Configure a Virtual Chassis on Juniper QFX5100-48S-6Q

Configuring a Virtual Chassis (VC) in Junos can look daunting at first, but taken step by step it is straightforward. This is how I configure a two-member VC on Juniper QFX5100-48S-6Q switches.

Find the serial numbers

A preprovisioned VC is defined by the serial number of each member. Mine start with VF:

greg@SWITCH> show chassis hardware | match FPC
FPC 0            REV 20   650-064383   VF1234567890      QFX5100-48S-6Q
  CPU            BUILTIN  BUILTIN                        FPC CPU
FPC 1            REV 08   650-064383   VF1234567891      QFX5100-48S-6Q
  CPU            BUILTIN  BUILTIN                        FPC CPU

Configure the VC

set virtual-chassis preprovisioned
set virtual-chassis no-split-detection
set virtual-chassis member 0 role routing-engine
set virtual-chassis member 0 serial-number VF1234567890
set virtual-chassis member 1 role routing-engine
set virtual-chassis member 1 serial-number VF1234567891

Use no-split-detection only in a VC with exactly two members.

Form the VC

Convert the ports that connect the two switches into VC ports:

request virtual-chassis vc-port set pic-slot 0 port 48
request virtual-chassis vc-port set pic-slot 0 port 49

The PIC slot and port numbers depend on your cabling; show chassis hardware shows them. Then watch the VC form with show virtual-chassis. FPC 0 and FPC 1 (Flexible PIC Concentrators) are the two switches, PIC 0 (Physical Interface Card) is the physical card, and the port is the port number.

Check that it is healthy

{master:0}
greg@SWITCH> show virtual-chassis

Preprovisioned Virtual Chassis
Virtual Chassis ID: 221a.4b12.128b
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    VF1234567890 qfx5100-48s-6q 129   Master*      N  VC   1  vcp-255/0/48
                                                                           1  vcp-255/0/49
1 (FPC 1)  Prsnt    VF1234567891 qfx5100-48s-6q 129   Backup       N  VC   0  vcp-255/0/48
                                                                           0  vcp-255/0/49

Both members are present (Prsnt) with their serial numbers. One holds the master role (Master*) and the other is the backup.

Management addresses and commit synchronisation

Once the VC is up, I give each member its own management address on em0 and add a shared address that always follows the master. You are not supposed to log in to a member directly, so the shared address is the one to use. I also enable commit synchronisation to keep both members in sync.

set system commit synchronize
set groups member0 when member member0
set groups member0 system host-name SW1
set groups member0 interfaces em0 unit 0 family inet address 192.168.1.1/24
set groups member0 interfaces em0 unit 0 family inet address 192.168.1.3/24 master-only
set groups member1 when member member1
set groups member1 system host-name SW2
set groups member1 interfaces em0 unit 0 family inet address 192.168.1.2/24
set groups member1 interfaces em0 unit 0 family inet address 192.168.1.3/24 master-only
set apply-groups member0
set apply-groups member1

192.168.1.1 is member 0, 192.168.1.2 is member 1, and 192.168.1.3 is always the current master. Always connect through that address, unless you know what you are doing.

Related

• Change the master role in a Juniper Virtual Chassis