Juniper QFX3500, Hardware Documentation

Page: 31 / 669

The default primary-role priority value for all devices is 128. You should always configure two spine devices
with the highest primary-role priority to ensure the Routing Engine role is assigned to a spine device.
In a nonprovisioned VCF, you must manually configure every VCP.
Configuration File Management in a VCF
You configure a VCF by logging onto the primary Routing Engine and making configuration changes. See
the next section for information on logging into a VCF.
The configuration file that is modified when you are on the primary Routing Engine is automatically shared
with all other devices in the VCF when it is committed. Each device stores it’s own copy of the configuration
file.
Logging into a Virtual Chassis Fabric
The recommended method of logging into a VCF is through the use of a Virtual Management Ethernet
(VME) interface. The VME interface is a logical interface representing all of the out-of-band management
ports on the member devices. When you connect to the VCF configuration using the VME interface’s IP
address, the connection is always redirected to the management port on device in the primary Routing
Engine role. The VME interface is not tied to a device, so it can always be used to log in to the VCF even
after the primary Routing Engine changes. We recommend cabling the management ports—an me or em
interface—on each Routing Engine in your VCF to support the VME interface.
If you log in to the console port of any member device in a VCF, your session is automatically redirected
to the device acting in the primary Routing Engine role.
Understanding Interface Numbering
Interfaces in Junos OS are specified as follows:
type-fpc/pic/port
A VCF applies this convention as follows:
•
type—The interface type.
•
fpc—Flexible PIC Concentrator. In a VCF, the fpc is the member ID of the switch. For instance, the fpc
of member 16 in the VCF is 16.
•
pic—the number of the PIC (Physical Interface Card) on the member device.
•
port—the port number.
For more detailed information on interface numbering, see Understanding Interface Naming Conventions.
7