6
In an IRF fabric, all chassis get and run the running configuration of the master. Any configuration
you have made is propagated to all members.
When you execute the
save
[
safely
] [
backup
|
main
] [
force
] command or the
save
file-url
all
command, the system saves the running configuration, as follows:
•
If the configuration auto-update function (the
slave auto-update config
command) is enabled,
saves the configuration as the startup configuration on all member switches for the next startup.
•
If the configuration auto-update function is disabled, saves the configuration as the startup
configuration on the master for the next startup.
By default, configuration auto-update is enabled.
For more information about configuration management, see
Fundamentals Configuration Guide
.
Master election
Master election is held each time the IRF fabric topology changes, for example, when the IRF fabric
is established, a new member device is plugged in, the master device fails or is removed, the IRF
fabric splits, or IRF fabrics merge.
Master election uses the following rules in descending order:
1.
Current master, even if a new member has higher priority.
When an IRF fabric is being formed, all member switches consider themselves as the master.
This rule is skipped.
2.
Member with higher priority.
3.
Member with the longest system uptime.
4.
Member with the lowest bridge MAC address.
The IRF fabric is formed on election of the master.
During an IRF merge, the switches of the IRF fabric that fails the master election must reboot to
rejoin the IRF fabric that wins the election.
After a master election, all subordinate switches reboot with the configuration on the master. Their
original configuration, even if it has been saved, does not take effect.
IRF multi-active detection
An IRF link failure causes an IRF fabric to split in two IRF fabrics operating with the same Layer 3
configurations, including the same IP address. To avoid IP address collision and network problems,
IRF uses multi-active detection (MAD) mechanisms to detect the presence of multiple identical IRF
fabrics, handle collisions, and recover from faults.
Multi-active handling procedure
The multi-active handling procedure includes detection, collision handling, and failure recovery.
Detection
The MAD implementation of the switch detects active IRF fabrics with the same Layer 3 global
configuration by extending the LACP, BFD, or gratuitous ARP protocol.
These MAD mechanisms identify each IRF fabric with a domain ID and an active ID (the member ID
of the master). If multiple active IDs are detected in a domain, MAD determines that an IRF collision
or split has occurred.
You can use at least one of these mechanisms in an IRF fabric, depending on your network topology.
For a comparison of these MAD mechanisms, see "
."
