ACI leaf and FEX question

[Madura Malwatte]

I have some questions about connectivity between leaf switches and FEX in ACI deployments.

1. For example if using and N9K-C93180YC-EX with Nexus 2332TQ, the leaf switch supports 6 QSFP ports. Now if I hypothetically have 6 spines, all the ports on the leaf switch will be used for spine uplink connectivity (1 link to each spine), this leaves me no QSFP ports for downlink to the fex module (this fex only supports QSFP ports as fabric interfaces). Is this correct? Or would I have to use break out cable and connect the fex QSFP uplinks to leaf 4 x 10G sfp ports via the breakout adapter?

2. Is this document accurate in regards to FEX compatibility with ACI - https://www.cisco.com/c/en/us/support/docs/cloud-systems-management/application-policy-infrastructure-controller-apic/200529-Configure-a-Fabric-Extender-with-Applica.html

[jose.tamayo.segarra]

Hello,

Regarding question 1), you can converter up to 4 of the 6 QSPF uplinks on the switch. Here is a document on how to perform this conversion. https://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/2-x/L2_config/b_Cisco_APIC_Layer_2_Configuration_Guide/b_Cisco_APIC_Layer_2_Configuration_Guide_chapter_0100.pdf. WARNING: I have not performed this procedure myself, but apparently it needs the Leaf to be rebooted.

On question 2), the referenced page uses an old version of APIC, but the steps remain similar. However, this blog entry seems more helpful to me to properly structure your Access Policies for FEX: https://tabtabblog.wordpress.com/2017/10/10/configuring-fex-in-aci/

Hope this helps.