Layer 3 EtherChannel: Secrets to Fast and Reliable Networks
Introduction
Are you looking to make your network faster, more reliable, and more resilient? Let us dive into Layer 3 Etherchannel! There are two main types of etherchannel, which are layer 2 and layer 3 etherchannel. Layer 2 is configured on layer two devices, such as layer 2 switches, while layer 3 link aggregation operates at the network layer (layer 3 switches or routers), which allows multiple networks or subnets for routing.
What is a Layer 3 Etherchannel?
Layer 3 etherchannel bundles multiple physical interfaces together to form a single logical interface at the network layer, enabling our network to handle higher traffic loads with improved redundancy.
While layer 2 etherchannel is limited to switch-to-switch, layer 3 etherchannel enables routing between multiple subnets, which significantly increases the network’s efficiency and resiliency. It also improves network throughput, reduces latency, and reduces redundancy.
Each link in the layer 3 aggregation will be treated as routed ports, which means it will use an IP address.
Lab topology
The following lab topology will consist of a Layer 3 link aggregation configuration. The two switches lab has been configured in Packet Tracer.
Configure the basic settings on each switch, such as hostname, domain name, and server mode.
Now configure layer 3 etherchannel on each switch as given below in the screenshot. The interface ranges from Fa 0/1 to Fa 0/4. After entering interface mode, shut it down and then run the command “no switchport,” which disables the Layer 2 switching functionality on the interfaces and converts the interfaces into a Layer 3 interface.
Remove the ip address if previously configured on it with the “no IP address” command, and then add the interfaces to a port channel by setting its mode to “on.” The “on” mode means that link aggregation will be statically configured and the interfaces will be part of the port channel without any negotiation protocol like LACP or PAgP. Moreover, set the IP address of each port-channel on both switches for connectivity.
Again, shut down all interfaces of both the switches.
Our configuration has been completed for layer 3 aggregation. Now run the command on switch1: show etherchannel summary”. It displays the status and configuration of the Etherchannel, such as port-channel interfaces, protocol, status, and mode.
Another command, “show etherchannel,” displays the number of etherchannel groups configured on switch1. It tells whether the aggregating links are layer 2 or layer 3. Moreover, it shows the channel group number, or port-channel , which is “1”.
As our Etherchannel is Layer 3, so its state is “L3.” At last, we configured layer 3 etherchannel in a static way; that’s why it is not showing any protocol like LACP or PagP!
After all, ping from Switch1 to Switch2 for connectivity!
The Switch1 has successfully pinged Switch2, which shows the correct configuration of the Layer Three Aggregation!
For more information about aggregation, check our blog.
