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

In an application-centric design, the creation of additional EPGs under one bridge domain is possible. This allows for greater flexibility in managing and segmenting network traffic for different applications or services within the same bridge domain.

References := Network Centric to ACI Centric Migration - Cisco

 When EPGs (Endpoint Groups) are stretched across sites, Layer 2 flooding is available across these sites. This allows for the extension of the Layer 2 domain and the sharing of broadcast, unknown unicast, and multicast traffic between EPGs at different locations.

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

Removing pre-existing Fibre Channel over Ethernet (FCoE) configurations from Nexus devices is necessary to ensure compatibility with Cisco ACI mode. FCoE configurations are not supported in ACI mode, and their presence can hinder the migration process2.

 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

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

When Server A is connected to the Cisco ACI fabric using teamed interfaces with one active and one standby interface, enabling ARP flooding ensures that the ACI fabric can learn about the new active interface after a failover. This allows for seamless communication continuity even when the standby interface becomes active and starts sending traffic with its built-in MAC address.

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In a Cisco ACI Multi-Site deployment, proper configuration of the inter-site link is crucial for traffic to pass between different sites. The MTU size is particularly important; if it’s not set correctly, packets may be dropped or fragmented, leading to connectivity issues. By configuring the MTU on the link to be at least 100 bytes larger than that of the ACI fabrics, you allow for encapsulation overhead without packet drops due to exceeding MTU limits. Additionally, configuring the link as a routed subinterface using VLAN-4 is necessary for routing across different broadcast domains, which is essential for inter-site communication in an ACI fabric. References: Implementing Cisco Application Centric Infrastructure Official Cert Guide

For intra-VRF transit routing between two external routers in different OSPF areas, OSPF virtual links are required. They connect non-contiguous areas to the backbone area, ensuring all areas can communicate even if not directly connected.

References := Implementing Cisco Application Centric Infrastructure Official Cert Guide

 When Leaf 1002 receives a packet from a host attached to Leaf 1001, it learns the MAC address of the source from Leaf 1001. Additionally, Leaf 1002 learns the IP address of the source.

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

 The correct configuration to prefer the local Policy-Based Routing (PBR) node and redirect traffic to the remote pod PBR node in case of catastrophic failure is option D: location-based PBR, host route advertisement, and node tracking. Location-based PBR allows for the selection of a preferred path based on the location of the traffic source or destination. Host route advertisement enables specific routing information to be propagated throughout the network, which can be used to influence traffic flow. Node tracking provides a mechanism to monitor node status and reroute traffic if a node becomes unavailable due to failure. References := ( Implementing Cisco Application Centric Infrastructure Official Cert Guide )

In the given scenario where CDP is disabled, LLDP is enabled, and LACP is in Active mode between Cisco UCS FIs and Cisco ACI leaf switches for the DVS setup, the compatible discovery protocol would be LLDP since it’s already enabled. As for load-balancing mechanisms with this setup: MAC Pinning can be used without relying on any link discovery protocol like CDP or LACP; hence option B is valid. Option F suggests usingLACP in Passivemode, whichcould complement the existing Active mode on other devicesto establishan LACP negotiation successfully. References: =Implementing Cisco Application Centric Infrastructure Official Cert Guide

 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

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 limit both local and remote endpoint learning to instances where the source IP address belongs to a bridge-domain subnet in the VRF instance, the action that should be taken inside the Cisco APIC is to enable the “Enforce Subnet Check” feature. This configuration ensures that IP addresses outside the configured subnets for the bridge domain are not learned, preventing mis-learning of IP addresses that do not belong to the fabric12.

 For a Cisco ACI leaf switch to correctly learn the remote endpoint MAC, the VXLAN packet received from the Cisco ACI spine must include bridge domain information. The bridge domain contains the Layer 2 forwarding context, which allows the leaf switch to learn and associate the MAC address with the correct bridge domain3.

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 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

When allowing routes learned from one L3Out to be advertised out another L3Out, the Export Route Control Subnet should be enabled, and Aggregate Export should also be enabled. This configuration allows the necessary routes within the specified CIDR block to be aggregated and advertised out, facilitating efficient route advertisement without the need for an explicit list of all routes.

References: Implementing Cisco Application Centric Infrastructure Official Cert Guide

The topology change notification (TCN) in Spanning Tree Protocol (STP) triggers a flush of the MAC address table. When a leaf node receives a TCN, it flushes the MAC address entries associated with the VLANs affected by the topology change. In this case, since the TCN is related to VLAN 101, the ACI fabric will flush all endpoints associated with VLAN 101 in bridge domain BD10123 on the leaf node.

The VXLAN source port adds entropy to the overlay packet forwarding by using a hash of the inner packet’s Layer 2, Layer 3, and Layer 4 headers. This entropy enables Equal-Cost Multi-Path (ECMP) routing, allowing for multiple parallel paths in the network, which increases bandwidth and redundancy2.

References := VXLAN Traffic Forwarding | VXLAN Packet Flow

 To prevent connectivity issues for EP1 when accessing an external L3Out network, it’s essential to enable IP data plane learning for the VRF and unicast routing in BD-BD2. IPdata plane learning allows dynamic endpoint learning within a VRF, ensuring accurate forwarding information for EP1. Unicast routing enables packet routing based on destination IP, facilitating proper traffic routing through the gateway.

References := Implementing Cisco Application Centric Infrastructure Official Cert Guide

In a Cisco ACI Multi-Site fabric, when the Inter-Site BUM Traffic Allow option is enabled in a specific stretched bridge domain, ingress replication on the spines in the source site is used to forward Broadcast, Unknown unicast, and Multicast (BUM) traffic to all endpoints in the same broadcast domain. This method ensures that BUM traffic is efficiently replicated across the fabric, reaching all relevant endpoints without overwhelming the network with unnecessary traffic4.

References := Solved: Cisco ACI Multipod - BUM traffic - Cisco Community.

 In a stretched bridge domain solution between Cisco ACI sites with Layer 2 flood disabled, headend replication is used for broadcast, unknown unicast, and multicast (BUM) traffic between sites. This approach optimizes traffic flow and reduces unnecessary flooding across the network1.

References := Implementing Cisco Application Centric Infrastructure Official Cert Guide

 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.

 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

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 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.