Knowledge Base

Design & Configure

LACP mode configuration (Cisco)

Technology: Switching
Area: Link aggregation
Vendor: Cisco
Software: 12.X , 15.X
Platform: Catalyst platforms

Link Aggregation Control Protocol IEEE 802.3ad (LACP) is an open standard of Ethernet link aggregation. LACP allows Cisco switches to manage Ethernet channels between switches that conform the 802.3ad protocol. You can configure maximum 16 ports to form a channel depending on IOS version and platform. Eight of the ports are in active mode and the other eight are in hot-standby mode. There are few LACP modes: “active”, “passive” and “on”.

First, to configure logical etherchannel interface:

Switch#configure terminal
Switch(config)#interface port-channel 5
Then you need to assign the physical ports and specify LACP mode. 

LACP mode Active:

LACP mode that places a port into an active negotiating state, in which the port initiates negotiations with other ports by sending LACP packets.

To configure port as an LACP active mode:

switch# configure terminal
switch(config)# interface fastethernet 0/1
switch(config-if)# channel-group 5 mode active

To verify if ports are bundled:

Switch#show ethernet channel summary

 

LACP mode Passive:

LACP mode that places a port into a passive negotiating state, in which the port responds to LACP packets that it receives but does not initiate LACP negotiation.

 

To configure port as an LACP active mode:

switch# configure terminal
switch(config)# interface fastethernet 0/1
switch(config-if)# channel-group 5 mode paasive

To verify if ports are bundled:

Switch#show ethernet channel summary

 

LACP mode On:

All static EtherChannels, that is, the port is not running LACP messaging but static bundling. With this mode the switch or the other end switch will not recognize any problem with ether channel and will not tell about problem.

switch# configure terminal
switch(config)# interface fastethernet 0/1
switch(config-if)# channel-group 5 mode on

To verify if ports are bundled:

Switch#show ethernet channel summary

 

Check how to configure PAgP on Cisco switch.

Author: Marcin Bialy
 
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