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Understanding ACI Hardware and Topologies

Chapter Description

ACI is designed to allow small and large enterprises and service providers to build massively scalable data centers using a relatively small number of very flexible topologies. In this sample chapter from CCNP Data Center Application Centric Infrastructure 300-620 DCACI Official Cert Guide, the author team details the topologies with which an ACI fabric can be built or extended.

This chapter covers the following topics:

ACI Topologies and Components: This section describes the key hardware components and acceptable topologies for ACI fabrics.

APIC Clusters: This section covers available APIC hardware models and provides an understanding of APIC cluster sizes and failover implications.

Spine Hardware: This section addresses available spine hardware options.

Leaf Hardware: This section outlines the leaf platforms available for deployment in ACI fabrics.

This chapter covers the following exam topics:

  • 1.1 Describe ACI topology and hardware

  • 6.1 Describe Multi-Pod

  • 6.2 Describe Multi-Site

ACI is designed to allow small and large enterprises and service providers to build massively scalable data centers using a relatively small number of very flexible topologies.

This chapter details the topologies with which an ACI fabric can be built or extended. Understanding supported ACI topologies helps guide decisions on target-state network architecture and hardware selection.

Each hardware component in an ACI fabric performs a specific set of functions. For example, leaf switches enforce security rules, and spine switches track all endpoints within a fabric in a local database.

But not all ACI switches are created equally. Nor are APICs created equally. This chapter therefore aims to provide a high-level understanding of some of the things to consider when selecting hardware.

“Do I Know This Already?” Quiz

The “Do I Know This Already?” quiz allows you to assess whether you should read this entire chapter thoroughly or jump to the “Exam Preparation Tasks” section. If you are in doubt about your answers to these questions or your own assessment of your knowledge of the topics, read the entire chapter. Table 2-1 lists the major headings in this chapter and their corresponding “Do I Know This Already?” quiz questions. You can find the answers in Appendix A, “Answers to the ‘Do I Know This Already?’ Questions.”

Table 2-1 “Do I Know This Already?” Section-to-Question Mapping

Foundation Topics Section


ACI Topologies and Components


APIC Clusters


Spine Hardware

7, 8

Leaf Hardware

9, 10

  1. An ACI fabric is being extended to a secondary location to replace two top-of-rack switches and integrate a handful of servers into a corporate ACI environment. Which solution should ideally be deployed at the remote location if the deployment of new spines is considered cost-prohibitive and direct fiber links from the main data center cannot be dedicated to this function?

    1. ACI Multi-Site

    2. ACI Remote Leaf

    3. ACI Multi-Tier

    4. ACI Multi-Pod

  2. Which of the following is a requirement for a Multi-Pod IPN that is not needed in an ACI Multi-Site ISN?

    1. Increased MTU support

    2. OSPF support on last-hop routers connecting to ACI spines

    3. End-to-end IP connectivity

    4. Multicast PIM-Bidir

  3. Which of the following connections would ACI definitely block?

    1. APIC-to-leaf cabling

    2. Leaf-to-leaf cabling

    3. Spine-to-leaf cabling

    4. Spine-to-spine cabling

  4. Which of the following are valid reasons for ACI Multi-Site requiring more specialized spine hardware? (Choose all that apply.)

    1. Ingress replication of BUM traffic

    2. IP fragmentation

    3. Namespace normalization

    4. Support for PIM-Bidir for multicast forwarding

  5. Which of the following options best describes border leaf switches?

    1. Border leaf switches provide Layer 2 and 3 connectivity to outside networks.

    2. Border leaf switches connect to Layer 4–7 service appliances, such as firewalls and load balancers.

    3. Border leaf switches are ACI leaf switches that connect to servers.

    4. Border leaf switches serve as the border between server network traffic and FCoE storage traffic.

  6. Which of the following statements is accurate?

    1. A three-node M3 cluster of APICs can scale up to 200 leaf switches.

    2. Sharding is a result of the evolution of what is called horizontal partitioning of databases.

    3. The number of shards distributed among APICs for a given attribute is directly correlated to the number of APICs deployed.

    4. A standby APIC actively synchronizes with active APICs and has a copy of all attributes within the APIC database at all times.

  7. Out of the following switches, which are spine platforms that support ACI Multi-Site? (Choose all that apply.)

    1. Nexus 93180YC-EX

    2. Nexus 9364C

    3. Nexus 9736C-FX line card

    4. Nexus 9396PX

  8. Which of the following is a valid reason for upgrading a pair of Nexus 9336PQ ACI switches to second-generation Nexus 9332C spine hardware? (Choose all that apply.)

    1. Namespace normalization for ACI Multi-Site support

    2. Support for 40 Gbps leaf-to-spine connectivity

    3. Support for CloudSec

    4. Support for ACI Multi-Pod

  9. True or false: The Nexus 93180YC-FX leaf switch supports MACsec.

    1. True

    2. False

  10. Which of the following platforms is a low-cost option for server CIMC and other low-bandwidth functions that rely on RJ-45 connectivity?

    1. Nexus 9336C-FX2

    2. Nexus 93180YC-FX

    3. Nexus 9332C

    4. Nexus 9348GC-FXP

2. ACI Topologies and Components | Next Section

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