EtherChannel is a technology used to aggregate multiple physical Ethernet links into a single logical link, providing higher bandwidth and redundancy.
Link Aggregation Control Protocol (LACP) is an open standard protocol used for negotiating and managing EtherChannels.
In this blog post, we’ll demonstrate how to configure LACP EtherChannel on Cisco switches. Also, we will implement load balancing on Cisco switches and run through some etherchannel show commands.
Network Topology
The network topology we will be making use of in this post is shown below. As you can see, it consists of two switches joined together using two straight-through cables.
In this demonstration, we will configure LACP on each of the switches so that the two links can be aggregated into one link with a higher bandwidth.
Link Aggregation Control Protocol(LACP) configuration
Here are steps to configure LACP on the two Switches shown in the network topology above;
Step 1: Configure LACP EtherChannel on SW1
SW1(config)#interface range ethernet0/0-1
SW1(config-if-range)#channel-group 1 mode activeThis command creates a port-channel interface and activates LACP negotiation on SW1. This portchannel turns both ethernet0/0 and ethernet0/1 into a portchannel.
Step 2: Configure LACP EtherChannel on SW2
SW2(config)#interface range ethernet0/0-1
SW2(config-if-range)#channel-group 1 mode passiveThis command creates a port-channel interface and configures SW2 to passively negotiate with SW1 using LACP.
Step 3: Verify Etherchannel Configuration
>Verify Port-channel1 on SW1
SW1#show ip interface brief
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 unassigned YES unset up up
Ethernet0/1 unassigned YES unset up up
Ethernet0/2 unassigned YES unset up up
Ethernet0/3 unassigned YES unset up up
Port-channel1 unassigned YES unset up up
The output confirms the creation of Port-channel1 on SW1.
>Verify Port-channel1 on SW2
SW2#show ip interface brief
Interface IP-Address OK? Method Status Protocol
Ethernet0/0 unassigned YES unset up up
Ethernet0/1 unassigned YES unset up up
Ethernet0/2 unassigned YES unset up up
Ethernet0/3 unassigned YES unset up up
Port-channel1 unassigned YES unset up up The output confirms the creation of Port-channel1 on SW2.
LACP Show Commands
Here are some LACP Show commands and their output on our network;
1. show etherchannel summary
This command provides a summary of the EtherChannel configuration on SW1.
Switch1
SW1#show etherchannel summary
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use f - failed to allocate aggregator
M - not in use, minimum links not met
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SU) LACP Et0/0(P) Et0/1(P) <--Switch2
SW2#show etherchannel summary
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use f - failed to allocate aggregator
M - not in use, minimum links not met
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SU) LACP Et0/0(P) Et0/1(P) <-- 2. show etherchannel <number> port-channel
This command displays detailed information about Port-channel on a switch.
Switch1
SW1#show etherchannel 1 port-channel
Port-channels in the group:
---------------------------
Port-channel: Po1 (Primary Aggregator)
------------
Age of the Port-channel = 0d:00h:07m:15s
Logical slot/port = 16/0 Number of ports = 2
HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = LACP
Port security = Disabled
Ports in the Port-channel:
Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Et0/0 Active 0
0 00 Et0/1 Active 0
Time since last port bundled: 0d:00h:00m:14s Et0/1
Time since last port Un-bundled: 0d:00h:00m:20s Et0/0Switch2
SW2#show etherchannel 1 port-channel
Port-channels in the group:
---------------------------
Port-channel: Po1 (Primary Aggregator)
------------
Age of the Port-channel = 0d:00h:05m:53s
Logical slot/port = 16/0 Number of ports = 2
HotStandBy port = null
Port state = Port-channel Ag-Inuse
Protocol = LACP
Port security = Disabled
Ports in the Port-channel:
Index Load Port EC state No of bits
------+------+------+------------------+-----------
0 00 Et0/0 Passive 0
0 00 Et0/1 Passive 0
Time since last port bundled: 0d:00h:00m:44s Et0/1
Time since last port Un-bundled: 0d:00h:00m:49s Et0/03. show interfaces <interface_name> etherchannel
These commands display detailed information about EtherChannel configuration on each interface of a switch.
Switch 1
SW1#show interfaces ethernet0/0 etherchannel
Port state = Up Mstr Assoc In-Bndl
Channel group = 1 Mode = Active Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = LACP
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Et0/0 SA bndl 32768 0x1 0x1 0x1 0x3D
Partner's information:
LACP port Admin Oper Port Port
Port Flags Priority Dev ID Age key Key Number State
Et0/0 SP 32768 aabb.cc00.2a00 3s 0x0 0x1 0x1 0x3C
Age of the port in the current state: 0d:00h:01m:50s
SW1#show interfaces ethernet0/1 etherchannel
Port state = Up Mstr Assoc In-Bndl
Channel group = 1 Mode = Active Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = LACP
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Et0/1 SA bndl 32768 0x1 0x1 0x2 0x3D
Partner's information:
LACP port Admin Oper Port Port
Port Flags Priority Dev ID Age key Key Number State
Et0/1 SP 32768 aabb.cc00.2a00 19s 0x0 0x1 0x2 0x3C
Age of the port in the current state: 0d:00h:02m:28sSwitch 2
SW2#show interfaces ethernet0/0 etherchannel
Port state = Up Mstr Assoc In-Bndl
Channel group = 1 Mode = Passive Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = LACP
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Et0/0 SP bndl 32768 0x1 0x1 0x1 0x3C
Partner's information:
LACP port Admin Oper Port Port
Port Flags Priority Dev ID Age key Key Number State
Et0/0 SA 32768 aabb.cc00.1a00 9s 0x0 0x1 0x1 0x3D
Age of the port in the current state: 0d:00h:03m:47s
SW2#show interfaces ethernet0/1 etherchannel
Port state = Up Mstr Assoc In-Bndl
Channel group = 1 Mode = Passive Gcchange = -
Port-channel = Po1 GC = - Pseudo port-channel = Po1
Port index = 0 Load = 0x00 Protocol = LACP
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Et0/1 SP bndl 32768 0x1 0x1 0x2 0x3C
Partner's information:
LACP port Admin Oper Port Port
Port Flags Priority Dev ID Age key Key Number State
Et0/1 SA 32768 aabb.cc00.1a00 29s 0x0 0x1 0x2 0x3D
Age of the port in the current state: 0d:00h:04m:06sEtherchannel load balancing configuration
EtherChannel employs an algorithm to load-balance traffic effectively among the physical interfaces that form a logical interface in the etherchannel. This ensures that frames within the same flow traverse the network consistently using a designated physical interface.
For a detailed explanation about Etherchannel Load balancing, checkout our post on How to Configure Etherchannel Load Balancing.
Here is Etherchannel load balancing configuration on each of the swtiches;
Switch1
SW1(config)#port-channel load-balance src-dst-ip
SW1#show etherchannel load-balance
EtherChannel Load-Balancing Configuration:
src-dst-ip <--
EtherChannel Load-Balancing Addresses Used Per-Protocol:
Non-IP: Source XOR Destination MAC address
IPv4: Source XOR Destination IP address
IPv6: Source XOR Destination IP addressSwitch 2
SW2(config)#port-channel load-balance src-dst-ip
SW2#show etherchannel load-balance
EtherChannel Load-Balancing Configuration:
src-dst-ip <--
EtherChannel Load-Balancing Addresses Used Per-Protocol:
Non-IP: Source XOR Destination MAC address
IPv4: Source XOR Destination IP address
IPv6: Source XOR Destination IP addressRelated:
How to configure LACP etherchannel on Cisco switches in packet tracer
How to Configure Etherchannel Load Balancing
Reference: https://github.com/misterkrittin/CCNA-Labs
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