Cisco Catalyst 2960 Series, Configuration Manual

Page: 431 / 2288

Purpose Command or Action
Returns to privileged EXEC mode. end
Example:
Switch(config-if)#
end
Step 5
Related Topics
PAgP Learn Method and Priority, on page 330
EtherChannel Configuration Guidelines, on page 338
Default EtherChannel Configuration, on page 337
Monitoring EtherChannel, PAgP, and LACP Status, on page 358
Layer 2 EtherChannel Configuration Guidelines, on page 340
Configuring LACP Hot-Standby Ports
When enabled, LACP tries to configure the maximum number of LACP-compatible ports in a channel, up to
a maximum of 16 ports. Only eight LACP links can be active at one time. The software places any additional
links in a hot-standby mode. If one of the active links becomes inactive, a link that is in the hot-standby mode
becomes active in its place.
If you configure more than eight links for an EtherChannel group, the software automatically decides which
of the hot-standby ports to make active based on the LACP priority. To every link between systems that
operate LACP, the software assigns a unique priority made up of these elements (in priority order):
• LACP system priority
• System ID (the switch MAC address)
• LACP port priority
• Port number
In priority comparisons, numerically lower values have higher priority. The priority decides which ports
should be put in standby mode when there is a hardware limitation that prevents all compatible ports from
aggregating.
Determining which ports are active and which are hot standby is a two-step procedure. First the system with
a numerically lower system priority and system ID is placed in charge of the decision. Next, that system
decides which ports are active and which are hot standby, based on its values for port priority and port number.
The port priority and port number values for the other system are not used.
You can change the default values of the LACP system priority and the LACP port priority to affect how the
software selects active and standby links.
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
349
How to Configure EtherChannels