It is called link aggregation. It is used to aggregate multiple physical links into a single logical link. That logical link is called a port channel.

What are the requirements of Etherchannel?

  • Duplex must match.
  • The speed must match.
  • Etherchannel standard must match.
  • Trunk allowed VLAN list must match.
  • Native VLAN must match.
  • Tunk encapsulation protocol must match.
  • Prunning eligibility list must match.
  • After creating EtherChannel stp will not work for switchport which are a member of the port channel.

How many types of EtherChannel are there?

  • Static
  • Pagp: – It stands for port aggregation protocol. It is a Cisco proprietary protocol. It aggregates up to 8 links. Modes    1. Auto   2. Desirable.

Pagp directional mode

 Silent: -It will create a portchannel without checking bidirectional connectivity for every port.

          Non-Silent:  – It will check bidirectional connectivity for every port, both sides need 

            It is used for fiber-optic.

  • Lacp: – It stands for link aggregation control protocol. It is an open standard protocol. It can aggregate up to 16 links in a single channel group. Only 8 links will participate actively at a time.

Modes of lacp  

1. Active   

2. Passive.

Lacp sys-id

The main switch will elect using lacp system id(lower). That main switch will elect an active port by using port id and it will negotiate with the neighbor.

Election of the Main switch

  1. Sys- priority (default 32768)
  2. Sys- mac (base mac)

                  Lacp port-id: – it will elect an active port and negotiate with the neighbor.

 Election of active port

  1. Port – priority (default 32768)
  2. Interface-id

   What is the EtherChannel load-balancing algorithm?

  1. Source mac
  2. Destination mac
  3. Source and destination mac
  4. Source ip address
  5. Destination ip address
  6. Source and destination ip address
  7. Source port number
  8. Destination port number
  9. Source and destination port number


 Switch (config-if-range) # channel group 10 mode on

 Switch# show EtherChannel

 Switch# show etherchannel summary

 Switch# show interface port channel 10

 Switch# show spanning tree

 Switch# show ip interface brief

 Switch# show etherchannel load-balancing


 (Config-if-range) # channel-group 20 mode desirable/non-silent

 Switch(config-if-range) # channel group 20 mode auto


Switch (config-if-range) # channel-group 20 mode active

Switch (config-if-range) # channel-group 20 mode passive

Switch# show etherchannel

Switch# show lacp sys-id

Switch# show lacp internal

Switch(config)# lacp system priority (1-65535)

Switch(config-if) # lacp port priority (0-65535)

Switch(config)# port channel load-balancing?

  Layer 3 EtherChannel

If there are 8 links in EtherChannel then 8 neighborship will be established. There is 8     neighbors’ entry on the neighbor table. If any port goes down, the neighborship will down. If we have 8 links then we must give ip in 8 subnets. CPU utilization is more. To solve this problem, we have a layer 3 EtherChannel.


 Switch1 (config-if-range) # no switchport

 Switch1 (config-if-range) # channel-group 20 mode on/desirable/active

 Switch1 (config-if-range) # no switchport

 Switch1 (config-if-range) # channel-group 20 mode on/auto/passive

 Switch1 (config)# interface port-channel 20

 Switch1 (config-if) # ip address

 Switch1 (config-if) # no shutdown

 Switch1 (config)# interface port-channel 20

 Switch1 (config-if) # ip address

 Switch1 (config-if) # no shutdown

  Zindagi Technology is a lead IT consulting company. We have successfully completed lots of IT projects. We provide IT solutions like cyber security, planning, designing, and implementation of data centers, cloud-based services, and application development, etc. we can assist you in your network programs. You can ping us at +91-9773973971 and email us.

Lokesh Kumar
Associate Consultant

Comment (1)

  1. Avatar photo
    Saikumar VRK
    November 27, 2021

    Nice information and thanks for sharing,
    Please clarify why two IP addresses are assigned to interface port-channel 20 in configuration of Layer3 Ether channel?

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