300-630 Implementing Cisco Application Centric Infrastructure - Advanced (DCACIA) Questions and Answers

 In Cisco ACI, contracts define the policies for communication between EPGs (Endpoint Groups). For a client in WebClient EPG to establish an HTTP connection toward a server in WebServer EPG, the contract must allow the initiation of communication from WebClientto WebServer. Since HTTP uses port 80, the destination port (DST Port) should be set to 80 as per standard HTTP communications. The option “Apply Both Direction DISABLED” means that only the initiator of the connection (in this case, WebClient EPG) can send traffic unless specified otherwise by another contract or filter. The “Reverse Port Filter ENABLED” allows return traffic from WebServer EPG back to WebClient EPG on dynamically allocated source ports used by WebClient when initiating the connection. This combination ensures that clients can initiate an HTTP request and receive responses from servers. References: = Implementing Cisco Application Centric Infrastructure Official Cert Guide

In the Cisco ACI fabric, to ensure that the IP address of Server S1 is learned and the IP addresses of BC1 and BC2 are not learned, one must limit IP learning to a specific subnet and suppress ARP responses from BC1 and BC2. By checking the “Limit IP learning to subnet” box (Option A), it ensures that only IPs within a defined subnet are learned, which would include Server S1’s IP but exclude BC1 and BC2 if they are outside of this subnet.Suppressing ARP response on BC1 and BC2 (Option D) prevents these devices from responding to ARP requests, which in turn prevents their IPs from being learned by other devices in the network. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

 The output shows details of tunnel 6 within a Cisco ACI fabric. The transport protocol is listed as “isvlan,” which is typically associated with the GRE protocol in Cisco ACIterminology. GRE, a tunneling protocol developed by Cisco, encapsulates various network layer protocols inside virtual point-to-point links over an IP internetwork. References: Implementing Cisco Application Centric Infrastructure Official Cert Guide

To implement the vPC (Virtual Port Channel) in the Cisco ACI fabric, one should select a common vPC interface policy group (Option A), select common interface profiles (Option C), and select common switch profiles (Option E). These steps ensure that both switches in a vPC domain are configured with consistent policies and profiles for interfaces and switches. This consistency is crucial for the proper functioning of a vPC setup where two or more links that are physically connected to two different Cisco ACI leaf switches appear as a single “logical” port channel to a third device, like the depicted WebServer.

 To set up the link between the spine and the IPN device in a Cisco ACI Multi-Pod, the following actions should be taken: A. Enable MP-BGP routing to facilitate the exchange of routing information. B. Enable BIDIR-PIM protocol to support efficient multicast traffic forwarding. D. Enable OSPF routing to ensure dynamic routing between the spine and IPN devices.

 To allow communication between two application profiles that are configured in the same tenant but different VRFs, the contract scope must be set to ‘tenant.’ This is because the contract scope defines the level at which the contract is enforced. A ‘tenant’ scope means the contract applies to all application profiles within the same tenant, regardless of the VRFs they are in. This allows for the necessary route-leaking between the provider and consumer VRFs to enable communication between the application profiles.

 For new nodes in a Cisco ACI Multi-Pod environment to be discoverable by existing APICs, DHCP relay needs to be enabled on the IPN devices’ links connected to the ACI spines. This allows the new nodes to obtain an IP address and be recognized by the APICs for integration into the fabric.

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…

 In a Cisco ACI Multi-Site setup, the source leaf is responsible for flooding BUM (Broadcast, Unicast, and Multicast) traffic to the specific multicast group or GIPo (Group IP Overlay). This process involves the ingress replication function on the spine nodes of the source site to replicate BUM traffic to all remote sites where the bridge domain is stretched12.

References := Cisco ACI Multi-Site Architecture White Paper, ACI Multi-Site Data Plane Communication - DCLessons

Bidirectional Protocol Independent Multicast (Bidirectional PIM) is used between the inter-pod network (IPN) and spines within each pod in a Cisco ACI environment to allow broadcast traffic replication between pods. This protocol is designed to efficiently route multicast traffic in scenarios where the same data is being sent to multiple receivers, which aligns with the need for broadcast traffic replication in an interconnected multi-pod ACI architecture. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

In a Cisco ACI Multi-Pod deployment, the spine switches within a pod should not be directly connected to the spine switches in another pod. Instead, they should be connected to an IPN (Inter-Pod Network) device that provides Layer 3 IP connectivity between the pods. This setup allows for the extension of the ACI fabric across multiple locations while maintaining a single logical fabric. The IPN device can be a router or a switch with Layer 3 capabilities that can handle the necessary routing protocols and encapsulation methods required for Multi-Pod communication. References := Implementing Cisco Application Centric Infrastructure Official Cert Guide

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

To prevent MAC flapping on Cisco UCS Fabric Interconnects and ACI leaf switches, MAC Pinning should be selected for the VMM vSwitch Port Channel policy. This ensures consistent uplink usage for each virtual machine’s traffic, avoiding MAC address movement across multiple uplinks.

References := Implementing Cisco Application Centric Infrastructure Official Cert Guide

 In Cisco ACI, the spines suppress STP BPDUs to prevent them from being forwarded to other pods. This behavior ensures that the ACI fabric operates efficiently without relying on STP for loop prevention.

References := Cisco APIC Layer 2 Networking Configuration Guide, Release 5.2(x)

 Anycast services in a Cisco ACI fabric allow services like firewalls to be stretched across multiple pods, providing high availability and resiliency. The correct setups for implementing anycast services include configuring the firewalls behind an EPG subnet ©and deploying a Layer 4 to Layer 7 service graph with Policy-Based Routing (PBR) (E). Modifying the ACI contract scope (A) or the MAC address on the second firewall (B) are not related to anycast service implementation. Deselecting No Default SVI Gateway under EPG Subnet (D) is not a setup for anycast services1. References := (Cisco APIC Online Help - About Anycast Services2)

The minimum MTU value that must be supported by the ISN to allow control plane endpoint information exchange between sites in a Cisco ACI Multi-Site setup with default settings is 1554 bytes (B). This accounts for the standard MTU of 1500 bytes plus additional overhead for VXLAN encapsulation. An MTU of 9000 (A) or 9100 © is not the minimum required, and 1600 (D) is not related to the default fabric settings5. References := (Multi-site / Multi-Pod MTU Jumbo Frames5)

 In a Cisco ACI Multi-Site setup, the ISN (Inter-Site Network) connects different ACI sites. For efficient multicast traffic routing, BIDIR-PIM (Bidirectional Protocol Independent Multicast) is configured throughout the ISN, which is why option B is correct. Increasing the ISN MTU (Maximum Transmission Unit) to support the maximum MTU sent by endpoints is crucial to prevent packet fragmentation or loss, making option C correct.

Options A, D, and E are not typically required for an ACI Multi-Site setup. Direct connectivity between Spine switches and ISN routers, as mentioned in options A and D, is usually established through leaf switches. Option E, enabling IGMPv3 on ISN routers, is more relevant for managing multicast subscriptions within a single site.

References: = Implementing Cisco Application Centric Infrastructure Official Cert Guide

The Endpoint Group (EPG) scope is the correct choice to meet the requirements for the e-commerce software in a Cisco ACI fabric. By selecting the EPG scope, contracts can be reused within the same Virtual Routing and Forwarding (VRF) context, reducing the overall number of contracts. Additionally, it ensures that the e-commerce software communicates only with software EPGs that are part of the same Application Network Profile (ANP), while preventing communication with applications in different ANPs. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

To create an exit point from all the tenants using the common tenant after removing RT-2 and RT-3 devices, the following two configuration tasks must be completed:

Update L3Out ExtEPG Subnet: The L3Out ExtEPG subnet in the common tenant should be updated with the flag “Shared Route Control Subnet” and “Aggregate Shared Routes” (Option C). This configuration allows for the sharing of routes between different tenants through a common exit point.

Mark Subnets and Attach Contract: All subnets should be marked with the flag “Shared between VRFs,” and contract Ctr-3 should be attached as a provider to all the EPGs (Option D). This ensures that all EPGs can provide services under contract Ctr-3 across different VRFs, facilitating inter-tenant communication via shared routes. References := (Implementing Cisco Application Centric Infrastructure Official Cert Guide)

Protocol Independent Multicast sparse mode (PIM-SM) is designed for efficient routing to multiple receivers in a multicast group across an inter-pod network (IPN). PIM sparse mode is best suited for environments where receivers are dispersed because it allows for explicit join messages to control the flow of traffic. This makes it ideal for scenarios where broadcast, unknown unicast, and multicast flooding between Cisco ACI pods is required. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

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

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.

In a network-centric design within Cisco ACI, there is open communication between EPGs, and a bridge domain typically has one subnet and one EPG. This design is often used for initial migrations and is based on traditional networking concepts.

References := Network Centric to ACI Centric Migration - Cisco

 In Cisco ACI, shared services like firewalls should be configured in the common tenant. This allows all tenants to access the services without duplicating them in each tenant.

In a Cisco ACI environment, STP BPDUs are not forwarded across the fabric. The ACI fabric is designed to operate without STP, using a policy-driven, multi-path Ethernet model for loop prevention. Thus, STP BPDUs from external switches are dropped by the ACI leaf switches. References := (Implementing Cisco Application Centric Infrastructure Official Cert Guide)

 In a Cisco ACI environment, when an ARP request is initiated by VM1 for VM2 and VM2 is not known within the ACI fabric, the leaf switch (Leaf 101) will forward the ARP request to a spine switch that acts as a proxy VTEP. The spine switch will either respond to the ARP request if it knows VM2’s location through the COOP database or will flood the ARP request within the fabric if VM2’s location is unknown. References: Implementing Cisco Application Centric Infrastructure Official Cert Guide

 For the Cisco ACI leaf to learn individual MAC addresses from the same physical port, “MAC pinning” mode must be enabled in the vSwitch policy configuration. This mode allows each ESXi vSwitch port group to pin to a specific uplink or set of uplinks, enabling independent MAC address learning for each pinned uplink, which is essential for distinguishing multiple VMs on an ESXi host by the leaf switch. References: Implementing Cisco Application Centric Infrastructure Official Cert Guide

 In a Cisco ACI fabric, multicast traffic is managed using FTag trees that are rooted at the spine nodes. The Cisco APIC automatically determines the roots of these trees. This method optimizes the distribution of multicast traffic across the fabric by leveraging the spine nodes as centralized points for multicast routing and replication456.

References := Implementing Cisco Application Centric Infrastructure Official Cert Guide

 In Cisco ACI, contracts are used to define the policies that govern communication between End Point Groups (EPGs). A contract specifies which types of traffic are permitted or denied between EPGs. To allow all IP traffic except SSH, you would configure the contract to permit all IP traffic and then deny SSH specifically. This is typically done by defining filters within the contract that match on the SSH protocol and setting the action to deny.

References:

Implementing Cisco Application Centric Infrastructure - Advanced (DCACIA) course materials and official certification guide can provide more detailed information on this topic12.

Cisco’s official documentation and training materials are also a good resource for understanding the configuration and management of contracts in ACI

 In a stretched bridge domain solution between Cisco ACI sites with Layer 2 flood enabled, spine head-end replication is utilized to forward Broadcast, Unknown unicast, and Multicast (BUM) traffic between the sites. This method leverages the spine switches at each site to replicate BUM traffic to other sites, ensuring that all endpoints within the stretched bridge domain can receive such traffic. This approach is chosen over ISN multicast replication because it simplifies the overall design and reduces bandwidth consumption on inter-site links by avoiding unnecessary duplication of BUM traffic. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

When traffic to certain endpoints is dropped in a Cisco ACI fabric configured with hardware proxy, setting the L2 Unknown Unicast option to Flood for Layer 2 switched traffic can prevent this problem. This mode allows unknown unicast traffic to be flooded within the bridge domain, rather than being sent to the spine proxy and potentially discarded if the destination is unknown5.

References := Solved: Unknown Unicast in ACI Fabric - Cisco Community

 In a Cisco ACI Multi-Pod environment that is expanding, spine headend replication should be configured to ensure efficient forwarding of BUM (Broadcast, Unknown unicast, Multicast) traffic across the IPN (Inter-Pod Network). This configuration optimizes the control plane scaling and ensures that BUM traffic is handled effectively, maintaining network performance and stability.

References: Implementing Cisco Application Centric Infrastructure Official Cert Guide