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[QFX/EX] Configuring 1G and 25G ports on QFX5120-48Y and EX4650-48Y

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Article ID: KB35439 KB Last Updated: 20 Sep 2021Version: 3.0
Summary:

QFX5120-48Y 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.

This article shows how the configuration can be modified.

Symptoms:

If you try connecting an SFP-T on QFX5120-48Y or EX4650-48Y, it will appear in the show chassis hardware output but not as a valid interface:

show chassis hardware                                                                                       
Hardware inventory:                                                                                                                         
Item             Version  Part number  Serial number     Description                                                                        
Chassis                                XH3719370381      JNP48Y8C-CHAS                                                                      
Pseudo CB 0                                                                                                                                 
Routing Engine 0          BUILTIN      BUILTIN           RE-QFX5120-48Y-8C                                                                  
FPC 0            REV 09   650-083242   XH3719370381      JNP48Y8C-CHAS                                                                      
  CPU                     BUILTIN      BUILTIN           FPC CPU                                                                            
  PIC 0                   BUILTIN      BUILTIN           48x25G-8x100G                                                                      
    Xcvr 0       REV 01   740-038291   I100254           SFP-T                                                                              
    Xcvr 1       REV 01   740-038291   E066957           SFP-T                                                                      
Power Supply 0   REV 04   740-070749   1F189203760       JPSU-650W-AC-AO                                                                    
Power Supply 1   REV 04   740-070749   1F189203434       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

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.

Solution:

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.

QFX5120-48Y/EX4650-48Y does not support auto-negotiation when a 1-gigabit fiber SFP transceiver is plugged in. In such cases, it is recommended to disable auto-negotiation on the remote end device. But, QFX5120-48Y/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.

Modification History:
  • 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

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