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Stacking Links question

Trusted Contributor

Stacking Links question

Gianluca asked:





1 easy question for you, regarding Stacking Link configuration in VC:


When in the same enclosure we have more than 2 VC modules they must be  interconnected between them (vertical connection).

Is this a “MUST” or is a “best practice”?


Like this:






Reply from Aleksandar:

Yes, you must stack the modules inside the enclosure. Otherwise the domain will be in degraded status and you might have issues in the long run.


Input from Andrea:

From the VC Install Guide:


Recommended stacking connections

Stacking links are used to add VC-Enet modules into a Virtual Connect domain. This feature enables all

Ethernet network controllers on all servers in the Virtual Connect domain to have access to


Virtual Connect automatically detects when one VC-Enet module port is connected to another VC-Enet

module port within the domain and changes the port ID indicator to amber.

All VC-Enet modules within the Virtual Connect domain must be interconnected   ß ß ß ß ß ß ß ß

Any combination of 1-Gb and 10-Gb cables can be used to interconnect the modules. However, the following table provides

recommended configurations for two, four, six, or eight VC-Enet modules. A 10-Gb stacking link is already

provided on the enclosure midplane for horizontally adjacent VC-Enet modules (bays 1 and 2, 3 and 4, 5

and 6, or 7 and 8 of the c7000 enclosure, or bays 1 and 2 or 3 and 4 of the c3000 enclosure).


No-stacking solutions are not supported.


And from Lawrance:

One of the reasons why both left and right side VC most be connected vertically is when you need to apply VC firmware updates to the 4 modules.


If you only had one of the two vertical connections in place, the VCM in the primary module will get disconnected from the VC modules that are stacked when the one module that connects the top to the bottom module is reset.  This could result in an unstable VC domain.  Having both pairs of VC modules connected via the stacking cables mean that the VCM will always have a communication path between the top and bottom row of VC modules.




Hope this helps.