SummitStack Terms

The following table describes the terms used for the SummitStack feature. These terms are listed in the recommended reading sequence.

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List of Stacking Terms

Term Description
Stackable switch A Summit family switch that provides two stacking ports and can participate in a stack.
Stacking port A physical interface of a stackable switch that is used to allow the connection of a stacking link. Stacking ports are point-to-point links that are dedicated for the purpose of forming a stack.
Native port A stacking port that can be used only for connections between stacked switches, not for data connections.
Alternate port A port that can be used for either stack connections or data connections.
Stacking link A cable that connects a stacking port of one stackable switch to a stacking port of another stackable switch, plus the stacking ports themselves.
Node A switch that runs the ExtremeXOS operating system and is part of a stack. Synonymous with stackable switch.
Stack SummitStack A set of stackable switches and their connected stacking links made with the intentions that: (1) all switches are reachable through their common connections; (2) a single stackable switch can manage the entire stack; and (3) configurable entities such as VLANs and link trunk groups can have members on multiple stackable switches. A stack consists of all connected nodes regardless of the state of the nodes.
Stack topology A contiguously connected set of nodes in a stack that are currently communicating with one another. All nodes that appear in the show stacking command display are present in the stack topology.
Stack path A data path that is formed over the stacking links for the purpose of determining the set of nodes that are present in the stack topology and their locations in the stack. Every node is always present in a stack path whether or not stacking is enabled on the node.
Control path A data path that is formed over the stacking links that is dedicated to carrying control traffic, such as commands to program hardware or software image data for software upgrade. A node must join the control path to fully operate in the stack. A node that is disabled for stacking does not join the control path, but does communicate over the stack path.
Active node

A node that has joined the control path. The active node can forward the control path messages or can process them. It can also forward data traffic. Only an active node can appear as a card inserted into a slot when the show slot {slot {detail} | detail } command is executed on the master node of the stack.

Active topology

A contiguous set of active nodes in a stack topology plus the set of stacking links that connect them. When an active topology consists of more than one node, each node in the active topology is directly and physically connected to at least one other node in the active topology. Thus, the active topology is a set of physically contiguous active nodes within a stack topology.

Candidate node A node that is a potential member of an active topology, or an active node that is already a member of an active topology. A candidate node may or may not be an active mode – that is, it may or may not have joined the control path.
Node role The role that each active node plays in the stack – either master (or primary), backup, or standby.
Master node The node that is elected as the master (or primary) node in the stack. The master node runs all of the configured control protocols such as OSPF, RIP, Spanning Tree, and EAPS.

The master node controls all of its own data ports as well as all data ports on the backup and standby nodes. To accomplish this, the master node issues specific programming commands over the control path to the backup and standby nodes.

Backup node The node assigned to take over the role of master if the master node fails. The master node keeps the backup node's databases synchronized with its own databases in preparation for such an event.

If and when the master node fails, the backup node becomes the master node and begins operating with the databases it has previously received. In this way, all other nodes in the stack can continue operating.

Standby node A node that is prepared to become a backup node in the event that the backup node becomes the master node. When a backup node becomes a master node, the new master node synchronizes all of its databases to the new backup node.

When a node operates in a standby role, most databases are not synchronized – except those few that directly relate to hardware programming.

Acquired node A standby or backup node that is acquired by a master node. This means that the master node has used its databases to program the hardware of the standby or backup node. The standby or backup node has acted as a hardware programming proxy, accepting the instructions of the master node to do so.

An acquired backup node maintains the databases needed to reflect why the hardware is programmed as it is. However, a standby node does not. An acquired node can be re-acquired (without a reboot) by the backup node only when the backup node becomes the master node, and only when both the backup and standby nodes were already acquired by the same master node at the time of its failure.

Data ports The set of ports on a stackable switch that are available for connection to your data networks. Such ports can be members of a user-configured VLAN or trunk group. They can be used for Layer 2 and 3 forwarding of user data traffic, for mirroring, or other features you can configure. Data ports are different from stacking ports.
Failover The process of changing the backup node to the master node when the original master node has failed.

When a master node fails, if a backup node is present, and if that node has completed its initial synchronization with the master node, then the backup node assumes the role of master node. The standby nodes continue their operation and their data ports do not fail.

Hitless failover A failover in which all data ports in the stack, except those of the failing master node, continue normal operation when the master node fails.
Hitless upgrade An operation in which the software image is upgraded, and the new image begins executing, without interrupting data traffic and without forcing any network reconvergence. This ExtremeXOS software version does not support hitless upgrade for a stack.
Node address The unique MAC address that is factory-assigned to each node.
Node role election The process that determines the role for each node. The election takes place during initial stack startup and elects one master node and one backup node. An election also takes place after a master node failover, when a new backup node is elected from the remaining standby nodes.
Node role election priority A priority assigned to each node, to bee used in node role election. The node with the highest node role election priority during a role election becomes the master node. The node with the second highest node role election priority becomes the backup.
Operational node A node that has achieved operational state as a card in a slot. The operational state can be displayed using the show slot {slot {detail} | detail }command.
System uptime The amount of time that has passed since the last node role election. You can display the system uptime by entering the show switch {detail } command on the master node.
Stack segment A collection of nodes that form a stack topology. The term is useful when a stack is severed. Each severed portion of the stack is referred to as a stack segment.
Stack state A state assigned by the stack to a node. You can display the stack state by entering the show stacking command.
Easy Setup A procedure that automatically configures the essential stacking parameters on every node for initial stack deployment, and then automatically reboots the stack to put the parameters into effect.

The choice to run Easy Setup is offered when you run the enable stacking {node-address node-address} command and the essential stacking parameters are unconfigured or inconsistent. It can also be invoked directly by running the configure stacking easy-setup command.