Mailing List Archive

QSA28 adapter in QFX5120-32C
Has anyone managed to get a 25G transceiver to work in a QFX5120-32C
switch with a QSA28 adapter, i.e, an adapter from QSFP28 to SFP28? If
so, what brand and model, what Junos version, and what configuration
magic did you need?

We have tried both an adapter from SmartOptics, and one from Dell,
but the switch doesn't seem to recognize it as a 25G transceiver at
all. The channelized interfaces (et-0/0/0:[0-3]) don't show up, only
a non-channelized interface (et-0/0/0), and the switch says it has a
speed of 40 Gbit/s.

The transceivers themselves (also from SmartOptics) seem to work, or
are at least *recognized*, when we put them in QFX5120-48Y switches,
but those have native SFP28 ports, so we are not using an adapter

QSA adapters for putting a 10G transceiver into it (i.e. not QSA28),
works without any problems in the switch, and likewise does break-out
DAC cables to give us 4×25G from each QSFP28 port.

We have configured the ports with

chassis {
fpc 0 {
pic 0 {
port 0 { channel-speed 25g; }
port 1 { channel-speed 25g; }
port 2 { channel-speed 25g; }

We have also tried "speed 100g" instead of "channel-speed 25g", as
well as no speed configuration at all, to no avail.

We have tested the QSA28 adapter in a Dell Z9100 switch as well, and
it seems to be OK with the adapter, and recognizes the transceiver as
25Gbase-LR (but then thinks it is not Dell qualified, and refuses to
use it, but the adapter itself seems OK).

Junos version 23.2R1-S1.6, but we have also tried 22.2R2-S1.5 (which
the switch arrived pre-installed with) and 22.4R2-S2.6 (which seems
to be the one with latest release date).

SmartOptics says they get their adapter to work in a PTX10001-36MR,
if you configure it with

interfaces {
et-0/1/4 {
number-of-sub-ports 4;
speed 25g;

but that syntax is not accepted by Junos on QFX5120 (I suppose it is
specific to Junos Evolved).

Thomas Bellman, National Supercomputer Centre, Linköping Univ., Sweden
"We don't understand the software, and sometimes we don't understand
the hardware, but we can *see* the blinking lights!"