Stacking Terminology

Stack Unit Roles

• Active controller: Handles stack management and configures all system- and interface-level features.
• Standby controller: The stack member with the highest priority after the active controller. The standby controller takes over if the current active controller fails.
• Stack member: A unit functioning in the stack in a capacity other than active controller or standby controller.
• Stack unit: Any device functioning within the stack, including the active controller and standby controller.
• Standalone unit: An eligible unit that is not part of a stack that can be interchanged with an active controller without reload. A standalone unit becomes an active controller when any member joins the stack. An active controller becomes a standalone when it loses all stack members.

Stacking Terms

• Bootup role: The role a unit takes during the boot sequence. This role can be standalone, active controller, standby controller, stack member, or PE (port extender, in an 802.1br Campus Fabric network).

• Clean unit: A unit that contains no startup flash configuration or runtime configuration. To erase old configuration information, enter the erase startup-config command and reset the unit without entering the write memory command. If a stack member is without an active controller, you can access its local console and enter the stack unconfigure clean command to convert it to a clean unit. Converting a unit to a clean unit does not remove its loaded licenses.
  Note: An ICX 7650 device with startup-config flash using 40-Gbps stacking ports that has no other configuration is treated as a clean unit. Because an ICX 7650 device that uses 40-Gbps stacking requires the rear-module stack-40g command followed by the write memory and reload commands to change the default 100-Gbps stacking ports to 40-Gbps stacking ports, the related startup-config flash must be present.
• Control path: A path across stacking links dedicated to carrying control traffic such as commands to program hardware or software image data for upgrades. A stack unit must join the control path to operate fully in the stack.
• Default ports: FastIron devices used the default-ports to define stacking port candidates. The stack default-ports command is deprecated in Release 08.0.90. However, the default-ports are still used internally to define which ports can be stacking ports. From Release 08.0.90, these ports are often referred to as valid-stack-ports or simply as stack-ports. See also the term Valid-stack-port set.
• Direction: Every stack unit has one or two directions for linking to other units. Each direction is either a stack-port or stack-trunk. System output, for example, in show commands, uses "D0" or "dir 0" to indicate the first direction.
• Dynamic configuration: A unit configuration that is dynamically learned by a new stack unit from the active controller. A dynamic configuration disappears when the unit leaves the stack. The configuration becomes a static configuration after you enter the write memory command.
• Interprocessor Communications (IPC): The process by which proprietary packets are exchanged between stack unit CPUs.
• IronStack: A set of RUCKUS stackable units (maximum of twelve) and their connected stacking links so that all units can be accessed through their common connections. A single unit can manage the entire stack, and configurable entities, such as VLANs and trunk groups, can have members on multiple stack units.
• Linear-topology trunk: A type of trunk available only in a two-unit stack to place stack-ports in both directions into a single trunk. The resulting trunk achieves the same redundancy as a two-unit ring and doubles the bandwidth of the stacking ports. All ports in the linear-topology trunk are used in forwarding between the two units, in contrast to a two-unit ring, which uses only one direction, even when two paths are available. This feature is available in FastIron release 08.0.90 and later. Refer to Support for two-unit stack linear trunks.
• Non-Functioning stack unit: A stack unit that is recognized as a stack member, and is communicating with the active controller over the Control Path, but is in a non-functioning state. A non-functioning stack unit will drop or discard traffic from non-stacked ports. This may be caused by an image or configuration mismatch.
• Reserved / provisional unit: A unit configuration number that has no physical unit associated with it.
• Sequential connection: Stack unit IDs, beginning with the active controller, are sequential. For example, 1, 3, 4, 6, 7 is sequential if active controller is 1. 1, 7, 6, 4, 3 are non-sequential in a linear topology, but become sequential in a ring topology when counted from the other direction as: 1, 3, 4, 6, 7. Gaps in numbering are allowed.
• Stack interactive-setup: An interactive tool that assists in discovering units and constructing a stacking system. The stack interactive-setup utility can also discover new links between existing stack units, enlarge a stacking trunk, or change a chain topology to a ring. The utility also provides an option for users to change member IDs interactively.
  Note: RUCKUS recommends the use of stack interactive-setup in preference to stack zero-touch provisioning (stack zero-touch-enable configuration) because the interactive-setup utility allows you more flexibility when selecting units, assigning, IDs, or configuring a linear-topology trunk. Stack interactive-setup displays warning messages about connection errors, making them easier to spot.
• Stack path: A data path formed across the stacking links to determine the set of stack members that are present in the stack topology, and their locations in the stack.
• Stack slot: A slot in a stack is synonymous with a line model in a chassis.
• Stack topology: A contiguously-connected set of stack units in an ICX stack that are currently communicating with each other. All units that are present in the stack topology appear in output from the show stack command.
• Stacking link: A cable that connects a stacking port on one unit to a stacking port on another unit.
• Stacking port: A physical interface on a stack unit that connects a stacking link. Stacking ports are point-to-point links that exchange proprietary packets. Stacking ports cannot be configured for any other purpose while operating as stacking ports. The number of available stacking ports depends on the platform. Some ports can be configured as either stacking ports or regular data ports. Refer to the hardware installation guide for the specific device for more information.
  • Stack-port: A configuration command used to define a single stacking port in one direction.
  • Stack-trunk: A configuration command used to define multiple stacking ports in one direction. A trunk is also referred to as a link aggregation group (LAG).
• Stack zero-touch provisioning (ZTP): Automatic discovery of stack members when stack zero-touch-enable is configured. When stack zero-touch provisioning is enabled, the system performs stack interactive-setup every three minutes in background, without any prompts to the user or opportunities for user input. The resulting configuration is similar to running stack interactive-setup and accepting all suggested values.
• Standalone unit: A unit that is not enabled for stacking, or an active controller without any standby controller or stack members.
• Static configuration: A configuration that remains in the database of the active controller even if the unit it refers to is removed from the stack. Static configurations are derived from the startup configuration file during the boot sequence, are manually entered, or are converted from dynamic configurations after a write memory command is issued.
• Trunked stacking port (trunk): A trunk consists of multiple stacking ports and is treated as one logical link. It provides more bandwidth and better resilience than individually connected ports. A trunk is often referred to as a link aggregation group (LAG).
• Unit replacement: The process of swapping out a unit with a clean unit that contains the same modules. Unit replacement is periodically triggered in background and does not require any command entry.
• Valid-stack-port set: A set of stacking ports that must be used to configure stacking. There are two stacking directions, so each valid-stack-port set contains two ports. Each stack direction must start with a specific port in the valid-stack-port set. For example, an ICX 7150-24P device has the valid-stack-port set (x/3/1, x/3/3, 2). In this notation, the "2" indicates that a stack-trunk can have up to two ports. The stack-port configuration must be a valid-stack-port (for an ICX 7150-24P, x/3/1 or x/3/3). A stack-trunk configuration contains contiguous ports starting from a valid-stack-port, for example, for an ICX 7150-28P device, stack-trunk 1/3/3 to 1/3/4. A platform may support multiple valid-stack-port sets. Both stacking directions must originate from the same set. For example, an ICX 7250 device has two valid-stack-port sets, (x/2/1, x/2/3, 2) and (x/2/5, x/2/7, 2). When you configure an ICX 7250 for stacking, you cannot configure stack-port 1/2/1 and stack-port 1/2/5 in the same unit. For more information, refer to Valid-stack-port sets and to the stacking overview section for a particular ICX device.