0/0/1 unit 0 family inet address 10.0.2.1/30user@R4# set interfaces fe-1/1/0 unit 0 family inet address 10.0.8.6/30user@R4# set interfaces fe-1/0/0 unit 0 family inet address 10.0.8.9/30
   [edit]user@R5# set interfaces fe-1/1/0 unit 0 family inet address 10.0.8.5/30
   [edit]user@R6# set interfaces fe-1/0/0 unit 0 family inet address 10.0.8.10/30
2. Enable OSPF on the interfaces.

   Note: For OSPFv3, include the ospf3 statement at the [edit protocols] hierarchy level.

   [edit]user@R1# set protocols ospf area 0.0.0.3 interface fe-0/1/0user@R1# set protocols ospf area 0.0.0.3 interface fe-0/0/1
   [edit]user@R2# set protocols ospf area 0.0.0.3 interface fe-0/1/0user@R2# set protocols ospf area 0.0.0.3 interface fe-1/0/0
   [edit]user@R3# set protocols ospf area 0.0.0.3 interface fe-1/0/0user@R3# set protocols ospf area 0.0.0.3 interface fe-1/1/0user@R3# set protocols ospf area 0.0.0.0 interface fe-0/0/1
   [edit]user@R4# set protocols ospf area 0.0.0.0 interface fe-0/0/1user@R4# set protocols ospf area 0.0.0.4 interface fe-1/1/0user@R4# set protocols ospf area 0.0.0.4 interface fe-1/0/0
   [edit]user@R5# set protocols ospf area 0.0.0.4 interface fe-1/1/0
   [edit]user@R6# set protocols ospf area 0.0.0.4 interface fe-1/0/0
3. On R4, configure the export network summary policy.
   [edit ]user@R4# set policy-options policy-statement export-policy term term1 from route-filter 10.0.4.4/30 prefix-length-range /30-/30 user@R4# set policy-options policy-statement export-policy term term1 then accept
4. On R4, apply the export network summary policy to OSPF.

   Note: For OSPFv3, include the inter-area-prefix-export statement at the [edit protocols ospf3 area area-id] hierarchy level.

   [edit]user@R4# set protocols ospf area 0.0.0.4 network-summary-export export-policy
5. If you are done configuring the devices, commit the configuration.
   [edit]user@host# commit

Results

Confirm your configuration by entering the show interfaces, show policy-options, and show protocols ospf commands on the appropriate device. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

Output for R1:

Output for R2:

Output for R3:

Output for R4:

Output for R5:

Output for R6:

To confirm your OSPFv3 configuration, enter the show interfaces, show policy-options, and show protocols ospf3 commands on the appropriate device.

Verification

Confirm that the configuration is working properly.

• Verifying the OSPF Database
• Verifying the Routing Table

Verifying the OSPF Database

Purpose

Verify that the OSPF database for the devices in area 4 includes the interarea route that we permitted on the ABR R4. The other interarea routes that are not specified should age out or no longer be present in the OSPF database.

Action

From operational mode, enter the show ospf database netsummary area 0.0.0.4 command for OSPFv2, and enter the show ospf3 database inter-area-prefix area 0.0.0.4 command for OSPFv3.

Verifying the Routing Table

Purpose

Verify that the routes corresponding to the rejected network summaries are no longer present in R4’s, R5’s, or R6’s routing table.

Action

From operational mode, enter the show route protocol ospf command for both OSPFv2 and OSPFv3.

Example: Configuring an OSPF Import Policy for Network Summaries

This example shows how to create an OSPF import policy to control the network-summary (Type 3) LSAs that the ABR advertises out of an OSPF area.

• Requirements
• Overview
• Configuration
• Verification

Requirements

• Configure the router identifiers for the devices in your OSPF network. See Example: Configuring an OSPF Router Identifier.
• Control OSPF designated router election. See Example: Controlling OSPF Designated Router Election.

Overview

OSPF uses network-summary LSAs to transmit route information across area boundaries. Depending on your network environment, you might want to further filter the network-summary LSAs between OSPF areas. For example, if you create OSPF areas to define administrative boundaries, you might not want to advertise internal route information between those areas. To further improve the control of route distribution between multiple OSPF areas, you can configure network summary policies on the ABR for the area that you want to filter the advertisement of network-summary LSAs.

Note: For OSPFv3, the LSA is referred to as the interarea prefix LSA and performs the same function as a network-summary LSA performs for OSPFv2. An ABR originates an interarea prefix LSA for each IPv6 prefix that must be advertised into an area. In this topic, the terms network summary policy and network-summary policy are used to describe both OSPFv2 and OSPFv3 functionality.

• You should have a thorough understanding of your network before configuring these policies. Incorrect network summary policy configuration might result in an unintended result such as suboptimal routing or dropped traffic.
• We recommend that you use the route-filter policy match condition for these types of policies.
• We recommend that you use the accept and reject routing policy terms for these types of policies.

Figure 2 shows a sample topology with three OSPF areas. R4 generates network summaries for the routes in area 4 and sends them out of area 4 to area 0. R3 generates network summaries for the routes in area 3 and sends them out of area 3 to area 0.

Figure 2: Sample Topology Used for an OSPF Import Network Summary Policy

In this example, you configure R3 with an import network summary policy named import-policy so R3 only generates network summaries for the route 10.0.4.12/30. The import policy controls the routes and therefore the network summaries that R3 advertises out of area 3, so applying this policy means that R3 only advertises route 10.0.4.12/30 out of area 3. This results in existing network summaries from other interarea routes getting purged from the OSPF database in area 0 and area 4, as well as the routing tables of the devices in areas 0 and area 4. You first define the policy and then apply it to the ABR by including the network-summary-import statement for OSPFv2 or the inter-area-prefix-import statement for OSPFv3.

• R1—Device R1 is an internal router in area 3. Interface fe-0/1/0 has an IP address of 10.0.4.13/30 and connects to R3. Interface fe-0/0/1 has an IP address of 10.0.4.5/30 and connects to R2.
• R2—Device R2 is an internal router in area 3. Interface fe-0/0/1 has an IP address of 10.0.4.6/30 and connects to R1. Interface fe-1/0/0 has an IP address of 10.0.4.1/30 and connects to R3.
• R3—Device R3 participates in area 3 and area 0. R3 is the ABR between area 3 and area 0, and passes network-summary LSAs between the areas. Interface fe-1/0/0 has an IP address of 10.0.4.2/30 and connects to R2. Interface fe-1/1/0 has an IP address of 10.0.4.14/30 and connects to R1. Interface fe-0/0/1 has an IP address of 10.0.2.1/30 and connects to R4.
• R4—Device R4 participates in area 0 and area 4. R4 is the ABR between area 0 and area 4, and passes network-summary LSAs between the areas. Interface fe-0/0/1 has an IP address of 10.0.2.1/30 and connects to R3. Interface fe-1/1/0 has an IP address of 10.0.8.6/30 and connects to R5. Interface fe-1/0/0 has an IP address of 10.0.8.9/30 and connects to R6.
• R5—Device R5 is an internal router in area 4. Interface fe-1/1/0 has an IP address of 10.0.8.5/30 and connects to R4.
• R6—Device R6 is an internal router in area 4. Interface fe-1/0/0 has an IP address of 10.0.8.10/30 and connects to R4.

Configuration

CLI Quick Configuration

To quickly configure an OSPF import policy for network summaries, copy the following commands, removing any line breaks, and then paste the commands into CLI.

Configuration on Device R1:

Configuration on Device R2:

Configuration on Device R3:

Configuration on Device R4:

Configuration on Device R5:

Configuration on Device R6:

Step-by-Step Procedure

1. Configure the interfaces.

   Note: For OSPFv3, use IPv6 addresses.

   [edit]user@R1# set interfaces fe-0/1/0 unit 0 family inet address 10.0.4.13/30user@R1# set interfaces fe-0/0/1 unit 0 family inet address 10.0.4.5/30
   [edit]user@R2# set interfaces fe-0/1/0 unit 0 family inet address 10.0.4.6/30user@R2# set interfaces fe-1/0/0 unit 0 family inet address 10.0.4.1/30
   [edit]user@R3# set interfaces fe-1/0/0 unit 0 family inet address 10.0.4.2/30user@R3# set interfaces fe-1/1/0 unit 0 family inet address 10.0.4.14/30user@R3#set interfaces fe-0/0/1 unit 0 family inet address 10.0.2.1/30
   [edit]user@R4# set interfaces fe-0/0/1 unit 0 family inet address 10.0.2.1/30user@R4# set interfaces fe-1/1/0 unit 0 family inet address 10.0.8.6/30user@R4# set interfaces fe-1/0/0 unit 0 family inet address 10.0.8.9/30
   [edit]user@R5# set interfaces fe-1/1/0 unit 0 family inet address 10.0.8.5/30
   [edit]user@R6# set interfaces fe-1/0/0 unit 0 family inet address 10.0.8.10/30
2. Enable OSPF on the interfaces.

   Note: For OSPFv3, include the ospf3 statement at the [edit protocols] hierarchy level.

   [edit]user@R1# set protocols ospf area 0.0.0.3 interface fe-0/1/0user@R1# set protocols ospf area 0.0.0.3 interface fe-0/0/1
   [edit]user@R2# set protocols ospf area 0.0.0.3 interface fe-0/1/0user@R2# set protocols ospf area 0.0.0.3 interface fe-1/0/0
   [edit]user@R3# set protocols ospf area 0.0.0.3 interface fe-1/0/0user@R3# set protocols ospf area 0.0.0.3 interface fe-1/1/0user@R3# set protocols ospf area 0.0.0.0 interface fe-0/0/1
   [edit]user@R4# set protocols ospf area 0.0.0.0 interface fe-0/0/1user@R4# set protocols ospf area 0.0.0.4 interface fe-1/1/0user@R4# set protocols ospf area 0.0.0.4 interface fe-1/0/0
   [edit]user@R5# set protocols ospf area 0.0.0.4 interface fe-1/1/0
   [edit]user@R6# set protocols ospf area 0.0.0.4 interface fe-1/0/0
3. On R3, configure the import network summary policy.
   [edit ]user@R3# set policy-options policy-statement import-policy term term1 from route-filter 10.0.4.12/30 prefix-length-range /30-/30 user@R3# set policy-options policy-statement export-policy term term1 then accept
4. On R3, apply the import network summary policy to OSPF.

   Note: For OSPFv3, include the inter-area-prefix-export statement at the [edit protocols ospf3 area area-id] hierarchy level.

   [edit]user@R3# set protocols ospf area 0.0.0.4 network-summary-import import-policy
5. If you are done configuring the devices, commit the configuration.
   [edit]user@host# commit

Results

Confirm your configuration by entering the show interfaces, show policy-options, and show protocols ospf commands on the appropriate device. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.

Output for R1:

Output for R2:

Output for R3:

Output for R4:

Output for R5:

Output for R6:

To confirm your OSPFv3 configuration, enter the show interfaces, show policy-options, and show protocols ospf3 commands on the appropriate device.

Verification

Confirm that the configuration is working properly.

• Verifying the OSPF Database
• Verifying the Routing Table

Verifying the OSPF Database

Purpose

Verify that the OSPF database for the devices in area 4 includes the interarea route that we are advertising from R3. Any other routes from area 3 should not be advertised into area 4, so those entries should age out or no longer be present in the OSPF database.

Action

From operational mode, enter the show ospf database netsummary area 0.0.0.4 command for OSPFv2, and enter the show ospf3 database inter-area-prefix area 0.0.0.4 command for OSPFv3.

Verifying the Routing Table

Purpose

Verify that the specified route is included in R4’s, R5’s, or R6’s routing table. Any other routes from area 3 should not be advertised into area 4.

Action

From operational mode, enter the show route protocol ospf command for both OSPFv2 and OSPFv3.