vCenter, How is connected to ACI via leaf

[TomMik]

Hi Everyone,

Maybe this topic was somewhere here already but I cannot find any information so I am hoping that you will help me some way.

I have vCenter integrated with APIC and I check everything, have IP etc.... but one thing which I cannot establish.

We had issue with APIC and VMM  so, I raised case with Cisco TAC and I was ask question as follow:

Could you give on which leaf/interface is connected the vcenter ? >>> I have no clue how this can be check so, I would appreciate some help or advise how this could be checked.

Thank you 

Tom

[RedNectar]

Hi @TomMik ,

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Could you give on which leaf/interface is connected the vcenter ?

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Before you can determine this, you need to know how the APIC communicates with vCenter - I've outlined 3 different ways below, and of these, only one actually has vCenter connected to a leaf!!

BUT if i assume that vCenter IS attached to a leaf, this is how you would go about finding the leaf/interface that it is attached to

1. Find the MAC address of vCenter.  Let's say it is 0050.5684.63ef 
2. Open an ssh session on the APIC and issue a
   fabric <lowestLeafId>-<largestLeafId> show mac address-table address 0050.5684.63ef  command

apic1# fabric 1201-1202 show mac address-table address 0050.5684.63ef
----------------------------------------------------------------
 Node 1201 (Leaf1201)
----------------------------------------------------------------
Legend:
	* - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MAC
	age - seconds since last seen,+ - primary entry using vPC Peer-Link,
	(T) - True, (F) - False
   VLAN     MAC Address      Type      age     Secure NTFY Ports/SWID.SSID.LID
---------+-----------------+--------+---------+------+----+------------------
* 105      0050.5684.63ef    dynamic      -       F    F    eth1/29

Three ways ACI can communicate with vCenter

You can have vCenter communicate with the ACI APIC using the out-of-band (OOB) management VRF or the inband management VRF

This is decided when adding the vCenter Controller to the vCenter VMM Domain - if you leave the choice of Management EPG blank, then communication will be via the OOB VRF I believe (I could be wrong - it may be determined via the choice of APIC Connectivity Preference defined in System > System Settings >> APIC Connectivity Preference)

The point is, if you use OOB to communicate with vCenter, then vCenter does NOT have to be connected to ANY leaf anywhere - as is the case in our lab.

Note that vCentre is NOT connected to ANY leaf in the diagram above, and the APIC communicates with vCenter directly using the OOB management network.

However, if you use inband management, you have more flexibility.  In this case, you have two choices - I documented these back in 2016. (I actually documented 3 methods - but PLEASE don't use a L2Out)

1. via an EPG in the mgmt Tenant, where vCentre IS attached to a Leaf
   Source: https://rednectar.net/?attachment_id=2500
2. via a L3Out in the mgmt Tenant, where again, vCenter is NOT attached to any leaf
   Source: https://rednectar.net/?attachment_id=2601

You may find this answer I wrote years ago helpful too, but it deals with a more complicated case involving UCS.

[TomMik]

Hi Chris,

This is very helpful, really appreciate your help on this one