Stacking Introduction
©2008 Allied Telesis Inc. All rights reserved.
64.10
AlliedWare Plus
TM
Operating System Software Reference C613-50003-00 REV E
Software Version 5.2.1
VCS Fault Tolerance
Stack Member Failure and Recovery
Management IP Addresses
A single virtual MAC address, from the current Master, will be used as the stack MAC address.
If the stack master fails, the stack MAC address changes to reflect the new master's MAC
address.
Stack Resiliency Link
The purpose of the resiliency link is to provide the slave with status information that enables it
to detect whether the master is still operational after (the master) has suffered either a power-
down or software lock-up. This enables the other stack member to operate in the fall-back
mode, or to re-elect a new stack master. The
“State-change-table” on page 64.10
shows how
the stack members respond to various problems occurring on the master node.
Stack Recovery States
The following state-change-table shows stack member failure conditions and recovery actions
in situations where the resiliency link is present or absent.
State-change-table
1.
If the slave’s ports are still up, this may cause downstream switches with trunked ports to operate incorrectly
Event on Master Node
Reaction on Master
Reaction on Slave
Reaction on Slave
With Resiliency Link
Without Resiliency Link
Both stack links removed
No change
Fallback Action
Fallback Action
XEM-STK Removed / Faulty
No change
Fallback Action
Fallback Action
Software application problem
(lock-up or continual crashes)
Reboot as slave
Re-elect master
Re-elect master
software crash or lock-up
Frozen
Re-elect master
Fallback Action
Power-down or PSU failure
Powered Down
Re-elect master
Fallback Action
Event on Slave Node
Reaction on Master
Reaction on Slave
Reaction on Slave
Both stack links removed
No change
Fallback Action
Fallback Action
XEM-STK removed or faulty
No change
Fallback Action
Fallback Action
Software application failover (lock-
up or continual crashes)
No change
Re-boot as slave
Re-boot as slave
software crash or lock-up
No change
Frozen
1
Frozen
1
Power-down / PSU failure
No change
Powered Down
Powered Down