Question about using QSFP+ ports for ISC links on Summit X670-G2's if stacking is involved.

[MartinS]

I built a new MLAG pair of 5520-48W's recently, and when I created the ISC link, I wanted to use the QSFP+ ports, but the 5520's would not let me. In the end I got it working by disabling stacking support on the switches. It was fine because they were individual switches and not stacked. 

I am now tasked with building two MLAG pairs which will also be created as two stacks: 

This time I've had to enable stacking support obviously, but if I'm going to want to use those QSFP+ ports for regular data VLANs I'll need to disable stacking support, right? Is there another way around this? 

[Chris_H]

There are  different native stacking-methods for the x670-G2: V320, V160 and V80 stacking.

V320 stacking uses all 4 QSFP ports (49,53,57 and 61), while V160 and V80 stacking uses only ports 57 and 61, leaving QSFP+ ports 49 and 53 available for data. See https://extremeportal.force.com/ExtrArticleDetail?an=000083152

The x460-G2 only supports V160 stacking when using the VIM-2Q extension module, and not V320 or V80.

[MartinS]

Hi Chris, 

I am not referring to Native stacking here sorry, I should have explained. I know that the X670-G2 actually supports 4 different methods of stacking: SummitStack-V, SummitStack-V80, SummitStack-V160, and SummitStack-V320. The X460-G2 supports a total of 3 different methods of stacking: SummitStack, SummitStack-V  or SummitStack-V160. I'm using SummitStack-V to connect these units together, which is an Alternate method, not a Native method.  On the Summit X670-G2: Front ports 47 and 48 are used for SummitStack-V. On the Summit X460-G2: ports 51 and 52 are designated for SummitStack-V.  I have specified the stacking method as Alternate on all these switches and they have joined up absolutely fine as a stack. I'm just not sure if  the QSFP+ ports on the X670-G2, which are still un-used by me at this point, will still work as normal data ports in this case? 

[Chris_H · Accepted solution]

Hi Martin,

Thanks for the clarification. Yes, when alternate stacking is selected as stack-port selection on the x670-G2, then all 4 QSFP+ ports are set to "data" in the ASIC and not to "stacking", so you can use all of them for regular traffic.