SummitStack Terms

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

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 native port is a stacking port that can only be used for connections between stacked switches.
Alternate Port	An alternate port is a port that can be used for either stack connections or data connections.
Stacking Link	A wire that connects a stacking port of one stackable switch to a stacking port of another stackable switch, plus the stacking ports themselves.
Node	A node is a stackable switch that runs the ExtremeXOS operating system. The terms node and stackable switch are used interchangeably in this chapter.
Stack	A stack is 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 these 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 the control path messages. 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 form the active topology. 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. NOTE: A node in the stack topology may not necessarily be a member of the active topology.
Candidate Node	A node that is a potential member of an active topology is called a candidate node. An active node is also a candidate node. Unlike an active node, a candidate node may not have joined the control path.
Node Role	A node in the active topology plays a role in the stack. There are three node roles: master (or primary), backup, and standby.
Master Node Role	A node that is elected as the master (or primary) runs all of the configured control protocols such as OSPF, RIP, Spanning Tree, EAPS, and so forth. The master node controls all data ports on itself, the backup node, and all standby nodes. The master node issues specific programming commands over the control path to the backup or standby nodes to accomplish this purpose.
Backup Node Role	The node that is operating in the backup node role takes over the master node role if the master node fails. The master node keeps the backup node databases in synchronization with its own database in preparation for this event. Upon transfer of role, the backup node becomes the master node and begins operating with the databases it has previously received. This allows all other nodes in the stack to continue operating even after the master node fails.
Standby Node Role	A node that is executing the standby node role is prepared to become a backup node in the event that the backup node becomes the master node. When becoming a backup node, the new master node synchronizes all of its databases to the new backup node. As a standby node, most databases are not synchronized, except for those few that directly relate to hardware programming.
Acquired Node	A standby or backup node is normally acquired by a master node. This means 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 standby node does not maintain the databases needed to reflect why the hardware is programmed as it is; however, a backup node does. An acquired node can only be re-acquired (without a reboot) by the backup node when that backup node becomes a master node, and only if both the backup and standby nodes were already acquired by the same master node at the time of its failure.
Data Ports	This is the set of ports provided by a stackable switch that are available to you for connection to your data networks. Such ports can be members of a user configured VLAN or trunk group, and can be used for Layer 2 and 3 forwarding of user data traffic or for mirroring, or other features you can configure. This term does not refer to stacking ports.
Failover	When a node that is executing the master node role in a stack fails, a failover is initiated. If there is a node that is executing the backup node role, and if the node has completed its initial synchronization with the master node before it failed, the backup node takes on the master node role. The standby nodes continue their operation, and their data ports do not fail.
Hitless Failover	A failover whereby all data ports in the stack, except those of the failing master node, continue normal operation when the master node fails.
Hitless Upgrade	This is an operation where an upgrade of the software image and the commencement of the new image execution is possible without interrupting data traffic or forcing any network reconvergence. This ExtremeXOS software version does not support hitless upgrade for a stack.
Node Address	Stacking nodes are uniquely identified by their node address. This is actually the MAC address that was factory assigned to each node.
Node Role Election	This is the process that determines the role for each node. The election takes place during initial stack startup and elects a master and a 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	For each node, the stack computes a priority to be 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	This is 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	This is the amount of time that has passed since a stack first elected a master node after the stack last rebooted. The time can be displayed on a master node by entering the show switch {detail } command.
Stack Segment	This is 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. This can be displayed using the command show stacking.
Easy-Setup	Easy-setup is a procedure that configures the essential stack parameters of every node for initial stack deployment, and automatically reboots the stack to put the parameters into effect. The choice to run easy-setup is offered when the enable stacking {node-address node-address} command is run and the essential stacking parameters are unconfigured or inconsistent. It can also be invoked directly by running the configure stacking easy-setup command.

Published March 2020prev | next

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