Common Pervasive Gateway

This chapter contains the following sections:

Common Pervasive Gateway Overview

The Common Pervasive Gateway is a legacy feature that allows two Cisco ACI fabrics to be configured with an IPv4 common gateway on a per bridge domain basis.

  • Enables VM or host mobility across fabrics while retaining IP addresses.

  • Supports automatic VM host moves via hypervisors.

  • Functions across co-located or multi-site deployments using local or bridged Layer 2 connections.

Deployment Considerations and Topology


Warning

The Common Pervasive Gateway feature is deprecated and not actively maintained. Cisco highly recommends deploying Multi-Site instead of interconnecting multiple individual ACI fabrics through leaf switches. This feature is not supported for new topologies due to lack of validation for features such as L3 multicast.


Important

Depending upon the topology used to interconnect two Cisco ACI fabrics, it is required that the interconnecting devices filter out the traffic source with the Virtual MAC address of the gateway switch virtual interface (SVI).

The following figure illustrates the basic common pervasive gateway topology.

Figure 1. Common Pervasive Gateway Topology

Configuration Example

This example shows how to configure Common Pervasive Gateway for IPv4 when using the Cisco APIC .

Configuring Common Pervasive Gateway Using the GUI

Before you begin

  • The tenant and VRF are created.

  • The bridge domain virtual MAC address and the subnet virtual IP address must be the same across all Cisco Application Centric Infrastructure ( ACI ) fabrics for that bridge domain. Multiple bridge domains can be configured to communicate across connected Cisco ACI fabrics. The virtual MAC address and the virtual IP address can be shared across bridge domains.

  • The Bridge domain that is configured to communicate across Cisco ACI fabrics must be in flood mode.

  • Only one EPG from a bridge domain, if the bridge domain has multiple EPGs, should be configured on a border leaf switch on the port which is connected to the second fabric.

  • Do not connect hosts directly to an inter-connected Layer 2 network that enables a pervasive common gateway among the two Cisco ACI fabrics.

Procedure

Step 1

On the menu bar, click Tenants .

Step 2

In the Navigation pane, expand the Tenant_name > Networking > Bridge Domains .

Step 3

Right-click Bridge Domains , and click Create Bridge Domain .

Step 4

In the Create Bridge Domain dialog box, perform the required actions to choose the appropriate attributes:

  1. In the Main tab, in the Name field, enter a name for the bridge domain, and choose the desired values for the remaining fields.

  2. In the L3 configurations tab, expand Subnets , and in the Create Subnets dialog box, in the Gateway IP field, enter the IP address.

    For example, 192.0.2.1/24.

  3. In the Treat as virtual IP address field, check the check box.

  4. In the Make this IP address primary field, check the check box to specify this IP address for DHCP relay.

    Checking this check box affects DHCP relay only.

  5. Click Ok , then click Next to advance to the Advanced/Troubleshooting tab, then click Finish .

Step 5

Double click the Bridge Domain that you just created in the Work pane, and perform the following action:

  1. Click the Policy tab, then click the L3 Configurations subtab.

  2. Expand Subnets again, and in the Create Subnets dialog box, to create the physical IP address in the Gateway IP field, use the same subnet which is configured as the virtual IP address.

    For example, if you used 192.0.2.1/24 for the virtual IP address, you might use 192.0.2.2/24 here for the physical IP address.

    Note

     

    The physical IP address must be unique across the Cisco ACI fabric.

  3. Click Submit to complete the configuration in the Create Subnet window.

Step 6

In the L3 Configurations tab for the same bridge domain that you just created, click the Virtual MAC Address field, and change Not Configured to the appropriate value, then click Submit .

Note

 

The default bridge domain MAC address values are the same for all Cisco ACI fabrics; this configuration requires the bridge domain MAC values to be unique for each Cisco ACI fabric.

Confirm that the bridge domain MAC (pMAC) values for each fabric are unique.

Note

 

This step essentially ties the virtual MAC address that you enter in this field with the virtual IP address that you entered in the previous step. If you were to delete the virtual MAC address at some point in the future, you should also remove the check from the Treat as virtual IP address field for the IP address that you entered in the previous step.

Step 7

To create an L2Out EPG to extend the bridge domain to another fabric, in the Navigation pane, right-click L2Outs , click Create L2Out , and perform the following actions:

  1. In the Name field, enter a name for the bridged outside.

  2. In the Bridge Domain field, select the bridge domain already previously created.

  3. In the Encap field, enter the VLAN encapsulation to match the other fabric l2out encapsulation.

  4. In the Path Type field, select Port , PC , or VPC to deploy the EPG and click Next .

  5. To create an External EPG network click in the Name field, enter a name for the network and you can specify the QoS class and click Finish to complete Common Pervasive configuration.