Cisco Cisco IOS Software Release 12.2(27)SBC

Active—Places a port into an active negotiating state, in which the port initiates negotiations with 
remote ports by sending LACP packets. 

Passive—Places a port into a passive negotiating state, in which the port responds to LACP packets 
it receives but does not initiate LACP negotiation. In this mode, the port channel group attaches the 
interface to the bundle.

Both modes allow LACP to negotiate between ports to determine if they can form a port channel based 
on criteria such as port speed and trunking state. 

 describes the significant LACP parameters. 

When LACP is configured on ports, it tries to configure the maximum number of compatible ports in a 
port channel, up to the maximum allowed by the hardware (four ports). If LACP cannot aggregate all the 
ports that are compatible (for example, the remote system might have more restrictive hardware 
limitations), then all the ports that cannot be actively included in the channel are put in hot standby state 
and are used only if one of the channeled ports fails. 

In prior Cisco IOS releases, the Cisco-proprietary Port Aggregation Control Protocol (PAgP) was used 
to configure port channels. LACP and PAgP do not interoperate with each other. Ports configured to use 
PAgP cannot form port channels on ports configured to use LACP. Ports configured to use LACP cannot 
form port channels on ports configured to use PAgP.

LACP system priority

A LACP system priority is configured on each router running LACP. The 
system priority can be configured automatically or through the CLI. LACP 
uses the system priority with the router MAC address to form the system 
ID and also during negotiation with other systems. 

The LACP system ID is the combination of the LACP system priority 
value and the MAC address of the router. 

LACP port priority

A LACP port priority is configured on each port using LACP. The port 
priority can be configured automatically or through the CLI. LACP uses 
the port priority with the port number to form the port identifier. The port 
priority determines which ports should be put in standby mode when there 
is a hardware limitation that prevents all compatible ports from 
aggregating. 

LACP administrative key LACP automatically configures an administrative key value equal to the 

channel group identification number on each port configured to use LACP. 
The administrative key defines the ability of a port to aggregate with other 
ports. A port’s ability to aggregate with other ports is determined by these 
factors: 

Port physical characteristics, such as data rate, duplex capability, and 
point-to-point or shared medium 

Configuration restrictions that you establish 

LACP maximum number 
of bundled ports

You can restrict the maximum number of bundled ports allowed in the port 
channel using the lacp max-bundle command in interface configuration 
mode.