Godbus

1. EtherChannel Overview
An EtherChannel bundles individual Ethernet links into a single logical link that provides the aggregate bandwidth of up to eight physical links.
A Catalyst 6500 series switch supports a maximum of 64 EtherChannels (256 with Release 12.1(2)E andearlier). You can form an EtherChannel with up to eight compatibly configured LAN ports on any module in a Catalyst 6500 series switch. All LAN ports in each EtherChannel must be the same speedand must all be configured as either Layer 2 or Layer 3 LAN ports.
PAgP = Port Aggregation Control Protocol, a Cisco-proprietary protocol.
LACP = Link Aggregation Control Protocol, is defined in IEEE 802.3ad.
PAgP and LACP do not interoperate with each other. Ports configured to use PAgP cannot form EtherChannels with ports configured to use LACP. Ports configured to use LACP cannot form EtherChannels with ports configured to use PAgP.

2. PAgP EtherChannel
PAgP packets are exchanged only between ports in auto and desirable modes.
Both the auto and desirable modes allow PAgP to negotiate between LAN ports to determine if they can form an EtherChannel, based on criteria such as port speed and trunking state. Layer 2 EtherChannels also use VLAN numbers.
LAN ports can form an EtherChannel when they are in different PAgP modes if the modes are compatible. A LAN port in desirable mode can form an EtherChannel successfully with another LAN port that is in desirable or auto mode. But a LAN port in auto mode cannot form an EtherChannel with another LAN port that is also in auto mode, because neither port will initiate negotiation.

3. LACP EtherChannel
Release 12.1(13)E and later releases support IEEE 802.3ad LACP EtherChannels. LACP packets are exchanged only between ports in passive and active modes.
Once LACP identifies correctly matched Ethernet links, it facilitates grouping the links into an EtherChannel. The EtherChannel is then added to the spanning tree as a single bridge port.
LACP system priority—You must configure an LACP system priority on each switch running LACP. The system priority can be configured automatically or through the CLI. LACP uses the system priority with the switch MAC address to form the system ID and also during negotiation with other systems.
LACP port priority—You must configure an LACP port priority on each port configured to use 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. LACP uses the port priority to decide 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.

4. Configuration EtherChannel
A. Layer 3 EtherChannel:
Router(config)# interface port-channel 1
Router(config-if)# ip address 172.32.52.10 255.255.255.0
B. Configuration EtherChannel:
Router(config-if)# channel-group number mode {active | auto | desirable | on | passive}
Router(config-if)# channel-protocol {lacp | pagp}
Router(config-if)# lacp port-priority priority_value
Router(config)# lacp system-priority priority_value
Router(config)# port-channel load-balance {src-mac | dst-mac | src-dst-mac | src-ip | dst-ip | src-dst-ip | src-port | dst-port | src-dst-port}
C. Show Commands:
Router# show running-config interface port-channel number
Router# show interfaces type slot/port etherchannel
Router# show lacp sys-id
Router# show etherchannel load-balance