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UCS VLAN Count and ACI

joel.cason
Level 1
Level 1

The max VLAN count per FI looks to be 32000, and 64000 when in optimized mode.  With ACI we have a LOT of VLANs on some vNICs so we are approaching the 32000 limit.

 

Is there any downside to enabling the VLAN port count optimization?  And will it conflict in some way with ACI?  Looking at the UCSM guide it just seems like a positive thing to enable (less CPU utilization, more VLANs available) but it is not the default setting.

 

Finally, is this a disruptive setting to enable or disable?  I know it can't be disabled if you have more than 32000 VLANs.  

4 Replies 4

Qiese Dides
Cisco Employee
Cisco Employee

Hi Joel,

 

VLAN port count optimization enables mapping the state of multiple VLANs into a single internal state. When you enable the VLAN port count optimization, Cisco UCS Manager logically groups VLANs based on the port VLAN membership. This grouping increases the port VLAN count limit. VLAN port count optimization also compresses the VLAN state and reduces the CPU load on the fabric interconnect. This reduction in the CPU load enables you to deploy more VLANs over more vNICs. Optimizing VLAN port count does not change any of the existing VLAN configuration on the vNICs.

 

What you will see though is an increase in memory usage. This should not impact production when enabling. However, I always recommend to do wide spread changes in a maintenance window if possible.

 

Hope this helps,

 

Qiese Dides

Also, you most likely will not hit this bug but for anyone else that is reading this thread and is thinking about enabling VLAN port count optimization please be careful for the following bug:

 

https://bst.cloudapps.cisco.com/bugsearch/bug/CSCuf35678/?reffering_site=dumpcr

Thank you for the information.

 

So is it safe to say that VLAN port optimization does not affect anything upstream, including ACI?  From the upstream switch perspective, nothing will appear to change?

Hi Joel,

 

Yes it would be safe to assume this but as I mentioned it's always best to do any major changes in a maintenance window. However, just a heads up when you enable Vlan Port Optimization you will not be able to disable it if your amount of VLANs created go over the limit once you enabled it.

 

Hope this solution helps.

 

Qiese Dides

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