QFX5120-48Y(M) switches are 25-Gigabit Ethernet small form-factor pluggable (SFP28) switches with 48 SFP28 ports and eight 100-Gbps quad small form-factor pluggable (QSFP28) ports. Each SFP28 port can operate as a native 25-Gigabit Ethernet port, a 10-Gigabit Ethernet port, or a 1-Gbps port based on the transceivers inserted.
EX4650 switches offer 48 25-Gigabit Ethernet ports that can operate at 1-Gbps, 10-Gbps, or 25-Gbps speed and support SFP, SFP+, or SFP28 transceivers; and 8 100-Gigabit Ethernet ports that can operate at 40-Gbps or 100-Gbps speed and support QSFP+ or QSFP28 transceivers.
However, by default, ports 0 to 47 are pre-configured to work only at 10G speeds and require modification of the chassis configuration to connect 1G or 25G transceivers.For EX4400, Auto-negotiation feature is not supported for EX4400-EM-4S extension module 4x10G (SFP+ & SFP ports).
This article shows how the configuration can be modified.
If you try connecting an SFP-T on QFX5120-48Y(M) or EX4650-48Y, it will appear in the show chassis hardware output but not as a valid interface:
show chassis hardware
show chassis hardware Hardware inventory: Item Version Part number Serial number Description Chassis XH12345ABCDE JNP48Y8C-CHAS Pseudo CB 0 Routing Engine 0 BUILTIN BUILTIN RE-QFX5120-48Y-8C FPC 0 REV 09 650-083242 XH12345ABCDE JNP48Y8C-CHAS CPU BUILTIN BUILTIN FPC CPU PIC 0 BUILTIN BUILTIN 48x25G-8x100G Xcvr 0 REV 01 740-038291 ABC0123 SFP-T Xcvr 1 REV 01 740-038291 CDE0123 SFP-T Power Supply 0 REV 04 740-070749 1A234567890 JPSU-650W-AC-AO Power Supply 1 REV 04 740-070749 1B345678901 JPSU-650W-AC-AO Fan Tray 0 fan-ctrl-0 0, Front to Back Airflow - AFO Fan Tray 1 fan-ctrl-0 1, Front to Back Airflow - A show interfaces terse Interface Admin Link Proto Local Remote gr-0/0/0 up up pfe-0/0/0 up up pfe-0/0/0.16383 up up inet inet6 pfh-0/0/0 up up pfh-0/0/0.16383 up up inet pfh-0/0/0.16384 up up inet <-----------No interfaces created bme0 up up bme0.0 up up inet 128.0.0.1/2 128.0.0.4/2 128.0.0.63/2 cbp0 up up dsc up up em0 up up
Also the following messages will be logged in the switch:
Jan 19 01:04:59 jtac-qfx5120-48y-8c fpc0 CMQFX: FPC0:PIC0:PORT0 Default (10g) config on port but XCVR doesn't support 10g speed. IFD creation skipped Jan 19 01:04:59 jtac-qfx5120-48y-8c fpc0 CMQFX: FPC0:PIC0:PORT1 Default (10g) config on port but XCVR doesn't support 10g speed. IFD creation skipped
Also the If you run the command "show interfaces terse | match <interface-name>", you will get the error device <interface-name> not found as per below:
user@switch> show interfaces terse ge-0/0/0 error: device ge-0/0/0 not found
CAUTION: If you face a problem running a Juniper Networks device that uses a third-party optic or cable, the Juniper Networks Technical Assistance Center (JTAC) can help you diagnose the source of the problem. Your JTAC engineer might recommend that you check the third-party optic or cable and potentially replace it with an equivalent Juniper Networks optic or cable that is qualified for the device.
You can find more information at EX4650 Network Cable and Transceiver Planning .
To convert the ports to connect 1G or 25G transceivers, use the following command from the chassis hierarchy. The speed configuration under the chassis can be applied only for quads (four ports) and not for single ports:
[edit chassis fpc fpc-slot pic pic-slot] user@switch# set port port-number speed speed
Example
set chassis fpc 0 pic 0 port 0 speed 1G <- 0 to 3 set chassis fpc 0 pic 0 port 12 speed 1G <- 12 to 15 set chassis fpc 0 pic 0 port 16 speed 1G <- 16 to 19
After adding the configuration, the interfaces will display:
set chassis fpc 0 pic 0 port 0 speed 1G show interfaces terse Interface Admin Link Proto Local Remote ge-0/0/0 up up ge-0/0/0.0 up up eth-switch <-------Interface is now created. gr-0/0/0 up up pfe-0/0/0 up up pfe-0/0/0.16383 up up inet inet6 pfh-0/0/0 up up pfh-0/0/0.16383 up up inet pfh-0/0/0.16384 up up inet ge-0/0/1 up up ge-0/0/1.0 up up eth-switch <-------Interface is now created. bme0 up up
Note: If the connected SFP is defective or unsupported, the configuration may commit but the interface may not be created or report unexpected behavior. It is recommended that you use optical transceivers and connectors purchased from Juniper Networks with your Juniper Networks device.
EX4400 EX4400-EM-4S extension module, QFX5120-48Y(M) and EX4650-48Y do not support auto-negotiation for 1 Gigabit fiber SFP transceivers. In such cases, it is recommended to disable auto-negotiation on the remote end device.QFX5120-48Y(M)/EX4650-48Y switches with 1-gigabit copper SFP transceiver support auto-negotiation, as the physical layer within the transceiver handles auto-negotiation.
Example on how to disable auto-negotiation in Junos OS:
set interfaces ge-0/0/0 speed 1g set interfaces ge-0/0/0 link-mode full-duplex set interfaces ge-0/0/0 ether-options no-auto-negotiation
See Port Settings for more information.
2020-08-06: Minor, non-technical edit
2021-09-20: Added EX4650, consideration on auto-negotiation and general comments on SFPs as per Juniper's public pages
2021-12-31: Changed QFX5120-48Y to QFX5120-48Y(M) to avoid confusion 2023-05-08: KB modified, added extension module for EX4400 as affected.2023-05-23: Minor change made. 2024-04-19: Minor change on symptom.