Stack Membership; The Master Switch; Splitting And Merging One Stack - Lenovo RackSwitch G8264CS Application Manual

Stack Membership

The Master Switch

Splitting and Merging One Stack

254
G8264CS Application Guide for ENOS 8.4
A stack contains up to switches, interconnected by a stack LAG in a local ring
topology (see Figure 31 on page
failure is allowed.
An operational stack must contain one Master and one or more Members, as
follows:
Master

One switch controls the operation of the stack and is called the Master. The
Master provides a single point to manage the stack. A stack must have one and
only one Master. The firmware image, configuration information, and run‐time
data are maintained by the Master and pushed to each switch in the stack as
necessary.
Member

Member switches provide additional port capacity to the stack. Members
receive configuration changes, run‐time information, and software updates
from the Master.
 Backup
One member switch can be designated as a Backup to the Master. The Backup
takes over control of the stack if the Master fails. Configuration information and
run‐time data are synchronized with the Master.
An operational stack can have only one active Master at any given time. In a
normal stack configuration, one switch is configured as a Master and all others are
configured as Members.
When adding new switches to an existing stack, the administrator must explicitly
configure each new switch for its intended role as a Master (only when replacing a
previous Master) or as a Member. All stack configuration procedures in this
chapter depict proper role specification.
However, although uncommon, there are scenarios in which a stack may
temporarily have more than one Master switch. If this occurs, the switch with the
lowestMAC address will be chosen as the active Master for the entire stack. The
selection process is designed to promote stable, predictable stack operation and
minimize stack reboots and other disruptions.
If stack links or Member switches fail, any Member which cannot access either the
Master or Backup is considered isolated and will not process network traffic (see
"No Backup" on page 257). Members which have access to a Master or Backup (or
both), despite other link or Member failures, will continue to operate as part of
their active stack. A Member that is isolated due to link failure resets itself. After it
is up, if the link failure still exits, the Member stays in isolated state keeping all its
data links disabled. Only the management and stacking links are enabled. If the
Member was not configured when it went to isolated state, the Master pushes the
configuration when the Member joins back the stack.
260). With this topology, only a single stack link