Specifications

Extreme Networks Technical Brief
© 2010 Extreme Networks, Inc. All rights reser ved. SummitStack Stacking Technology—Page 7
Extreme Networks Technical Brief
Explanation of SummitStack Terms
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.
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
reacquired (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.
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.
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.
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 communi-
cate over the stack path.
Data Ports – This is the set of ports provided by a stack-
able 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.
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 congure
stacking easysetup command.
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 are possible without interrupting data
traffic or forcing any network reconvergence. This version
of SummitStack does not support hitless upgrade.
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.
Node – A node is a stackable switch that runs the
ExtremeXOS operating system. The terms node and
stackable switch are interchangeable.
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 – A node in the active topology plays a role in
the stack. There are three node roles: master (or primary),
backup, and standby.