Notebook – EtherChannel

Etherchannel - Aggregation of redundant links
Etherchannel takes bundles of redundant links (up to 8 links) and pools the bandwidth into one logical link and load balances all
 traffic across those physical links.
Etherchannel has automatic failover as well.

Port Aggregation Protocol (PAGP) -
Cisco's proprietary etherchannel negotiation protocol.
Port modes: 
.Auto - Will only negotiate an etherchannel with the switch on the other end of the link if other end negotiates it.
.Desirable - Will actively attempt to negotiate an etherchannel port with the other end of the link, 
usually to break the ice in the auto state on the switch on the other end of the link.
.On - Hard coding a port to negotiate an etherchannel.

Link Aggregation Control Protocol (LACP)
Industry standard, declared 802.3AD by IEEE
Port modes: 
.Passive - same as auto 
.Active - same as desirable
.On - same as cisco "on"
Layer 2 Etherchannel 
Acts as a normal layer 2 switched bundle of links.
Layer 3 Ether Channel
Turns the Layer 2 Etherchannel into a Port Channel that has routing capabilities.
Same config needs to take place on both ends of the link. In order for the etherchannel to be up they other side needs to be configured.
 No configuration on the other with active or passive config the ports will just return to normal switching port.
Switch(config)#interface range fast 0/23 - 24 - select the ports to create the etherchannel
Switch(config-if-range)#channel-protocol <LACP> <PAGP> - select the protocol
Switch(config-if-range)#channel-group <1-64> - assign the etherchannels a group number 
Switch(config-if-range)#channel-group <1-64> <mode [passive/auto][active/desirable][on]>
Will create a new interface called Port-Channel <1-64>. Configuration for L2 etherchannel.

Layer 3 Etherchannel:
(assume port-channel 1 was created out of fast 0/23 and 0/24)
Turn channel group 1 off first:
Switch(config)#interface range fast 0/23 - 24 - selected ports
Switch(config-if-range)#no channel-group 1
Switch(config-if-range)#exit - leave interface range configuration
Switch(config)#interface port-channel 1
Switch(config-if)#no switchport - to remove switching capabilities from this port, and gain routed capabilities
Switch(config-if)#ip address - add an ip address to the port channel
Switch(config-if)#interface range fast 0/23 - 24
Switch(config-if-range)#channel-group 1 mode desirable - to create the channel group and place into desirable negotiation mode.

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