External layer 3 outside connection types

The external Layer 3 Outside connections are supported on these interfaces:

• Layer 3 Routed Interface

• Subinterface with 802.1Q tagging - With subinterface, you can use the same physical interface to provide a Layer 2 outside connection for multiple private networks.

• Switched Virtual Interface (SVI) - With an SVI interface, the same physical interface that supports Layer 2 and Layer 3 and the same physical interface can be used for a Layer 2 outside connection and a Layer 3 outside connection.

The managed objects that are used for the L3Outside connections are:

• External Layer 3 Outside (L3ext): Routing protocol options (OSPF area type, area, EIGRP autonomous system, BGP), private network, External Physical domain.

• Logical Node Profile: Profile where one or more nodes are defined for the external Layer 3 Outside connections. The configurations of the router-IDs and the loopback interface are defined in the profile.

  Note

  Use the same router-ID for the same node across multiple external Layer 3 Outside connections.

  Note

  Within a single L3Out, a node can only be part of one Logical Node Profile. Configuring the node to be a part of multiple Logical Node Profiles in a single L3Out might result in unpredictable behavior, such as having a loopback address pushed from one Logical Node Profile but not from the other. Use more path bindings under the existing Logical Interface Profiles or create a new Logical Interface Profile under the existing Logical Node Profile instead.

• Logical Interface Profile: IP interface configuration for IPv4 and IPv6 interfaces. It is supported on the Route Interfaces, Routed subinterfaces, and SVIs. The SVIs can be configured on physical ports, port-channels, or vPCs.

• OSPF Interface Policy: Includes details such as OSPF Network Type and priority.

• EIGRP Interface Policy: Includes details such as Timers and split horizon.

• BGP Peer Connectivity Profile: The profile where most BGP peer settings, remote-as, local-as, and BGP peer connection options are configured. You can associate the BGP peer connectivity profile with the logical interface profile or the loopback interface under the node profile. This determines the update-source configuration for the BGP peering session.

• External Layer 3 Outside EPG (l3extInstP): The external EPG is also referred to as the prefix-based EPG or InstP. The import and export route control policies, security import policies, and contract associations are defined in this profile. You can configure multiple external EPGs under a single L3Out. You may use multiple external EPGs when a different route or a security policy is defined on a single external Layer 3 Outside connections. An external EPG or multiple external EPGs combine into a route-map. The import/export subnets defined under the external EPG associate to the IP prefix-list match clauses in the route-map. The external EPG is also where the import security subnets and contracts are associated. This is used to permit or drop traffic for this L3out.

• Action Rules Profile: The action rules profile is used to define the route-map set clauses for the L3Out. The supported set clauses are the BGP communities (standard and extended), Tags, Preference, Metric, and Metric type.

• Route Control Profile: The route-control profile is used to reference the action rules profiles. This can be an ordered list of action rules profiles. The Route Control Profile can be referenced by a tenant BD, BD subnet, external EPG, or external EPG subnet.

There are more protocol settings for BGP, OSPF, and EIGRP L3Outs. These settings are configured per tenant in the ACI Protocol Policies section in the GUI.

Note

When configuring policy enforcement between external EPGs (transit routing case), you must configure the second external EPG (InstP) with the default prefix 0/0 for export route control, aggregate export, and external security. In addition, you must exclude the preferred group, and you must use an any contract (or desired contract) between the transit InstPs.