In EtherChannel,
you can combine multiple physical links between switches into a single
logical link to increase the bandwidth size. You can combine maximum
eight physical links into one etherchannel link for the purpose of high
speed communication and load balancing between switches.
Etherchannel can be configured using one of these modes.
Link Aggregation Control Protocol (LACP) and Port Aggregation Protocol (PAgP)
We
will configure here only LACP in detail and the remaining protocol will
be discussed in the next tips.
Link Aggregation Control Protocol is non-proprietary
protocol and is part of an IEEE specification (802.3ad). You can use
following combination to create etherchannel using
LACP.
Active on Switch-1
- Active on Switch-2
Active on Switch-1
- Passive on Switch-2
Passive on Switch-1
- Active on Switch-2
Follow the topology of two switches networks in the given figure for
etherchannel:
Configuration on Switch-A
First run the Show interface trunk command to verify the trunk
links.
Switch-A# Show interface trunk
Port Mode
Encapsulation Status Native
vlan
Fa0/1
desirable n-isl
trunking 1
Fa0/2
desirable n-isl
trunking 1
Fa0/3
desirable n-isl
trunking 1
Port Vlans allowed on trunk
Fa0/1
1-4094
Fa0/2
1-4094
Fa0/3
1-4094
Port Vlans allowed and active in
management domain
Fa0/1
1
Fa0/2
1
Fa0/3
1
Port Vlans in spanning tree forwarding
state and not pruned
Fa0/1
1
Fa0/2
1
Fa0/3
1
Ports
fastethernet 0/1 - 3 to be configured in the etherchannel:
Switch-A(config)#interface range fastEthernet 0/1 -3
Switch-A(config-if-range)#
channel-protocol lacp
Configure
the
lacp protocol to be used in this channel
Switch-A(config-if-range)# channel-group 1 mode active
Configure the mode active to be used in lacp
Configuration on Switch-A
Ports
fastethernet 0/1 - 3 to be configured in the etherchannel:
Switch-B(config)#interface range fastEthernet 0/1 -3
Switch-B(config-if-range)#
channel-protocol lacp
Configure the
lacp
protocol to be used in this channel
Switch-B(config-if-range)# channel-group 1 mode active
Configure the mode active to be used in lacp
Now
run show command to display the etherchannel configurations on Switch-B
and Switch-A.
Switch-B#show
etherchannel 1 summary
Flags: D - down P - in
port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
u - unsuitable for bundling
U - in use f - failed to allocate
aggregator
d - default port
Number of channel-groups in use: 1
Number of aggregators:
1
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------
1
Po1(SU) LACP
Fa0/1(P) Fa0/2(P) Fa0/3(P
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