6-13
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 6 Configuring EtherChannel
Understanding How the Link Aggregation Control Protocol Works
Understanding How the Link Aggregation Control Protocol
Works
Note
Use the information in these sections if you are configuring EtherChannel using LACP. If you are using
PAgP, see the
“Understanding How the Port Aggregation Protocol Works” section on page 6-5
.
This section contains the following descriptions:
•
LACP Modes, page 6-13
•
LACP Parameters, page 6-13
LACP Modes
You may manually turn on channeling by setting the port channel mode to
on
, and you may turn off
channeling by setting the port channel mode to
off
.
If you want LACP to handle channeling, use the
active
and
passive
channel modes. To start automatic
EtherChannel configuration with LACP, you need to configure at least one end of the link to
active
mode
to initiate channeling, because ports in
passive
mode passively respond to initiation and never initiate
the sending of LACP packets.
Table 6-2
describes the EtherChannel modes that are available in LACP.
LACP Parameters
The parameters that are used in configuring LACP are as follows:
•
System priority
You must assign a system priority that can be specified automatically or through the CLI (see the
“Specifying the System Priority” section on page 6-16
) to each switch running LACP. The system
priority is used with the switch MAC address to form the system ID and is also used during
negotiation with other systems.
•
Port priority
Table 6-2
EtherChannel Modes Available in LACP
Mode
Description
on
Mode that forces the port to channel without LACP. With the
on
mode, a usable
EtherChannel exists only when a port group in
on
mode is connected to another port group
in
on
mode.
off
Mode that prevents the port from channeling.
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 packet negotiation. (Default)
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.