Pass the Cisco CCNP Data Center 300-620 Questions and answers with CertsForce

 For Cisco ACI IPN (Inter-Pod Network) to manage multidestination traffic, multicast routing is a requirement. This is because multidestination traffic includes broadcast, unknown unicast, and multicast (BUM) traffic, which needs to be efficiently transported across different pods in a Cisco ACI Multi-Pod environment. Multicast routing protocols like Bidirectional Protocol-Independent Multicast (Bidir PIM) are used to handle this type of traffic1.

References :=

Cisco Application Centric Infrastructure Multi-Pod Configuration White Paper1

Storm control should be configured on port channel on a single leaf switch (Option B) and endpoint-facing trunk interface (Option D) to protect against broadcast traffic6. These interfaces are where storm control policies are typically applied to prevent disruptions caused by traffic storms6.

https://learnduty.com/cisco-aci/aci-multi-pod-overview-and-basics/

 When migrating the vSphere Management VMkernel of all ESXi hosts from the standard default virtual switch to a Virtual Distributed Switch (VDS) that is integrated with APIC in a VMM domain, it is essential to set the Management VMkernel EPG resolution to Pre-Provision. This action ensures that the necessary policies are in place on the ACI fabric before the migration occurs, allowing for a seamless transition and continuous management connectivity.

To detect and prevent Layer 2 loops in a Cisco ACI fabric, the engineer must configure the Mis-Cabling Protocol (MCP) and related policies. MCP is designed to detect loops in Layer 2 network segments connected to ACI access ports and operates in conjunction with Spanning Tree Protocol (STP) running on external Layer 2 networks. The steps to accomplish these goals include:

Enable MCP Globally: Ensure that MCP is enabled globally on all access ports, virtual ports, and virtual port channels (VPCs) unless they are disabled at the individual port level1.

Configure MCP Transmit Frequency: Set the transmit frequency to a value that allows for quick loop detection. Starting with the 3.2(1) release, the Cisco ACI fabric provides faster loop detection with transmit frequencies from 100 milliseconds to 300 seconds1.

Set Action on Loop Detection: Decide how the MCP policies will act upon loop detection. Options include generating a syslog message or disabling the port upon detection of a loop1.

Implement Error Disabled Recovery Policy: Configure an error disabled recovery policy to automatically re-enable ports that were disabled due to loop detection after a configurable interval1.

By following these steps, the engineer can ensure that the Cisco ACI fabric will detect and prevent Layer 2 loops, thereby maintaining a stable and efficient network environment.

References :=

Cisco APIC Online Help - Loop Detection1

ACI Layer 2 loop detection and Mitigation - Cisco Video Portal2

To configure leaf and spine switches in a Cisco ACI fabric to use out-of-band management for NTP protocol, an Override Policy with NTP Out-of-Band must be created. This policy specifies that NTP traffic should be directed through the out-of-band management network, separate from the in-band management traffic, ensuring dedicated management connectivity for time synchronization.

https://www.cisco.com/c/en/us/support/docs/cloud-systems-management/application-policy-infrastructure-controller-apic/200128-Configuring-NTP-in-ACI-Fabric-Solution.html

In a two-pod Cisco ACI Multi-Pod environment, it is recommended to deploy no more than two Cisco APIC controllers in the same pod to avoid losing all replicas of a shard if a pod fails. The APIC cluster is a distributed system where each APIC contains a replica of the configuration database, referred to as a shard. If all replicas of a shard were located in the same pod and that pod were to fail, it would result in the loss of the shard and potentially impact the entire fabric’s operation. By distributing the APIC controllers across pods, the risk of losing all replicas due to a single point of failure is mitigated, enhancing the overall resiliency of the system1.

References :=

ACI Multi-Pod White Paper - Cisco1

To configure an L3Out peering with the backbone network that must forward both unicast and multicast traffic, the two methods that should be used are:

Layer 3 routed port (Option A): This method involves configuring a physical port on the Cisco ACI leaf switch as a Layer 3 interface, which is suitable for routing unicast and multicast traffic.

Layer 3 routed subinterface (Option D): This method involves configuring a subinterface under a physical port, which allows for traffic segregation and routing over the same physical link, supporting both unicast and multicast traffic.

These methods ensure that the L3Out can handle the required traffic types and maintain proper routing with the backbone network.

https://www.cisco.com/c/en/us/solutions/collateral/data-center-virtualization/application-centricinfrastructure/

guide-c07-743150.html#_L3Out_sStatic_rRoutes

https://www.cisco.com/ c/en/us/td/docs/switches/datacenter/aci/apic/sw/4-x/L3-configuration/Cisco-APIC-Layer-3-Networking-Configuration-Guide-401/Cisco-APIC-Layer-3-Networking-Configuration-Guide-401_chapter_010010.html

The group of settings required to meet the requirements for workload migration where servers will physically terminate at the Cisco ACI, but their gateway must stay in the existing network, is:

L2 Unknown Unicast: Flood

L3 Unknown Multicast Flooding: Flood

Multi Destination Flooding: Flood in BD

ARP Flooding: Enable5

These settings ensure that the bridge domain is configured to handle unknown unicast and multicast traffic appropriately, and ARP flooding is enabled to allow for the resolution of IP addresses when the gateway is outside the fabric5.

https://www.cisco.com/c/en/us/td/docs/switches/datac enter/aci/apic/sw/migration_guides/migrating_existing_networks_to_aci.html