Free CCNA | EtherChannel | Day 23 | CCNA 200-301 Complete Course

Welcome to Jeremy’s IT Lab

In this section, Jeremy introduces his IT Lab and the free CCNA course. He encourages viewers to subscribe, like, comment, and share the videos. The topic of this video is EtherChannel.

Introduction to EtherChannel

• EtherChannel allows grouping multiple physical interfaces into a single logical interface.

• Benefits of EtherChannel include increased bandwidth and improved network performance.

• This video covers configuring and verifying Layer 2 and Layer 3 EtherChannel using LACP (Link Aggregation Control Protocol).

What is EtherChannel?

In this section, Jeremy explains what EtherChannel is and the problems it solves, particularly related to spanning tree protocol.

Understanding EtherChannel

• EtherChannel groups multiple physical interfaces into a single logical interface.

• It helps overcome the limitations of spanning tree protocol that can cause congestion in network connections.

Configuring Layer 2 and Layer 3 EtherChannels

This section focuses on different methods of configuring both Layer 2 and Layer 3 EtherChannels.

Configuring Layer 2 and Layer 3 EtherChannels

• A Layer 2 etherchannel combines switch ports into a single interface.

• A Layer 3 etherchannel combines routed ports into a single interface with an assigned IP address.

Bonus Question from Boson Software's ExSim

Jeremy mentions a bonus question from Boson Software's ExSim practice exams for CCNA.

Bonus Question

• Watch until the end of the video for a bonus question from Boson Software's ExSim practice exams for CCNA.

Demonstration: Congestion Issue

Jeremy demonstrates a problem scenario where there is congestion between two switches due to insufficient bandwidth.

Congestion Issue

• Two switches, ASW1 and DSW1, are connected.

• The connection between ASW1 and DSW1 is congested due to multiple end hosts trying to access the Internet.

• Adding additional links does not resolve the congestion issue.

Understanding Oversubscription

This section explains oversubscription and its impact on network congestion.

Oversubscription

• Oversubscription occurs when the total bandwidth of interfaces connected to end hosts exceeds the bandwidth of connections to distribution switches.

• Excessive oversubscription leads to congestion issues.

The Problem with Multiple Links

Jeremy discusses the problem caused by multiple links between switches and how spanning tree protocol disables most of them.

Spanning Tree Protocol and Link Lights

• Spanning tree protocol disables all but one link when multiple links connect two switches.

• Checking the link lights, it is observed that only one link is active (green) while others are disabled (orange).

Solution: EtherChannel

This section introduces EtherChannel as a solution to enable redundancy and increase bandwidth in network connections.

Benefits of EtherChannel

• By forming physical interfaces into a logical interface using EtherChannel, redundancy and increased bandwidth can be achieved.

• EtherChannel groups multiple interfaces together, treating them as a single interface in terms of spanning tree protocol.

Verifying EtherChannel

Jeremy demonstrates how verifying link lights after configuring EtherChannel shows all links as active (green).

Verifying Link Lights

• After configuring EtherChannel, all link lights between ASW1 and DSW1 are green, indicating active connections.

New Section

This section explains how EtherChannel works as a single logical interface and how traffic is load balanced among the physical interfaces in the group.

EtherChannel as a Single Interface

• EtherChannel combines multiple physical interfaces into a single logical interface.

• DSW1 will only receive one copy of broadcast frames sent through the EtherChannel.

• ASW1 won't send multiple copies of the same broadcast frame out of a single interface.

Traffic Load Balancing

• Traffic using the EtherChannel is load balanced among the physical interfaces in the group.

• An algorithm determines which traffic will use which physical interface.

• DSW1 floods broadcast frames received from ASW1 out of all interfaces except the one it was received on.

• The other three interfaces in the EtherChannel won't forward the frame to avoid forming Layer 2 loops.

New Section

This section discusses how EtherChannel combines separate physical interfaces into a virtual interface and compares it to VLANs.

Virtual Interface

• Although there are four separate physical interfaces, they behave as a single virtual interface in an EtherChannel.

• The bandwidth of the four separate interfaces is combined to form one faster virtual interface.

• Understanding the difference between physical and logical/virtual characteristics is important for network engineers.

• VLANs virtually divide PCs into separate LANs, similar to how an EtherChannel forms a single virtual interface.

Other Names for EtherChannel

• Other names for an EtherChannel include Port Channel and Link Aggregation Group (LAG).

• Cisco IOS uses different terms to configure an EtherChannel.

New Section

This section explains what flows are and how they determine traffic forwarding within an EtherChannel.

Flows in Network Communication

• A flow represents communication between two nodes in the network.

• For example, a flow can be between PC1 and SRV1.

• Servers and printers are usually connected to access layer switches, not distribution layer switches.

Traffic Forwarding in Flows

• When PC1 initiates a data exchange with SRV1, frames are forwarded through the EtherChannel using a specific physical interface determined by an algorithm.

• Frames within the same flow will always be forwarded using the same physical interface to avoid out-of-order arrival at the destination.

• If PC1 initiates a separate flow with PR1, frames for that flow will use a different physical interface determined by another calculation.

New Section

This section explores how EtherChannel performs load balancing based on different flows and the inputs used in interface selection calculations.

Load Balancing Based on Flows

• EtherChannel load balances traffic among different flows using different physical interfaces in the group.

• The calculation to determine which physical interface to use considers various inputs.

Inputs for Interface Selection Calculation

• Source MAC address: Frames with the same source MAC address always use the same interface.

• Destination MAC address: Frames with the same destination MAC address always use the same interface.

• Both source and destination MAC addresses: Frames between specific nodes will use certain interfaces.

• Source IP address: Interface selection can also be based on source IP addresses.

New Section

This section discusses how to check and configure the load-balancing method for an EtherChannel.

Checking and Configuring Load-Balancing Method

• Use the command SHOW ETHERCHANNEL LOAD-BALANCE to see the current load-balancing method. The default for this switch model is to load balance based on source and destination IP addresses. Non-IP traffic uses source and destination MAC addresses.

• To change the load-balancing method, enter global config mode and use the command PORT-CHANNEL LOAD-BALANCE, followed by the desired method (e.g., source and destination MAC addresses).

• Available choices for load-balancing include MAC or IP addresses, with options to base it on either the source, destination, or both.

New Section

This section covers creating an EtherChannel between two switches using different configuration methods.

Configuration Methods for EtherChannel

1. PAgP (Port Aggregation Protocol):

• Cisco proprietary protocol used for dynamic negotiation of EtherChannel creation and maintenance.

• Only works with Cisco switches.

• Frames are sent to neighboring switch to determine if it wants to form an EtherChannel.

2. LACP (Link Aggregation Control Protocol):

• Industry standard protocol (IEEE 802.3ad) that dynamically negotiates EtherChannel creation and maintenance.

• Can be used with switches from other vendors.

3. Static EtherChannel:

• Interfaces are statically configured to form an EtherChannel without using a protocol for negotiation.

• Generally avoided as dynamic maintenance is preferred.

New Section

This section provides additional details on EtherChannel configuration and limitations.

Additional Configuration Details

• Up to 8 interfaces can be formed into a single EtherChannel (LACP allows up to 16, but only 8 will be active).

• Use the interface range command to configure all member interfaces at once for consistent configurations.

• To configure the EtherChannel, use the command CHANNEL-GROUP, followed by a number to identify the virtual interface, and specify the mode (e.g., PAgP or LACP).

Desirable Configuration and LACP

In this section, the speaker explains how to configure a desirable EtherChannel and introduces the Link Aggregation Control Protocol (LACP) for channel grouping.

Configuring a Desirable EtherChannel

• The virtual port-channel interface is created using the number specified in the channel-group command.

• The SHOW IP INTERFACE BRIEF command displays the virtual interface at the bottom of the output.

• The channel-group number must match between interfaces on the same switch but does not have to match on the other switch.

Introduction to LACP

• LACP uses "active" mode instead of "desirable" mode in EtherChannel configuration.

• LACP uses "passive" mode instead of "auto" mode in EtherChannel configuration.

• An EtherChannel will not be formed if both ends are configured as passive. Active-to-active or active-to-passive configurations will form an EtherChannel.

Static EtherChannel Configuration

This section covers static EtherChannel configuration and highlights important commands related to it.

Static EtherChannel Configuration

• Static EtherChannel uses only one mode: "ON".

• The CHANNEL-PROTOCOL command manually configures the negotiation protocol for member interfaces. However, it is not necessary to use this command as it is automatically determined based on the configured mode (PAgP or LACP).

Verification and Summary

This section focuses on verifying and summarizing EtherChannel configurations.

Verification of EtherChannels

• Use SHOW ETHERCHANNEL SUMMARY command to view a list of port-channel interfaces on the switch.

• S indicates Layer 2 etherchannel.

• U indicates that the etherchannel is active and being used.

• P indicates that physical ports are properly bundled in the port-channel.

Summary of EtherChannel Configuration

• Member interfaces in an EtherChannel must have matching configurations, including duplex setting, speed, switchport mode (access or trunk), allowed VLANs, and native VLAN.

• Trunk configurations applied to the port-channel interface are automatically applied to the physical interfaces as well.

• The port-channel interface can be verified using SHOW INTERFACES TRUNK command.

Conclusion

This section concludes the topic of EtherChannel configuration and provides a brief explanation of other flags that may appear in certain situations.

Conclusion

• Understanding how to configure desirable and static EtherChannels is important for network administrators.

• LACP provides an alternative negotiation protocol for channel grouping.

• Verifying EtherChannel status using SHOW ETHERCHANNEL SUMMARY command is useful for troubleshooting and monitoring purposes.

New Section

This section discusses the difference between the "S" flag and the upper-case "S" flag in EtherChannel. It also introduces the command SHOW ETHERCHANNEL PORT-CHANNEL to view information about the port-channel.

Difference between "S" Flag and Upper-case "S" Flag

• The lower-case "s" flag in EtherChannel indicates that a specific interface is suspended.

• The upper-case "S" flag means that the entire EtherChannel is suspended.

• In this case, only G0/0 is suspended while the EtherChannel still operates with three interfaces: G0/1, G0/2, and G0/3.

SHOW ETHERCHANNEL PORT-CHANNEL Command

• The command SHOW ETHERCHANNEL PORT-CHANNEL provides information about the number of ports in the port-channel and which protocol is being used.

New Section

This section highlights an important piece of information displayed by the command SHOW ETHERCHANNEL PORT-CHANNEL - the channel-group mode. It also emphasizes that SHOW ETHERCHANNEL SUMMARY is commonly used for EtherChannel configuration.

Channel-group Mode Displayed in SHOW ETHERCHANNEL PORT-CHANNEL

• The command SHOW ETHERCHANNEL PORT-CHANNEL displays additional information compared to SHOW ETHERCHANNEL SUMMARY.

• One important piece of information displayed is the channel-group mode, which can be active or another mode depending on configuration.

Importance of SHOW ETHERCHANNEL SUMMARY Command

• For EtherChannel configuration, one commonly used command is SHOW ETHERCHANNEL SUMMARY.

• This command provides a summary of all EtherChannels on the switch and their status.

New Section

This section explains how spanning-tree behaves when EtherChannel is configured. It clarifies that only the port-channel interface is listed, and the physical interfaces do not appear in the output of SHOW ETHERCHANNEL SUMMARY.

Spanning-Tree Behavior with EtherChannel

• When EtherChannel is configured, spanning-tree treats the four physical interfaces as a single logical interface.

• Instead of blocking three interfaces, all four can forward and receive traffic without concerns about Layer 2 loops.

• The output of SHOW ETHERCHANNEL SUMMARY only lists the port-channel interface, while the physical interfaces are not displayed.

New Section

This section briefly introduces Layer 3 EtherChannels and their advantages over Layer 2 connections. It mentions that ASW1 and DSW1 have been replaced with multilayer switches for this demonstration.

Advantages of Layer 3 Connections

• Modern network design often favors using Layer 3 connections between switches to avoid spanning-tree issues.

• With Layer 3 routed ports, multiple switches interconnected in a mesh can have all interfaces up and forwarding without disabling any due to spanning tree.

• Unlike Layer 2 EtherChannels, where spanning-tree may still block ports in a looped connection scenario, routed ports prevent Layer 2 loops from forming.

New Section

This section clarifies that even with EtherChannel configured, Layer 2 loops can occur if multiple switches are connected together in a loop. It emphasizes that using routed ports instead of Layer 2 switchports eliminates the need for spanning-tree altogether.

Potential for Layer 2 Loops with Multiple Switches

• Even when using EtherChannel, if multiple switches are connected together in a loop configuration, layer 2 loops can still occur.

• Spanning-tree will block one of the port-channel interfaces to prevent broadcast storms caused by looping broadcasts.

Eliminating Spanning-Tree with Routed Ports

• If all connections between switches are made using routed ports instead of Layer 2 switchports, spanning-tree is not required.

• Routed ports do not forward Layer 2 broadcasts, preventing the formation of Layer 2 loops.

New Section

This section explains how to configure Layer 3 EtherChannels and highlights the importance of configuring IP addresses on the port-channel interface.

Configuring Layer 3 EtherChannels

• To configure a Layer 3 EtherChannel, start with a clean configuration without any configured port-channels.

• Enter interface range config mode for the member interfaces and use the NO SWITCHPORT command to make them Layer 3 routed interfaces.

• After using the CHANNEL-GROUP command, check the configuration using SHOW RUNNING-CONFIG. The port-channel interface will automatically have the NO SWITCHPORT command applied to it.

IP Address Configuration

• For a Layer 3 EtherChannel, an IP address should be configured on the port-channel interface.

• Use SHOW ETHERCHANNEL SUMMARY to view information about the EtherChannel configuration, including the "R" flag indicating a Layer 3 EtherChannel.

• The output of SHOW IP INTERFACE BRIEF displays the IP address configured on port-channel 1.

New Section

This section emphasizes that traffic will be load-balanced over all member interfaces in both Layer 2 and Layer 3 EtherChannels. It provides a quick review of commands covered in this topic.

Load-Balancing in Both Layer 2 and Layer 3 EtherChannels

• Similar to Layer 2 EtherChannels, traffic in a Layer 3 EtherChannel will be load-balanced over all member interfaces.

Review of Commands Covered

• PORT-CHANNEL LOAD-BALANCE: Command used to configure load-balancing options for an EtherChannel.

• CHANNEL-GROUP: Command used to configure an interface to be part of an EtherChannel.

• SHOW ETHERCHANNEL SUMMARY: Command used to display a summary of all EtherChannels on the switch and their status.

• SHOW ETHERCHANNEL PORT-CHANNEL: Command used to view detailed information about the port-channel interfaces on the switch.

New Section

This section concludes by stating that while there are more commands available for EtherChannel configuration, understanding the basic purpose, setup, and verification is sufficient.

Conclusion

• While there are many more commands available for EtherChannel configuration, a basic understanding of its purpose and how to set it up and verify its status is sufficient.

EtherChannel Configuration

This section discusses the configuration options for EtherChannel and the correct settings to form an EtherChannel.

EtherChannel Modes

• EtherChannel modes include on-on, desirable-auto, and active-active.

• The correct modes to form an EtherChannel are on-on, desirable-auto, and active-active.

• Mixing different modes such as active-desirable or on-desirable will not result in a valid EtherChannel configuration.

Show EtherChannel Summary

• The flag (P) next to physical interfaces in the show etherchannel summary command indicates that they are bundled in the port-channel.

• This flag is desired for member interfaces of an EtherChannel.

Member Interface Parameters

• To form an EtherChannel, interface speed and switchport mode (access or trunk) need to match.

• Interface ID and IP address do not need to match for forming an EtherChannel.

EtherChannel Configuration Example

This section presents a practice question about configuring EtherChannels between two switches.

SwitchA Configuration

• SwitchA creates a virtual port-channel interface using INTERFACE PORT-CHANNEL 1 command.

• FastEthernet 0/5 and 6 are manually configured with LACP negotiation protocol using INTERFACE RANGE command.

• CHANNEL-GROUP 1 MODE ON command is used to configure static protocol for the port-channel interface.

SwitchB Configuration

• Similar to SwitchA, SwitchB creates a virtual port-channel interface beforehand.

• FastEthernet 0/5 and 6 are manually configured with PAgP negotiation protocol using INTERFACE RANGE command.

• CHANNEL-GROUP 1 MODE ON command is used to configure static protocol for the port-channel interface.

Resulting EtherChannel Link

• No link is formed between SwitchA and SwitchB because the CHANNEL-GROUP 1 MODE ON command is rejected due to conflicting negotiation protocols (LACP and PAgP).

Conclusion

The transcript covers the configuration options for EtherChannel, including the different modes and parameters required to form an EtherChannel. It also provides an example scenario of configuring EtherChannels between two switches and explains why a link may not be formed in certain cases.

EtherChannel and Boson ExSim Overview

In this section, the speaker discusses EtherChannel and recommends Boson ExSim as a study resource for CCNA and CCNP exams.

EtherChannel Coverage in Official Cert Guide

• The topic of EtherChannel is covered in Volume 1, Chapter 10 of the Official Cert Guide.

• The Official Cert Guide is a recommended study resource for understanding EtherChannel.

Cisco Documentation Links

• Two links to Cisco documentation are provided as additional study resources.

• These links are freely available online and can be accessed for further information on EtherChannel.

Recommendation: Boson ExSim Practice Exams

• The speaker highly recommends using Boson ExSim practice exams for preparing for CCNA and CCNP exams.

• They personally used these practice exams and found them helpful.

• To obtain a copy of Boson ExSim, viewers can follow the link provided in the video description.

Supplementary Materials Overview

This section highlights supplementary materials available for studying, including flashcards and packet tracer practice labs.

Anki Flashcard Deck

• A flashcard deck is available to use with the software 'Anki'.

• This flashcard deck can be used as a study aid along with the course material.

Packet Tracer Practice Lab

• A packet tracer practice lab will be provided in the next video.

• This lab offers hands-on practice to reinforce learning concepts.

Accessing Supplementary Materials

• Viewers are encouraged to sign up for the mailing list via the link in the video description.

• By signing up, viewers will receive all flashcards and packet tracer lab files related to the course.

Acknowledgements Overview

The speaker expresses gratitude towards JCNP-level channel members who support the channel.

Thanking JCNP-level Channel Members

• The speaker extends thanks to various JCNP-level channel members for their support.

• Names of the members are mentioned, acknowledging their contributions.

• Apologies are given for any mispronunciations of names.

Closing Remarks Overview

The speaker concludes the video and encourages viewers to subscribe, like, comment, and share the video. Tips and additional information are also provided.

Incomplete Channel Loading Issue

• The speaker mentions that one channel is still displaying as "Channel failed to load."

• They request the affected individual to inform them so that YouTube can address the issue.

Closing Message and Call-to-Action

• Viewers are thanked for watching and encouraged to subscribe, like, comment, and share the video.

• Links in the description provide options for leaving tips or supporting the channel through BAT (Basic Attention Token).