EtherChannel
Work in progress.

EtherChannel #

What is EtherChannel? #

EtherChannel is a technology that allows multiple physical links between two devices to be aggregated into one logical link. The logical link created by EtherChannel appears as a single connection to the network layer, even though it is made up of several physical connections. EtherChannel allows the bandwidth of multiple physical links to be combined, increasing the overall bandwidth of the logical link.

Benefits of EtherChannel #

EtherChannel offers several benefits:

  1. Combines multiple physical links into a single logical link, increasing overall bandwidth.

  2. Distributes traffic across multiple physical links to prevent congestion.

  3. Provides redundancy by rerouting traffic over surviving links if one link fails.

  4. Simplifies network design by presenting multiple physical links as a single logical link.

EtherChannel Configuration #

EtherChannel can be configured using two protocols: Link Aggregation Control Protocol (LACP) and Port Aggregation Protocol (PAGP).

LACP #

LACP is an IEEE standard protocol that allows devices to automatically detect and configure EtherChannels. When using LACP, a device sends LACP packets to its neighbor to negotiate the creation of an EtherChannel. If both devices agree, the EtherChannel is formed.

We have two LACP modes, and these are the following:

LACP Mode Description
Active The device actively sends LACP packets to the other end to form a link aggregation group (LAG). It negotiates with the other end to determine the characteristics of the LAG, such as the number of links, the link speed, and the load-balancing algorithm to use. Active mode can initiate and receive LACP negotiations.
Passive The device responds to LACP packets sent by the active mode device. The passive mode device does not initiate LACP negotiations, but it can still participate in the negotiation process by accepting or rejecting the requests sent by the active device.

LACP has the following minimum requirements that must be met for LACP to work.

  1. LACP support on all devices involved in link aggregation
  2. Same link speed and duplex mode
  3. Switchport mode is the same (access or trunk)
  4. Consistent VLAN configuration

LACP Configuration: #

The following steps can be used to configure LACP for EtherChannel:

Step 1: Enable EtherChannel on the interfaces

interface range GigabitEthernet0/1 - 4
channel-group 1 mode active

Step 2: Configure the LACP protocol on the EtherChannel interface

interface port-channel 1
switchport mode trunk
channel-protocol lacp

Step 3: Configure the LACP mode

interface port-channel 1
channel-group 1 mode active