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QSA28 port config on Z9264F
In a Z9264F device (OS 10.5.2.7), intending to have 10G/SFP+ ports (for 10G-SR, 10G-LR and SFP+ DAC's connections), QSA28 adapters were used to transform QSFP28(100G) ports into SFP+(10G) ports.
This QSA28's approach is also indicated in the dell-networking-optics-spec-sheet.pdf
Without any other info, we are realizing that, using the profile that allows breakout-cables (10g-4x), where for every pair of QSFP28 ports one of the QSFP28 ports is disabled (instead of having the 64 QSFP28 ports, there would be only 32 ports):
Dell EMC SmartFabric OS10 User Guide Release 10.5.2
Dell EMC SmartFabric OS10 User Guide Release 10.5.1
We couldn't find any more information about the configuration of QSA28's and this was the only profile that “raised” the 10G port on the QSA28.
This is all weird for a Z9264F for several reasons:
1. The profile to use for the QSA28 is the same as for 4x10g breakout, but it is not a sub-interfacing of a port (breakout), but a single-interface (it should still be port no. “ xx”, but not 100G, now 10G);
2. The port-group profile will be for sets of 2 ports, disabling 1 of them when changing the profile… at most it could force to have the same profile in both and so stay eg the 2 ports at 10G;
3. If this limitation is confirmed, it means a 50% loss in the modularity of the equipment, which is extremely damaging for equipment of this range/performance.
In short:
We need to configure ports with QSA28 to use SFP+/10G transceivers without disabling other ports on the equipment... does anyone have more information about configuring ports with QSA28 or how to overcome this limitation?
Thanks.
DELL-Josh Cr
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December 9th, 2021 16:00
Hi Rui,
It does look like this is the limitation since it supports a maximum of 128 ports and 32X4 would hit this limit. https://dell.to/3oHGNWC
rui.araujo
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December 10th, 2021 01:00
Hi Josh.
Apreciated for the feedback.
The 128 port limitation on the equipment is understood... intended when using breakout modules/cables (that would transform each port into four sub-ports)... but NOT when using a QSA28, that transforms a single port into a single port, not into four... therefore, at the most, the 64x Q28 ports would still be 64x ports when using QSA28 (but S28 interface type).
The other matter is the configuration mode... as a QSA is NOT a breakout (split), so, you won't be defining sub-interfaces (or lanes) on the transceiver... it should be only a matter of speed limitation on the main port (that instead of supporting Q28, would only support S28 connections/speeds). And nothing appears on the documentation on how to configure the port when using QSA... as I refered, the interface link came up using the breakout mode, but it should not be configured as a breakout, as it is not.
Thanks.
Rgds.
DELL-Erman O
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December 10th, 2021 02:00
Hi, Thanks for the detailed reply. I researched but I could not find a direct document or instance on how to configure it with the QSA28 adapter as you looking for. This switch has 64 ports of 100GbE QSFP28 or up to 128 ports of 10/25/40/50GbE ports using breakout cables. But frankly, I have not seen an example of its use with the QSA28 adapter. Please keep updating this thread if you overcome limitation. it will be informative in the community if you share your experiences by updating this topic.
DELL-Tim G
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December 23rd, 2021 07:00
Hi Rui,
please see a QSFP28 port as a "quad SFP28" port which means it is electrically combining 4x 25GbE lanes to form one 100GbE link.
What a QSA is doing it is just "grabbing" one of these 4 lanes and routing it to a SFP compatible slot.
The other 3 lanes will be unsusable.
I hope this explains why you need to configure a port as a 4x25G or 4x10G breakout port when using the QSA (QSFP to SFP adapter).
Cheers,
Tim
rui.araujo
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December 28th, 2021 09:00
Hi Tim.
Appreciated for the insight on how the QSA works... as we didn't find any info on it.
Although, as it is a single-lane adapter, and the other lanes are unusable, the QSA config mode should be different than the breakout (split) mode, and therefore, the other Q28 port associated shouldn't be disabled, as in this switch, if all the Q28 were populated with QSA's, it would only had 64 ports of S28 transceivers, not exceeding the 128 limit.
Thanks.
Rgds.