APIC Connections to Leafs

[CiscoIPMAN]

Does the APIC need a direct connection to each leaf switch? From the documentation it seems that way but i also see that the APIC has a VIC card that needs to connect to the leaf to be able to detect the leaf switch. The VIC has only 4 ports which to me seems to limit the amount of leaf switches you can connect to the APIC. 

Thanks for any help

[Sergiu.Daniluk]

Hi @CiscoIPMAN 

For the Fabric discovery to happen, the APIC needs minimum one connection to one Leaf. That one connected leaf will be discovered, and once it is registered in APIC, the spines will be discovered. Once the spines are registered, the rest of the leaf switches will be discovered.

You can connect the APIC to two different leaf switches to have connectivity to fabric in case one of them fails.

NOTE: in case of APIC-M3/L3 DO NOT use all 4 VIC ports. That is becaus port-1 and port-2 is one pair, corresponding to eth2-1 on APIC and port-3 and port-4 is another pair, corresponding to eth2-2 on APIC. Only one connection is allowed for each pair. For example, you can connect one cable to either port-1 or port-2, and connect another cable to either port-3 or port-4 (once again, do not connect two cables on any pair).

In other words, you can only connect your APIC to maximum 2 Leaf switches.

Stay safe,

Sergiu

[CiscoIPMAN]

Sergiu,

Thanks for the response. If I understand correctly, 

The APIC would connect to the leaf (using only 1 port in the pair eth-1 and eth-2). The leaf connects to the spine. When the APIC sees the leaf it gets registered. Once the leaf is registered i can register the spine switches. From this point on any future leaf switches that I connect to the spine the APIC will see them and I can register the added leaf switches?

Is that correct?

Thank you

[Robert Burns]

Correct.  This is all documented in the installation guide.   https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/hw/aci_hig/guide/b_aci_hardware_install_guide/b_aci_hardware_install_guide_chapter_011.html#task_C52F592F15B142EB99C96D52AF628E38

Robert