EtherChannel Basic Concepts and Fundamentals Explained | EtherChannel Modes and Options
This tutorial explains the following topics.
What is an EtherChannel?
How does an EtherChannel work?
What are the EtherChannel modes?
Differences between Static, LACP, and PAgP modes
How EtherChannel works with STP
What is an EtherChannel pool?
EtherChannel load balancing rules
How does EtherChannel load-balancing work?
EtherChannel Types
EtherChannel Requirements
This tutorial is based on the following tutorials.
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EtherChannel Basic Concepts and Fundamentals
An EtherChannel is a group of links that work together as a single link. Administrators use EtherChannels for various reasons. The two most common reasons for using EtherChannels are they offer higher bandwidth and provide redundancy for critical network resources.
EtherChannel V/s Port Channel V/s Channel Group
The terms EtherChannel, Port Channel, and Channel-group are synonymous. They all refer to the same thing. A switch can use any one or all terms to refer to EtherChannel and its functions. For example, Cisco switches use the term channel-group for the EtherChannel configuration command, the term EtherChannel for the EtherChannel configuration display command, and the term Port Channel to refer to EtherChannel in the output of the EtherChannel configuration display command.
Type of EtherChannel
There are two types of EtherChannels: Static and Dynamic. Static EtherChannel needs manual configuration. Dynamic EtherChannel uses an EtherChannel protocol. The protocol dynamically adds and manages links in the EtherChannel. There are two EtherChannel protocols: LACP and PAgP.
Link Aggregation Control Protocol (LACP)
IEEE developed LACP as an 802.3ad standard. It is an open standard protocol. It works with all vendors' switches. It can combine up to 16 links. However, it uses only 8 of them at a given time. It keeps remaining in the waiting. If any active link fails, it adds a waiting link to the pool.
Port Aggregation Protocol (PAgP)
Cisco developed PAgP as a proprietary protocol. It works only on Cisco switches. It can combine up to 8 links. It works similarly to LACP but uses different terms for its modes.
Cisco switches support both protocols. You can use anyone you want. However, you can't PAgP on non-Cisco switches.
EtherChannel Restrictions/Requirements
No matter which configuration method you choose, all EtherChannels have some restrictions. You can't add any port to an EtherChannel. All ports in an EtherChannel must have the same Speed, Duplex, Port type, VLAN and Trunk states, and STP settings.
EtherChannels allow you to combine up to eight physical interfaces into a single virtual interface. For example, you can combine:-
Up to eight Fast Ethernet connections, providing up to 800 Mbps
Up to eight Gigabit Ethernet connections, providing up to 8 Gbps
Up to eight 10-Gigabit Ethernet connections, providing up to 80 Gbps
You can have a total of six EtherChannels on a switch. Interfaces in an EtherChannel must use identically speed, duplexing, and VLAN settings. Interfaces in an EtherChannel appear as a single interface for STP.