Introduction
Have you ever faced a scenario where you want more bandwidth than what your network link can provide? Or have you ever experienced a network outage because of a single link failure? If yes, then you are probably interested in EtherChannel. It is a port link aggregation technology that groups together more than one physical Ethernet link to create one logical Ethernet link for the purpose of providing fault-tolerance and high-speed links between switches, routers, and servers.
In this blog, we will explain EtherChannel in networking, its purpose, and the different protocols it uses in detail.
What is EtherChannel?
EtherChannel is a port-channel architecture or port-link aggregation technology that is predominantly utilized on Cisco switches. For the aim of providing fault-tolerance and fast connectivity between switches, routers, and servers, it enables the grouping of numerous physical Ethernet links into one logical Ethernet link.
Only 8 interfaces can be active at once while using EtherChannel, which can combine up to 16 physical interfaces into a single logical interface. If any of the active interfaces fails, the other 8 interfaces can switch from standby to active mode. Switches, routers, and servers consider the logical interface as a single entity, and traffic is divided among the physical interfaces in the group.
Below, you can see the image for a better understanding.
To create an EtherChannel in Networking, all of the interfaces in the group should have:
- Same duplex
- Switch port modes should be the same
- Same speed
- Same VLAN configuration
EtherChannel can use different algorithms to decide which physical interface to send traffic over, such as:
- Source MAC address
- Destination MAC address
- Source and destination MAC address
- Source IP address
- Destination IP address
- Source and destination IP address
- Source TCP/UDP port
- Destination TCP/UDP port
- Source and destination TCP/UDP port
Purpose of EtherChannel in Networking
It’s primary function is to offer redundant, fast connections between network devices. We can profit from utilizing EtherChannel in networking in the following ways:
Increased Bandwidth
Since EtherChannel may aggregate or combine traffic across all active links in the group, it appears to be a single, higher-bandwidth logical cable. For instance, we can utilize it to turn a pair of switches’ four 100 Mbps links into a single logical link with 400 Mbps of capacity.
Improved Redundancy
It can offer fault tolerance by way of mechanically switching traffic to some other active link within the group if one link fails. In this manner, we will avoid dropping connectivity or data between network devices. For example, if one of the four one hundred Mbps links between two switches fails, EtherChannel will still keep a 300 Mbps logical link between them.
Enhanced Load Balancing
It can distribute traffic across more than one physical link in the group primarily based on distinctive standards, such as MAC address or IP address. In this manner, we can easily avoid congestion or bottlenecks on a single link and improve the overall performance of our network. For instance, if we’ve got different types of traffic with different source and destination addresses, it will send them over links to different links in the group.
How Does EtherChannel Work?
EtherChannel in Networking works by using special protocols that negotiate and establish the link aggregation between devices. The protocols that are used in EtherChannel configuration are:
PAgP (Port Aggregation Protocol)
It is possible to dynamically negotiate and create an EtherChannel between two devices using the Cisco-proprietary PAgP protocol. In order to determine whether two devices are compatible and willing to build an EtherChannel, PAgP uses an exchange of messages between them called packets.
The two modes of PAgP are Desirable and Auto. The device actively initiates and requests to build an EtherChannel with another device when it is in the desirable mode. The device waits passively for another device to begin and requests to form an EtherChannel when it is in auto mode.
Both devices must have at least one interface in the desirable mode or both interfaces in auto mode in order to form an EtherChannel using PAgP, as you can see in the image below for better understanding.
LACP (Link Aggregation Control Protocol)
We may dynamically negotiate and form an EtherChannel between two devices made by different vendors with the help of the LACP protocol, which is an IEEE standard protocol. Similar to PAgP, LACP tests the compatibility and willingness of the devices to form an EtherChannel by exchanging messages called frames between them.
The three modes of LACP are active, passive, and on. In active mode, the device requests to form an EtherChannel with another device and actively starts the request. The device waits passively for another device to begin and requests the formation of an EtherChannel in networking while it is in passive mode. In “on” mode, the device assumes that an EtherChannel is there without engaging in any communication or negotiation with another device. In on mode, the device does not negotiate or exchange any messages with another device but simply assumes that it exists.
Both devices must have at least one active interface, or one active interface and one passive interface, in order to create an EtherChannel utilizing LACP. We have shown in the image below for better understanding.
How to Configure EtherChannel on Cisco Devices?
EtherChannel can be configured on Cisco switches using CLI (Command Line Interface). We have discussed the steps for setting up static and dynamic EtherChannel below.
Step 1: Verify Interface Compatibility
You should ensure a few things before configuring EtherChannel:
- All the ports have the same speed and duplex settings.
- The interface is part of the same VLAN.
- There are no conflicting configurations.
Step 2: Configure Static EtherChannel
To manually configure EtherChannel without a negotiation protocol:
interface range GigabitEthernet1/0/1 – 2
channel-group 1 mode on
exit
Step 3: Configure LACP-based EtherChannel
To use LACP for automatic link aggregation:
interface range GigabitEthernet1/0/1 – 2
channel-group 1 mode active
exit
- mode active – It enables LACP on the interfaces.
Step 4: Configure PAgP-based EtherChannel
For PAgP configuration on Cisco switches:
interface range GigabitEthernet1/0/1 – 2
channel-group 1 mode desirable
exit
- mode desirable – It enables automatic negotiation with other Cisco devices.
Step 5: Verify Configuration
After configuration, verify EtherChannel status with:
show etherchannel summary
This command displays active ports, protocol type, and link status.
Benefits of Using EtherChannel
The inclusion of EtherChannel to a network brings numerous benefits to the overall performance and reliability of the system. Here are its benefits:
1. Enhanced Bandwidth
Multiple links can be merged into an EtherChannel, increasing the width of a trunk. For instance, merging four one Gb links will result in four Gbps throughput.
2. Redundancy and Failover Support
EtherChannel helps to decrease the vast amount of down time that could be accumulated due to network outages. For example:
- Traffic can still flow when one link goes down as the rest of the available links in the bundle remain active.
- Service availability is maintained due to traffic continually being re-distributed to the active links.
3. Improved Performance and Decreased Congestion
EtherChannel distributed traffic across multiple links, thus preventing network performance and preventing network congestion. Instead of one path performing all the work, load balancing takes place where all paths contribute to achieving a goal.
4. Ease of Network Management
Networking administrators have an easier time tracking an EtherChannel interface rather than multiple individual links. This helps to lower the complexity, which makes troubleshooting remarkably easier.
5. Compatibility with Spanning Tree Protocol (STP)
EtherChannel assists in reducing the amount of blocked links in Spanning Tree Protocol, as it treats the EtherChannel bundle like a single logical link. This enables all links to remain unblocked without causing loops in the network.
These are some benefits offered by EtherChannel.
EtherChannel vs STP (Spanning Tree Protocol)
Here are the difference between EtherChannel and STP:
| Feature | EtherChannel | STP |
|---|---|---|
| Purpose | Groups links to enhance bandwidth | Avoids loops in a network |
| Redundancy | Provides failover within the bundle | Blocks redundant links |
| Efficiency | Employs all links within bundle | Restricts some links to reduce loop |
| Use Case | High-performance networks needing load balancing | Large Networks prone to loops |
Note: EtherChannel works alongside STP to prevent loops while ensuring maximum link utilization.
Real-World Applications of EtherChannel
EtherChannel has numerous real life applications in enterprise, data centers, and cloud computing technologies to enhance network efficiency, flexibility, and reliability.
1. Data centers and enterprise networks
- EtherChannel is useful for the high-speed backbone connections within the core, distribution and access layers of enterprise networks.
- EtherChannel is also used for load balancing and redundancy of server-to-switch connections.
2. Service provider networks
- ISPs use EtherChannel to bundle multiple links between a router and switch, increasing bandwidth available to customers.
- Provides an improved WAN connection by combining multiple circuits into a single logical circuit.
3. Cloud computing environments
- In cloud data centers, EtherChannel is used to connect virtualized environments with physical switches.
- Offers seamless failover and uninterrupted service for cloud applications.
Frequently Asked Questions
Q1. What are the 3 types of EtherChannel?
Three types of EtherChannel in networking are:
- PAgP: It is a Cisco-proprietary protocol.
- LACP: IEEE Standard Protocol.
- Manual: It is manually configured on each switch.
Q2. What do you mean by EtherChannel?
EtherChannel is a link aggregation technology that is mainly used to link more than one physical port link into a single logical link.
Q3. What is port channel vs EtherChannel?
A port channel is a logical interface that represents a group of physical links aggregated together. EtherChannel in networking is a Cisco term for link aggregation technology that bundles multiple links into one logical link.
Q4. Why is LACP used?
LACP is used to combine multiple physical links into one logical link for higher bandwidth and redundancy.
Conclusion
EtherChannel is a powerful feature that allows us to combine multiple physical links into one logical link, increasing the bandwidth and redundancy of the network. In this blog, we have explained EtherChannel in networking along with its purpose and how it works.
If you have any queries, feel free to comment below.
