Example Configuration: Building the Virtual-Chassis using 100G between QFX5110-48S and QFX5110-32Q

Example Topology:

+---------------+                 +---------------+
|               |50            28 |               |
| QFX5110-48S   +-----------------+ QFX5110-32Q   |
|               |                 |               |
+---------------+                 +---------------+

Note: QFX5110-32Q switch ports from 28 to 31 can be operated as 100G. However, by default, these ports will not operate at 100G speed.

root@jtac-qfx5110-32q-r2023# run show chassis hardware
Hardware inventory:
Item             Version  Part number  Serial number     Description
Chassis                                WT3718220096      QFX5110-32Q
CB 0
Routing Engine 0          BUILTIN      BUILTIN           RE-QFX5110-32Q
FPC 0            REV 08   650-077245   WT3718220096      QFX5110-32Q
  CPU                     BUILTIN      BUILTIN           FPC CPU
  PIC 0                   BUILTIN      BUILTIN           32x 40G-QSFP
    Xcvr 0       REV 01   740-043308   UZ30ELX           QSFP+-40G-LR4
    Xcvr 1       REV 01   740-043308   UZ30L1S           QSFP+-40G-LR4
    Xcvr 28      REV 01   740-061001   1PC422083AD       QSFP28-100G-CU3M

root@jtac-qfx5110-32q-r2023# run show interfaces terse
Interface               Admin Link Proto    Local                 Remote
et-0/0/0                up    down
et-0/0/0.0              up    down inet
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
et-0/0/1                up    down
et-0/0/1.0              up    down inet      <-- et-0/0/28 was not created
bme0                    up    up
bme0.0                  up    up   inet     128.0.0.1/2
                                            128.0.0.4/2

root@jtac-qfx5110-32q-r2023#run request virtial-chassis vc-port set pic-slot 0 port 28
Port conversion initiated,  use show virtual-chassis vc-port to verify

{master:0}[edit]
root@jtac-qfx5110-32q-r2023# run show virtual-chassis vc-port
localre:
--------------------------------------------------------------------------
Interface   Type              Trunk  Status       Speed        Neighbor
or                             ID                 (mbps)       ID  Interface
PIC / Port
0/28        Configured         -1    Down         100000

Even if we create this port as VC-Port, the port will remain as down. In order to bring the 100g interface up in QFX5110-32Q, change the chassis system-mode to flexi using command below:

root@jtac-qfx5110-32q-r2023# run request chassis system-mode flexi-pic-mode
System-mode has changed. This will restart PFE. <-- changing the mode will restart the PFE

Notes:
Flexi-pic mode (from Junos OS Release 17.2R1 up to Junos OS Release 18.1R1):

Ports 0 through 19 of the switch are configured for 40-Gigabit Ethernet and can be channelized to 4 independent 10-Gigabit Ethernet ports.
Ports 20 though 27 are disabled.
Ports 28 through 31 are configured as 100-Gigabit Ethernet.

After changing the mode to flexi-pic-mode, the port is operating at 100g and VC-port also came up and Virtual-Chassis formed.

root@jtac-qfx5110-32q-r2023> show interfaces terse
Interface               Admin Link Proto    Local                 Remote
et-0/0/0                up    down
et-0/0/0.0              up    down inet
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
et-0/0/1                up    down
et-0/0/1.0              up    down inet
et-0/0/28               up    up          <-- port came up 
et-0/0/28.16386         up    up


root@jtac-qfx5110-32q-r2023> show chassis hardware
Hardware inventory:
Item             Version  Part number  Serial number     Description
Chassis                                WT3718220096      QFX5110-32Q
CB 0
Routing Engine 0          BUILTIN      BUILTIN           RE-QFX5110-32Q
FPC 0            REV 08   650-077245   WT3718220096      QFX5110-32Q
  CPU                     BUILTIN      BUILTIN           FPC CPU
  PIC 0                   BUILTIN      BUILTIN           32x 40G-QSFP
    Xcvr 0       REV 01   740-043308   UZ30ELX           QSFP+-40G-LR4
    Xcvr 1       REV 01   740-043308   UZ30L1S           QSFP+-40G-LR4
    Xcvr 28      REV 01   740-061001   1PC422083AD       QSFP28-100G-CU3M

root@jtac-qfx5110-32q-r2023> request virtial-chassis vc-port set pic-slot 0 port 28
Port conversion initiated,  use show virtual-chassis vc-port to verify

root@jtac-qfx5110-32q-r2023> show virtual-chassis vc-port
localre:
--------------------------------------------------------------------------
Interface   Type              Trunk  Status       Speed        Neighbor
or                             ID                 (mbps)       ID  Interface
PIC / Port
0/28        Configured          1    Up           100000       vcp-255/0/50

root@jtac-qfx5110-32q-r2023> show virtual-chassis status
Preprovisioned Virtual Chassis
Virtual Chassis ID: 031c.393a.51dd
Virtual Chassis Mode: Enabled
                                                Mstr           Mixed Route Neighbor List
Member ID  Status   Serial No    Model          prio  Role      Mode  Mode ID  Interface
0 (FPC 0)  Prsnt    WT3718220096 QFX5110-32Q    129   Master*      N  VC   1  vcp-255/0/50                                                                          
1 (FPC 1)  Prsnt    WS3718310286 QFX5110-48S-4C 129   Backup       N  VC   0  vcp-255/0/28

Knowledge Base