Implementing an active-active firewall cluster stretched across separate pods with anycast services configured offers several advantages, one of which is that it allows for optimized routing within the Cisco ACI fabric. When anycast services are used, each pod can have its own anycast node (firewall instance), and due to routing preferences set within ACI’s spine switches, they will prefer their local pod’s anycast node for routing decisions. This preference enhances efficiency by reducing cross-pod traffic and improving response times since local spines direct traffic to their respective local pod’s anycast nodes.  References : Implementing Cisco Application Centric Infrastructure Official Cert Guide

For fabric discovery to be successful for the nodes in Pod 2, the engineer should configure POD 2 Data Plane TEP under the Pod Connection Profile. This action establishes the necessary data plane tunnel endpoint for communication between the pods.  References  :=  Troubleshoot ACI Fabric Discovery - Multi-Pod Discovery - Cisco ,  Which action should be taken for fabric discovery to be successful for…

The outer destination IP address in the VXLAN encapsulated packet for Layer 2 Broadcast, Unknown-unicast, and Multicast (BUM) traffic sent between two Cisco ACI sites is the Overlay Multicast TEP (Tunnel Endpoint). This address ensures efficient replication of BUM traffic across different sites in the ACI fabric.

References  :=  Cisco APIC Layer 2 Networking Configuration Guide

Within Cisco ACI, when a Topology Change Notification (TCN) BPDU is received in a VLAN, the system flushes the endpoints for the associated encapsulation to ensure network stability.  Additionally, BPDU filter and BPDU guard can be configured on Cisco ACI leaf edge ports to protect against potential STP issues 2 .

 For a full mesh Cisco ACI Multi-Site architecture, configuring the BGP-EVPN Router-ID on each spine is essential.  This configuration ensures unique identification and proper routing of traffic within the overlay network 1

The control plane TEP (Tunnel Endpoint) IP address is a unique IP address assigned to each spine node within a Cisco ACI fabric. This IP address is used to establish MP-BGP EVPN (Multiprotocol Border Gateway Protocol Ethernet VPN) and VPNv4 (VPN version 4) adjacencies with the spine nodes in remote sites when configuring Cisco ACI Multi-Site. The control plane TEP IP enables the spine nodes to exchange routing information and network reachability for seamless integration of multiple sites into a single ACI fabric.  References  := Implementing Cisco Application Centric Infrastructure Official Cert Guide

In an ACI setup, to advertise a default static route from L3Out-1 to another L3Out using OSPF, the Aggregate Export Subnet feature must be enabled. This allows for the summarization and advertisement of routes, including the default route, to external networks via OSPF.

References  := Implementing Cisco Application Centric Infrastructure Official Cert Guide

The Forwarding Tag (FTAG) in Cisco ACI is used to load balance multi-destination traffic. FTAG trees facilitate efficient forwarding of multicast traffic within the fabric, ensuring optimal distribution and load balancing across multiple paths.  All multi-destination traffic is encapsulated within VXLAN, and FTAG trees play a crucial role in achieving efficient traffic flow 3 4 5 .

References : Implementing Cisco Application Centric Infrastructure Official Cert Guide

In a Cisco ACI Multi-Pod design, having separate Layer 3 Out (L3Out) connections for each pod is recommended when implementing active-standby firewalls in different pods. This setup allows for independent routing and failover mechanisms, ensuring that each pod can maintain external connectivity even if one firewall fails.

References  := Implementing Cisco Application Centric Infrastructure Official Cert Guide

The design approach shown in the exhibit is application-centric. This model focuses on the application requirements and defines network policies based on the needs of the application rather than traditional network constructs. It allows for a more dynamic and flexible network configuration that aligns with the application’s behavior and interactions.