topic Re: X690 and long distance stacking in ExtremeSwitching (EXOS/Switch Engine)

X690 and long distance stacking

Charles2004 — Mon, 07 Sep 2020 03:18:51 GMT

Hi community

I have found i user guide that for stacking this switch supports 61 and 69 data ports and also that only QSFP28 DACs with lenght up to 5m can be used .

Does it mean that stacking for longer distances is not supported ?

I would like to stack two X690 located on two seperated Data Centers with at least 4 x40G links or other.

Is it supported on this model ?

I would appreciate any help

Best regards

Karol

Re: X690 and long distance stacking

Necheporenko__N — Mon, 07 Sep 2020 14:51:40 GMT

Hello Karol,

That 5m limitation is related to passive DAC cables, in your case you need to use active optic cables (AOC) which don’t have such distance limitation.

Best Regards,

Nikolay

Re: X690 and long distance stacking

Stefan_K_ — Mon, 07 Sep 2020 16:05:09 GMT

Well they don’t have “such” an distance limitation, but they do have a limitation, or am I wrong? According to the Datasheet the following maximum lengths apply to AOC cables:

20m for 100G
100m for 40G

A possibility would be SummitStack-V (or Alternate Stacking) but X690 doesn’t support this.

Charles, do you really want to stack theses switches? Personally I don’t like to stack central Datacenter switches (if there is an logical error, the whole stack is affected. And also if you do a firmware upgrade the whole stack will be down)
If you need to create an LAG from another Switch or Server to those X690s, think about MLAG instead of stacking. Just a hint. 🙂

Edit: I have to correct myself: Here it is described that Stacking via QSFP-SR4, LR4, CWDM4 and PSM4 is indeed working. But AOC would still not work over greater distances.

Best regards
Stefan

Re: X690 and long distance stacking

Charles2004 — Tue, 08 Sep 2020 03:06:57 GMT

Hi Nikolay and Stefan

Thank You for your hints and explanations. I would think over about MLAG, I like stacking bacause of simplicity although I know that MLAG has some advantages.

Can I use more ports for stacking then 61 and 69 ?

Regards

Karol

Re: X690 and long distance stacking

Stefan_K_ — Tue, 08 Sep 2020 03:13:31 GMT

Hi Charles,

I see. 🙂 Stacking is of course fine if you are aware of the disadvantages.
Why do you want to use more/other ports than 61/69? These links state that 61 and 69 are the only stacking ports:
https://documentation.extremenetworks.com/summit/GUID-2409A08C-9642-4245-9DB1-D7893DA1662F.shtml

https://documentation.extremenetworks.com/summit/GUID-B257AC27-28E6-4FB6-B785-86BBBB8C34A6.shtml

Best regards
Stefan

Re: X690 and long distance stacking

Charles2004 — Tue, 08 Sep 2020 03:30:30 GMT

Hi Stefan

I just wanted to be sure

Thank You for answer and fast help 🙂

Best regards

Karol