How to Configure Etherchannel Load Balancing in Packet Tracer

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. A “flow” is the path from one network device to another.

A flow in an etherchannel

Maintaining the order of frames within a flow is important. If frames from the same flow were distributed across different physical interfaces, the frames would arrive out of order at the destination, and this could potentially cause problems.

The calculation to determine the choice of a physical interface to use by etherchannel to forward frames takes several inputs into consideration. These could be source MAC addresses, destination MAC addresses, source and destination MAC addresses, source IP address, destination IP addresses, or source and destination IP addresses. The specific method employed by default depends on the switch model.  However, we can manually configure the switch to use a specific load-balancing operational state.

In this post, I will guide you on how to configure the Ethernet load-balancing method in packet tracer.

Network Topology

The network topology We will be making use of this post is shown below. As you can see, it consists of two layer 2 switches connected using an etherchannel. In this post, we will check the load-balancing operational state employed by the switch model and then configure it to use the source or destination IP addresses.

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network topology showing portchannel with trunk

Note: We have already completed Etherchannel configuration for the above network. Check it out if you are curious.

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Step 1: Check the default load-balancing state

Enter the following command to show the load balancing operational state employed by the switch model by default.

SW0#show etherchannel load-balance

Switch0

SW0#show etherchannel load-balance
EtherChannel Load-Balancing Operational State (src-mac):
Non-IP: Source MAC address
  IPv4: Source MAC address
  IPv6: Source MAC address

Switch1

SW1#show etherchannel load-balance
EtherChannel Load-Balancing Operational State (src-mac):
Non-IP: Source MAC address
  IPv4: Source MAC address
  IPv6: Source MAC address

As shown in the output of the show command above, the default load-balancing operational state used by the switch is “src-mac".

Step 2: Configure the load-balancing operation state

Enter the following command to change the load balancing operational state on each of the switch;

Switch0

SW0#configure terminal
SW0(config)#port-channel load-balance ?
  dst-ip       Dst IP Addr
  dst-mac      Dst Mac Addr
  src-dst-ip   Src XOR Dst IP Addr
  src-dst-mac  Src XOR Dst Mac Addr
  src-ip       Src IP Addr
  src-mac      Src Mac Addr

As shown above, we have multiple option to configure the load-balancing operational state. We will use ” src-dst-ip" in this demostration.

SW0(config)#port-channel load-balance src-dst-ip

Switch1

SW1#configure terminal
SW1(config)#port-channel load-balance ?
  dst-ip       Dst IP Addr
  dst-mac      Dst Mac Addr
  src-dst-ip   Src XOR Dst IP Addr
  src-dst-mac  Src XOR Dst Mac Addr
  src-ip       Src IP Addr
  src-mac      Src Mac Addr
SW1(config)#port-channel load-balance src-dst-ip

Step 3: confirm the configuration

Enter the show command again to confirm that the load-balancing operational state has been changed to “src-dst-ip” on each of the two switches.;

Switch0

SW0>enable 
SW0#show etherchannel load-balance
EtherChannel Load-Balancing Operational State (src-dst-ip):
Non-IP: Source XOR Destination MAC address
  IPv4: Source XOR Destination IP address
  IPv6: Source XOR Destination IP address

Switch1

SW1>enable
SW1#show etherchannel load-balance
EtherChannel Load-Balancing Operational State (src-dst-ip):
Non-IP: Source XOR Destination MAC address
  IPv4: Source XOR Destination IP address
  IPv6: Source XOR Destination IP address

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