configuring vlans on both fabrics or single

[e.nieuwstad]

I have been working on some scripts to configure a number of vlans on a UCS environment. In the end I had configured the same vlan (hr) on

• the A fabric fabric/lan/A/hr
• the B fabric fabric/lan/B/hr
• on both fabric fabric/lan/hr

So I have three objects where the first two imply the same as the last one. I would think it more logical that if you configure a vlan on both fabrics it would create two objects one as fabric/lan/A/hr and one as fabric/lan/B/hr in stead of creating a single object fabric/lan/hr. Not sure what the consequences are as I haven't configured it live but it looks weird.

[Jeremy Waldrop]

you should only create the VLANs as Common/global

http://www.cisco.com/en/US/docs/unified_computing/ucs/sw/gui/config/guide/2.0/b_UCSM_GUI_Configuration_Guide_2_0_chapter_010000.html#task_991AE84D88CB4808A8F9CD6DEC90147F

[e.nieuwstad]

I know how I created it and that I should not do it like this. I am just surprised the systems allows me to configure such an possible ambigious configuration.

[Robert Burns]

The global and fabric VLANs are mutually exclusive. 

This allows you to either create the same named VLAN (but different VLAN IDs) on each fabric, or different named VLANs (same VLAN ID) on each fabric.

I don't know of many practical use cases myself, and as Jeremy said, the common practice is to use global VLANs, unless you perhaps have a NAS single attached to one FI. 

It's just an option for flexibility.

Regards,

Robert