6-3
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
OL-8978-04
Chapter 6 Configuring EtherChannel
Port Aggregation Control Protocol and Link Aggregation Control Protocol
Port Aggregation Control Protocol and Link Aggregation Control
Protocol
Port Aggregation Control Protocol (PAgP) and Link Aggregation Control Protocol (LACP) are two
different protocols that allow ports with similar characteristics to form a channel through dynamic
negotiation with adjoining switches. PAgP is a Cisco-proprietary protocol that can be run only on Cisco
switches and those switches that are released by licensed vendors. LACP, which is defined in
IEEE 802.3ad, allows Cisco switches to manage Ethernet channeling with devices that conform to the
802.3ad specification.
Note MAC address notification settings are ignored on PAgP and LACP EtherChannel ports.
To use PAgP, see the “Understanding How the Port Aggregation Protocol Works” section on page 6-5.
To use LACP, see the “Understanding How the Link Aggregation Control Protocol Works” section on
page 6-13.
EtherChannel Configuration Guidelines
If improperly configured, some EtherChannel ports are disabled automatically to avoid network loops
and other problems.
Note Except where specifically differentiated, these guidelines apply to both PAgP and LACP.
These sections provide the guidelines for EtherChannel configuration:
• Port Configuration Guidelines, page 6-3
• VLAN and Trunk Configuration Guidelines, page 6-4
• Interaction with Other Features Guidelines, page 6-4
Port Configuration Guidelines
This section describes the guidelines for port configuration:
• You can have a maximum of eight compatibly configured ports per EtherChannel; the ports do not
have to be contiguous or on the same module.
• All ports in an EtherChannel must be placed in the same administrative group. Enter the show
channel group command to verify the administrative group, and enter the set port channel
mod/ports admin_group command if necessary to assign ports to the same administrative group.
• All ports in an EtherChannel must use the same protocol; you cannot run two protocols on one
module.
• PAgP and LACP are not compatible; both ends of a channel must use the same protocol.
Note You can configure the switch manually with PAgP on one side and LACP on the other side
in the on mode.
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