Chapter 1. MP-BGP Setup

This chapter contains the following content:

- Set Up the MP-BGP Route Reflector

Set Up the MP-BGP Route Reflector

This section shows an example of Infra MP-BGP configuration within each pod. This set up is a prerequisite to use any Cisco ACI L3Out configurations. All the examples in this document assume the Infra MP-BGP is configured.

Note

See the Cisco ACI Multi-Pod White Paper for more details about Infra MP-BGP between each pod (called external MP-BGP between spine switches).

Example Topology of Infra MP-BGP in Multi-Pod Setup

The preceding topology diagram displays an example where Cisco ACI is configured with infra MP-BGP AS number 65001 along with two route reflector spine switches in each pod. Infra MP-BGP sessions are established within each pod between the spine switches and the leaf switches. Leaf switches in each pod do not peer with route reflector spine switches in other pods. The following diagram explains how to configure the MP-BGP route reflector in this example.

Diagram of the MP-BGP Route Reflector Configuration

First, configure the AS number 65001 as Cisco ACI infra MP-BGP which is used for all the pods. Next, specify the spine switches to be the route reflector in each pod as follows:

- Pod 1 node: 1001, 1002

- Pod 2: node 2001, 2002.

Note

In this example, all spine switches are configured as route reflectors. However, if you have more than two spine switches per pod, not all spine switches are required to be configured as route reflectors. It is recommended to have two route reflector spine switches per pod.

For Policy Group name, in this example we use PodPG. In your example, you can use any name that you chooose. However, for the BGP Route Reflector policy, we choose the default policy, and you must use the default policy. Next, assign the default policy to the pod policy group and the PodPG to the pod profile as displayed in the preceding Figure.

Further details are displayed in the following related screenshots:

BGP Route Reflector Policy Example in Cisco APIC GUI

Pod Profile and Policy Group for BGP Route Reflector in Cisco APIC GUI

For more details, see the information about MP-BGP route reflectors at the following URLs:

- Cisco APIC Layer 3 Networking Configuration Guide

https://www.cisco.com/c/en/us/support/cloud-systems-management/application-policy-infrastructure-controller-apic/tsd-products-support-series-home.html

- Cisco ACI Fabric L3Out Guide

https://www.cisco.com/c/en/us/solutions/collateral/data-center-virtualization/application-centric-infrastructure/guide-c07-743150.html

Chapter 2. Example 1 - An OSPF L3Out With Two External Routers

This chapter includes the following sections:

Note

This example uses Cisco APIC release 4.2(x) and the associated GUI screens.

- Example Topology

- Prerequisites

- Create L3Out Using the Create L3Out Wizard

- Review - Create L3Out Using the Create L3Out Wizard

- Configure Advertise the BD Subnet with a Route Map

- Verify the Contract

- Change the OSPF Interface Level Parameters (Optional)

Example Topology

Example Topology for an OSPF L3Out with Two External Routers

This basic L3Out example shows you how to:

- Configure an L3Out with the following specifications

- with Area 0 OSPF

- with two external routers

- with routed interfaces

- on two border leaf switches

- Advertise a BD subnet using default route-map (default-export)

- Allow communication with a contract between EPG1 and external route (10.0.0.0/8)

OSPF Configuration Diagram

The preceding diagram illustrates the configuration for the example topology in Example Topology for an OSPF L3Out with Two External Routers. The configuration flow for this example is as follows:

1. L3Out: This creates

- L3Out itself (OSPF parameters)

- Node, Interface, OSPF I/F Profiles

- L3Out EPG with External Subnets for the External EPG scope

2. Advertise a BD subnet: This uses

- default-export route-map

- BD subnet with Advertise Externally scope

3. Allow EPG - L3Out communication: This uses a contract between EPG1 and L3Out EPG1

Prerequisites

Example Screen of Objects Created as Prerequisites

- This configuration example focuses only on the L3Out configuration part. The other configurations such as for VRF, BD, EPG, Application Profiles, and Access Policies (Layer 3 Domain etc.) are not covered. The preceding screenshot displays the prerequisite tenant configurations that are as follows:

- VRF1

- BD1 with the subnet 192.168.1.254/24

- EPG1 with a static port towards endpoints

See Completed Configurations in XML for REST API for a complete configuration example that includes VRF, BD, EPG, Application Profiles, and Access Policies on top of the L3Out configuration.

Create L3Out Using the Create L3Out Wizard

This task creates the OSPF L3Out described in Example Topology. Following this task, Cisco ACI will be configured with two border leaf switches and OSPF neighborship with two external routers as shown in Example Topology for an OSPF L3Out with Two External Routers.

Procedure

Step 1

In the GUI Navigation pane, under the Tenant Example, navigate to Networking > L3Outs.

Step 2

Right-click and choose Create L3Out.

Step 3

In the Create L3Out screen, Identity tab, perform the following actions:

1. In the Name field, enter the name for an L3Out. (EXAMPLE_L3Out1)

2. In the VRF field and the L3 Domain field, choose the appropriate values. (VRF1, EXAMPLE_L3DOM)

3. In the OSPF field, check the checkbox.

4. In the OSPF Area ID field, choose the value 0 or the text backbone.

5. In the OSPF Area Type field, choose Regular area.

6. Keep the rest of the fields with their default values.

Step 4

Click Next to display the Nodes and Interfaces screen, and perform the following actions:

1. In the Interface Types area, in the Layer 3 field and in the Layer 2 field, ensure that your selections match the choices in the preceding screenshot (Routed and Port).

2. In the Nodes area, in the Node ID field, from the drop-down list, choose the appropriate node ID. (leaf2 (Node 102))

3. In the Router ID field, enter the appropriate router ID. (2.2.2.2)

The Loopback Address field auto populates based on the router ID value you enter. You do not require the loopback address, so delete the value and leave the field blank.

4. In the Interface field, choose the interface ID. (eth1/11)

5. In the IP Address field, enter the associated IP address. (172.16.1.1/30)

6. In the MTU field, keep the default value. (inherit)

7. Click the + icon next to the MTU field to add an additional interface for node leaf2. (Node-102)

8. In the Interface field, choose the interface ID. (eth1/12)

9. In the IP Address field, enter the associated IP address. (172.16.2.1/30)

10. In the MTU field, keep the default value. (inherit)

Step 5

To add another node, click the + icon next to the Loopback Address field, and perform the following actions:

Note

When you click the + icon, the new Nodes area is displayed below the area that you had populated earlier.

1. In the Nodes area, in the Node ID field, from the drop-down list, choose the node ID. (leaf3 (Node-103))

2. In the Router ID field, enter the router ID. (3.3.3.3)

The Loopback Address field auto populates based on the router ID value you enter. You do not require the loopback address, so delete the value and leave the field blank.

3. In the Interface field, choose the interface ID. (eth1/11)

4. In the IP Address field, enter the IP address. (172.16.3.1/30)

5. In the MTU field, keep the default value. (inherit)

6. Click the + icon next to the MTU field to add an additional interface for node leaf3. (Node-103)

7. In the Interface field, choose the interface ID. (eth1/12)

8. In the IP Address field, enter the associated IP address. (172.16.4.1/30)

9. In the MTU field, keep the default value. (inherit), and click Next.

We have specified the node, interface, and IP address for each interface.

Step 6

Click Next to view the Protocols screen.

This screen allows you to specify the OSPF interface level policy to configure hello-interval, network-type, etc.

In this example, nothing is selected. Therefore, the default policy is used. The default OSPF interface profile uses Unspecified as network-type which defaults to broadcast network type. To optimize this with point-to-point network-type for sub-interface, see Change the OSPF Interface Level Parameters (Optional).

Step 7

Click Next.

The External EPG screen is displayed with L3Out EPG details. This configuration is to classify the traffic into the EPG to apply to the contract.

Step 8

In the External EPG screen, perform the following actions:

1. In the External EPG area, Name field, enter a name for the external EPG. (L3Out_EPG1)

2. In the Provided Contract field, do not choose a value.

In this example, there is no provided contract for L3Out_EPG1 because a normal EPG (EPG1) is the provider.

3. In the Consumed Contract field, choose default from the drop-down list.

Step 9

In the Default EPG for all external networks field, uncheck the checkbox, and perform the following actions:

1. Click the + icon in the Subnets area, to display the Create Subnet dialog box.

2. In the IP Address field, enter the subnet. (10.0.0.0/8)

3. In the External EPG Classification field, check the checkbox for External Subnets for the External EPG. Click OK.

Step 10

Click the + icon in the Subnets area once more to display the Create Subnet dialog box, and perform the following actions:

Note

Although this is an optional configuration, it is a best practice to specify the L3Out interface subnets in case endpoints have to communicate with those IPs.

1. In the IP Address field, enter the subnet. (172.16.0.0/21)

This subnet covers all the interfaces in the L3Out. This can be each individual subnet for each routed interface instead.

2. In the External EPG Classification field, check the checkbox for External Subnets for the External EPG. Click OK.

3. Click Finish.

The L3Out OSPF is now deployed.

Review - Create L3Out Using the Create L3Out Wizard

Review how the configuration using the wizard is presented in the Cisco APIC GUI, and verify that the configurations are accurate.

Procedure

Step 1

Navigate to your Tenant_name > Networking > L3Outs > EXAMPLE_L3Out1, in the Work pane, scroll to view the details as follows:

At this location in the GUI, verify the main L3Out parameters such as VRF, domain, and OSPF parameters that are configured in the Identity screen in the Create L3Out wizard.

Step 2

Verify that OSPF is enabled with the specified parameters such as Area ID and Area Type.

Step 3

Under Logical Node Profiles, EXAMPLE_L3Out1_nodeProfile is created to specify border leaf switches with their router IDs.

Step 4

Under Logical Interface Profile, EXAMPLE_L3Out1_interfaceProfile is created.

Verify the interface parameters such as interface ID, IP addresses, in this example, as routed interfaces. The default MAC addresses gets auto populated. OSPF interface profile is also created under this for OSPF interface level parameters.

The review is complete.

Configure Advertise the BD Subnet with a Route Map

In this example, a route map, default-export, is used with the IP prefix list to advertise the BD subnet.

Note

This default-export route map will be applied to the L3Out (EXAMPLE_L3Out1) without being associated to anything specific.

Procedure

Step 1

To enable a BD subnet to be advertised, navigate to Tenant > Networks > Bridge Domains > BD1 > Subnets > 192.168.1.254/24, and select Advertised Externally scope.

Step 2

To create a route map under your L3Out (EXAMPLE_L3Out1), navigate to Route map for import and export route control.

Step 3

Right-click and choose Create Route map for import and export route control.

Step 4

In the Create Route map for import and export route control dialog box, in the Name field, choose default-export.

Step 5

In the Type field, choose Matching Route Policy Only.

Note

Match Routing Policy Only: By choosing this Type with default-export route map, all route advertisement configuration is performed by this route map. BD associations and export route control subnets configured under the external EPG will not apply. You should configure all match rules within this route-map for all routes that will be advertised from this L3Out.

Match Prefix and Routing Policy: By choosing this Type with default-export route map, route advertisement is matched by any match rules configured in this route map in addition to any BD to L3Out associations and export route control subnets defined under the External EPG.

When using a route profile, it is recommended to use Match Routing Policy Only for a simpler configuration that is easier to maintain.

Step 6

In the Contexts area, click the + icon, to display the Create Route Control Context dialog box, and perform the following actions:

1. In the Order field, configure the order. (0)

In this example, we have only one order.

2. In the Name field, enter a name for the context. (BD_Subnets)

3. In the Action field, choose Permit.

This enables the route map to permit the prefix we will configure.

In this example, we require the match rule that requires the IP prefix list, BD1_prefix. This IP prefix list points to the BD subnet advertised.

Step 7

In the Match Rule field, create the IP prefix-list by performing the following actions;

1. Choose Create Match Rule for a Route-Map.

2. In the Name field, enter a name BD1_prefix.

3. In the Match Prefix area, click the + icon, and enter the BD subnet (192.168.1.0/24).

Verify the Contract

In this task, you verify the contract to enable communication between an endpoint (192.168.1.1) and external prefixes (10.0.0.0/8, and optionally 172.16.0.0/21). In this example, the EPG for the endpoint is EPG1 and the external EPG for external prefixes is L3Out_EPG1.

The required configuration should already be present from the Create L3Out wizard.

Procedure

Step 1

Under your L3Out, navigate to External EPGs > L3Out_EPG1.

Step 2

In the Work pane, in the External EPG Instance Profile area, under Policy > General sub-tab, look at the Properties and verify that the two subnets are displayed with External Subnets for the External EPG.

Step 3

Next, click the Contracts sub-tab and verify the contract you specified earlier is consumed correctly. In case you want to add more contracts, you can perform the actions from this location in GUI.

Step 4

Navigate to Application Profile > Application EPGs > EPG1 > Contracts, and verify that EPG1 is providing the appropriate contract.

Change the OSPF Interface Level Parameters (Optional)

If you wish to change the OSPF interface-level parameters, such as Hello Interval, OSPF network type, then you can configure it in the OSPF Interface Profile. The node level OSPF parameters are already configured.

Procedure

Step 1

Under your L3Out, navigate to Logical Interface Profile > EXAMPLE_L3Out1_interfaceProfile > OSPF Interface Profile.

Step 2

In the Work pane, in the Properties area, choose the OSPF Interface Policy you wish to use.

This modifies your OSPF interface level parameters.

Completed Configurations in XML for REST API

This appendix contains the following sections:

- Uploading Example Files in Cisco APIC GUI

- Completed Configuration Examples

Uploading Example Files in Cisco APIC GUI

The following steps show how to upload the XML example files.

Note

Although the following steps use Tenant as an example to trigger POST, the examples in this document can be uploaded from any other location in the Cisco APIC GUI such as VRF, Access Policies etc. Whichever location you use, you must modify the parent DN to uni/.

Procedure

Step 1

Log in to your Cisco APIC GUI, and navigate to Tenants.

Step 2

In the Tenants tab, click an existing tenant name such as infra or common.

Step 3

In the left Navigation pane, below Quick Start, right-click the Tenant name, and click Post.

Step 4

In the parent DN field, change the value to uni/ by removing all additional content.

Step 5

In the File Name field, browse to the .xml file on your desktop that you wish to upload, choose it, and click Post.

The contents of the XML file is uploaded in Cisco APIC, and the configured objects are displayed in Cisco APIC GUI.

Step 6

To upload additional example files, repeat the above set of steps.

Completed Configuration Examples

Download the following XML example files and upload them in your Cisco APIC GUI. This enables you to obtain the completed configurations for each example along with some of the prerequisites.

- MP-BGP Setup

- Example 1 - An OSPF L3Out With Two External Routers

MP-BGP Setup

Infra MP-BGP

Contents: BGP Route reflector policy along with Pod Policy Group and Pod Profile

URL: https://www.cisco.com/c/dam/en/us/td/docs/switches/datacenter/aci/apic/example-files/L3Out_Example_infra_MP-BGP.xml

Example 1 - An OSPF L3Out With Two External Routers

Access Policy

Contents: L3 Domain, interface profiles, etc.

URL: https://www.cisco.com/c/dam/en/us/td/docs/switches/datacenter/aci/apic/example-files/L3Out_Example1_AccessPolicies.xml

Tenant

Contents: L3Out, VRF, BD, EPG, etc.

URL: https://www.cisco.com/c/dam/en/us/td/docs/switches/datacenter/aci/apic/example-files/L3Out_Example1_TenantPolicies.xml

Preface

This preface includes the following sections:

- Audience

- Related Content

- Documentation Feedback

- Obtaining Documentation and Submitting a Service Request

Audience

This guide is intended primarily for data center administrators with responsibilities and expertise in switch and network administration with responsibilities and expertise in one or more of the following areas:

- Cisco ACI connectivity to external networks using routing protocols

- Cisco ACI connectivity to external networks using static protocols

Related Content

For additional details about Cisco ACI L3Out, the following documents are available at these URLs:

- Cisco APIC Layer 3 Networking Configuration Guide

- Cisco ACI Fabric L3Out Guide

All Cisco ACI documentation is available at the following link: Cisco Application Centric Infrastructure (ACI) Documentation

Documentation Feedback

To provide technical feedback on this document, or to report an error or omission, please send your comments to apic-docfeedback@cisco.com. We appreciate your feedback.

Obtaining Documentation and Submitting a Service Request

For information on obtaining documentation, using the Cisco Bug Search Tool (BST), submitting a service request, and gathering additional information, see What's New in Cisco Product Documentation, at: https://www.cisco.com/warp/public/687/Directory/DirTAC.shtml.

Subscribe to What's New in Cisco Product Documentation, which lists all new and revised Cisco technical documentation as an RSS feed and delivers content directly to your desktop using a reader application. The RSS feeds are a free service.

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