Troubleshooting Connectivity Issues between VMM Domain and EPG in ACI

Why the Host Cannot Communicate with Default Gateway on EPG

Question

When you add a VMM domain to an EPG in ACI, it seems that the host that is connected to the APG-port group cannot communicate with its default gateway that is configured on the EPG.

Which reason for this behavior is true?

Answers

Explanations

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A. B. C. D.

D.

When a VMM domain is added to an EPG (Endpoint Group) in the ACI (Application Centric Infrastructure), the host that is connected to the EPG-port group may not be able to communicate with its default gateway configured on the EPG. The reason for this behavior can be due to several factors, as described below:

A. The configuration is not committed: If the configuration changes are made but not committed, then the changes will not be applied, and the host will not be able to communicate with its default gateway. Therefore, it is essential to commit the configuration changes once the necessary changes are made.

B. A contact blocks the communication from the host to its default gateway: It is possible that a contract may be blocking communication from the host to its default gateway. A contract defines the allowed communication between EPGs, and if the contract is not configured correctly, it can block communication between EPGs.

C. The VLAN is blocked in the fabric interconnect: The VLAN to which the EPG belongs may be blocked in the fabric interconnect, preventing communication between the host and its default gateway. To resolve this issue, the VLAN should be allowed on the uplink from the fabric interconnect to the Cisco UCS.

D. The VLAN to which the EPG belongs is not configured on the uplink from the fabric interconnect to the Cisco UCS: If the VLAN to which the EPG belongs is not configured on the uplink from the fabric interconnect to the Cisco UCS, then the host will not be able to communicate with its default gateway. To resolve this issue, the VLAN should be allowed on the uplink from the fabric interconnect to the Cisco UCS.

In conclusion, several reasons can lead to the host not being able to communicate with its default gateway when a VMM domain is added to an EPG in ACI. Therefore, it is necessary to check all the possible factors mentioned above to resolve this issue.