CCNA: Etherchannels

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Description:

Remember these rules for matching on each end:
on-on
auto-desirable
active-passive

To create a basic layer 2 etherchannel:

Switch-1#conf t
Switch-1(config)#interface range fa0/1 – 3
Switch-1(config-if-range)#no shutdown
Switch-1(config-if-range)#channel-group 1 mode on # will display: Creating a port-channel interface Port-channel 1; uses pagp
Switch-1(config-if-range)#end
Switch-1#show etherchannel summary

# do the same thing for Switch-2

To configure how to load balance:

Switch(config)#port-channel load-balance [method]

Configuring Using PAGP:

Switch-1#conf t
Switch-1(config)#interface range fa0/1 – 3
Switch-1(config-if-range)#no shutdown
Switch-1(config-if-range)#channel-group 1 mode desirable
Switch-1(config-if-range)#channel-protocol pagp # this command is optional because pagp is default, but it should still be typed.
Switch-1(config-if-range)#end
Switch-1#show etherchannel summary
# change this to auto on the other switch

Configuring Using LACP:

Switch-1#conf t
Switch-1(config)#interface range fa0/1 – 3
Switch-1(config-if-range)#no shutdown
Switch-1(config-if-range)#channel-group 1 mode active
Switch-1(config-if-range)#channel-protocol lacp
Switch-1(config-if-range)#end
Switch-1#show etherchannel summary
# change this to passive on the other switch

Show Commands:

show etherchannel summary # Look for speed mismatches!
show interfaces port-channel 1 switchport
show EtherChannel 1 detail
show pagp neighbor
show lacp internal # port state, administrative key, LACP port priority, and the port number
show lacp neighbor # neighbour name, ID of the LACP neighbour, the neighbour device ID (MAC), and the neighbour port. The flags also indicate the mode the neighbour is operating in, as well as whether it is a physical learner, for example
show lacp sys-id # the system ID of the local switch. This is a combination of the switch MAC and LACP priority

 

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