Understanding How The Port Aggregation Protocol Works - Cisco WS-C6506 Software Manual

Chapter 6 Configuring EtherChannel
•
•
•
•
•
•
•
•
•
•
•
With software release 6.3(1) and later releases, a PAgP-configured EtherChannel is preserved even if it
Note
contains only one port (this situation does not apply to LACP-configured EtherChannels). In software
releases prior to 6.3(1), traffic was disrupted when you removed a 1-port channel from spanning tree and
then added it to spanning tree as an individual port.
With software release 6.3(1) and later releases, due to the port ID handling by the spanning-tree feature,
Note
the maximum number of EtherChannels is 126 for a 6- or 9-slot chassis and 63 for a 13-slot chassis.

Understanding How the Port Aggregation Protocol Works

Note Use the information in these sections if you are configuring EtherChannel using PAgP. If you are using
LACP, see the
page
These sections describe PAgP:
•
•
•
OL-8978-04
An EtherChannel does not form with ports that have different GARP VLAN Registration Protocol
(GVRP), GARP Multicast Registration Protocol (GMRP), and QoS configurations.
An EtherChannel does not form with ports when you enable port security. You cannot enable port
security for ports in an EtherChannel.
An EtherChannel does not form if one of the ports is a SPAN destination port.
An EtherChannel does not form if protocol filtering is set differently on the ports.
Cisco Discovery Protocol (CDP) runs on the physical port even after the port is added to a channel.
VLAN Trunking Protocol (VTP) and Dual Ring Protocol (DRiP) run on the channel.
During fast switchover to the standby supervisor engine, all channeling ports are cleared on the
standby supervisor engine channeling configuration and state, and the links are pulled down
temporarily to cause partner ports to reset. All ports are reset to the nonchanneling state.
Ports with different dot1q port types cannot form a channel.
Ports with different jumbo frame configurations cannot form a channel.
Ports with different dynamic configurations cannot form a channel.
During high-availability switchover to the standby supervisor engine, all channeling ports remain
operational. Ports are reset only if there are events missing during the switchover.
"Understanding How the Link Aggregation Control Protocol Works" section on
6-13.
PAgP Modes, page 6-6
PAgP Administrative Groups, page 6-7
PAgP EtherChannel IDs, page 6-7
Understanding How the Port Aggregation Protocol Works
Catalyst 6500 Series Switch Software Configuration Guide—Release 8.7
6-5