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350-601 · Question #386

Refer to the exhibit. SVR-A in EPG-A/BD-A fails to reach SVR-B in EPG-B/BD-B. Which two conditions should be verified to analyze the traffic between the two EPGs? (Choose two.)

The correct answer is A. A contract exists between EPG-A and EPG-B and allows the traffic. C. SVR-B is learned as an endpoint in EPG-B from Node-112. When two endpoints in different Endpoint Groups (EPGs) within Cisco ACI fail to communicate, it is crucial to verify the existence of a contract allowing traffic between those EPGs and confirm that both endpoints are correctly learned within their respective EPGs.

Network

Question

Refer to the exhibit. SVR-A in EPG-A/BD-A fails to reach SVR-B in EPG-B/BD-B. Which two conditions should be verified to analyze the traffic between the two EPGs? (Choose two.)

Exhibit

350-601 question #386 exhibit

Options

  • AA contract exists between EPG-A and EPG-B and allows the traffic.
  • BLimit Endpoint Learning is disabled on the bridge domain for EPG-B.
  • CSVR-B is learned as an endpoint in EPG-B from Node-112.
  • DEPG-A and EPG-B are excluded from the preferred group.
  • EThe bridge domain for EPG-B floods ARP packets.

How the community answered

(57 responses)
  • A
    77% (44)
  • B
    4% (2)
  • D
    14% (8)
  • E
    5% (3)

Why each option

When two endpoints in different Endpoint Groups (EPGs) within Cisco ACI fail to communicate, it is crucial to verify the existence of a contract allowing traffic between those EPGs and confirm that both endpoints are correctly learned within their respective EPGs.

AA contract exists between EPG-A and EPG-B and allows the traffic.Correct

In Cisco ACI, communication between endpoints in different EPGs is governed by contracts. If SVR-A and SVR-B are in different EPGs (EPG-A and EPG-B), a contract must exist between them that permits the specific traffic flow (e.g., ICMP, HTTP) for communication to succeed.

BLimit Endpoint Learning is disabled on the bridge domain for EPG-B.

Limit Endpoint Learning (also known as Unicast Routing) controls whether the Bridge Domain performs IP learning; disabling it would not directly prevent traffic, and it's generally enabled for IP routing.

CSVR-B is learned as an endpoint in EPG-B from Node-112.Correct

For any endpoint to communicate within or across EPGs, it must first be learned by the ACI fabric. Verifying that SVR-B is learned as an endpoint in EPG-B from its connected leaf (Node-112) confirms the fabric is aware of the server's location and can properly forward traffic to it.

DEPG-A and EPG-B are excluded from the preferred group.

Whether EPG-A and EPG-B are excluded from a preferred group primarily affects contract enforcement within a VRF, not necessarily the fundamental ability of a contract to allow traffic.

EThe bridge domain for EPG-B floods ARP packets.

While ARP flooding is necessary for endpoints to learn each other's MAC addresses within the same broadcast domain, this is an underlying mechanism; the primary issues for inter-EPG communication failure are typically contracts and endpoint learning.

Concept tested: Cisco ACI inter-EPG communication troubleshooting

Source: https://www.cisco.com/c/en/us/td/docs/aci/apic/5x/troubleshooting/cisco-aci-troubleshooting-guide-50.html

Topics

#Cisco ACI#EPG Communication#Contracts#Endpoint Learning

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