Understanding the QFabric System Control Plane
The control plane in the QFabric system transports management traffic between QFabric system components to facilitate system operations, configuration, and maintenance. This topic covers:
Control Plane Elements
Control traffic within a QFabric system is carried across a redundant, scalable, out-of-band, Ethernet switching network called the control plane network. To maintain high availability, the QFabric system control plane is separated from the QFabric system data plane. Figure 1 shows a diagram of the QFabric system devices that compose the control plane network.
Figure 1: QFabric System Control Plane Network
The control plane consists of the following elements:
- Control plane switches—Provide
connectivity to the management interfaces of all QFabric system components
in the control plane network, including the Node devices, the Interconnect
devices, and the Director group. When you interconnect all QFabric
system devices to the control plane switches, the Director group can
manage the entire system. Depending on the size and scale of your
QFabric system, the control plane switches might be standalone switches
or might be groups of switches bundled into a Virtual Chassis (See
the Example topics in the Related Documentation section of this topic
to learn more about the control plane switch configuration required
for your QFabric system.)
For example, the control plane switch for the QFX3000-G QFabric system requires two Virtual Chassis containing four EX4200 switch members each. The two Virtual Chassis connect to each other across a 10-Gigabit Ethernet LAG link to provide maximum resiliency for the QFabric system control plane.
- Connections between the management interfaces
of the Node devices and the control plane switches—Enable
control plane connectivity from the Node devices to the rest of the
QFabric system. You must connect two management interfaces from each
Node device to the control plane switches. Connect each interface
to a different control plane switch to provide system resiliency.
For the most current guidance on the QFabric control plane configuration and cabling recommendations, see:
- Connections between the management interfaces
of the Interconnect devices and the control plane switches—Enable control plane connectivity from the Interconnect devices
to the rest of the QFabric system. You must connect the interfaces
in each Interconnect device to the control plane switches. Connect
each interface to a different control plane switch to provide system
resiliency.
For example, on QFX3008-I Interconnect devices, there are two Control Boards and two interfaces per Control Board, for a total of four connections per Interconnect device. To provide system resiliency, connect one interface from each Control Board to the first Virtual Chassis, and connect the second interface from each Control Board to the second Virtual Chassis.
For the most current guidance on the QFabric control plane configuration and cabling recommendations, see:
- Connections between the network module interfaces
of the Director group and the control plane switches—Enable control plane connectivity from the Director group
to the rest of the QFabric system. You must connect some interfaces
from the first network module in a Director device to one control
plane switch, and connect some interfaces from the second network
module in a Director device to the second control plane switch. Also,
you must connect the ports from the first network module to the primary
control plane switch for each Director device (which may vary depending
on the configuration of your Director group).
For the most current guidance on the QFabric control plane configuration and cabling recommendations, see:
- Routing Engines—Although they are automatically provisioned, specialized Routing Engines implement services such as default QFabric system infrastructure, device management, route sharing, and diagnostics to support the QFabric system. Routing Engines for control plane functions are virtual entities that run on the Director group.
- Fabric management protocol—A link-state protocol runs on the control plane network to identify and initialize QFabric system resources, support device redundancy, and support management communication throughout the QFabric system. The protocol is enabled by default.
Control Plane Services
The QFabric system control plane provides the infrastructure to support the following services for the QFabric system:
- System initialization
- Topology discovery
- Internal IP address and unique ID assignment
- Route information sharing
- Configuration delivery to Node devices
- Interdevice communication between Node devices, Interconnect devices, and the Director group
Many of these services are provided by the external Routing Engines that run in software on the Director group.
