ME 3800x and ME 3600x Switches Software Configuration Guide, Release 15.2(4)S
Configuring EtherChannels
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Configuring EtherChannels

Table Of Contents

Configuring EtherChannels

Understanding EtherChannels

EtherChannel Overview

Port-Channel Interfaces

Port Aggregation Protocol

PAgP Modes

PAgP Interaction with Other Features

Link Aggregation Control Protocol

LACP Modes

LACP Interaction with Other Features

EtherChannel On Mode

Load Balancing and Forwarding Methods

Configuring EtherChannels

Default EtherChannel Configuration

EtherChannel Configuration Guidelines

Configuring Layer 2 EtherChannels

Configuring Layer 3 EtherChannels

Creating Port-Channel Logical Interfaces

Configuring the Physical Interfaces

Configuring EtherChannel Load Balancing

Configuring the PAgP Learn Method and Priority

Configuring LACP Hot-Standby Ports

Configuring the LACP System Priority

Configuring the LACP Port Priority

Configuring the EtherChannel Min-Links Feature

EtherChannels and Ethernet Flow Points (EFPs)

Displaying EtherChannel, PAgP, and LACP Status


Configuring EtherChannels


This chapter describes how to configure EtherChannels on Layer 2 and Layer 3 ports on the Cisco ME 3800X and ME 3600X switch. EtherChannel provides fault-tolerant high-speed links between switches, routers, and servers. You can use it to increase the bandwidth between the wiring closets and the data center, and you can deploy it anywhere in the network where bottlenecks are likely to occur. EtherChannel provides automatic recovery for the loss of a link by redistributing the load across the remaining links. If a link fails, EtherChannel redirects traffic from the failed link to the remaining links in the channel without intervention.


Note Although EtherChannels are not supported on ports configured with service instances, you can configure a service instance on an EtherChannel port channel.


For complete syntax and usage information for the commands used in this chapter, see the command reference for this release.

Understanding EtherChannels

Configuring EtherChannels

Displaying EtherChannel, PAgP, and LACP Status

Understanding EtherChannels

EtherChannel Overview

Port-Channel Interfaces

Port Aggregation Protocol

Link Aggregation Control Protocol

EtherChannel On Mode

Load Balancing and Forwarding Methods

EtherChannel Overview

An EtherChannel consists of individual ports bundled into a single logical link as shown in Figure 35-1.

Figure 35-1 Typical EtherChannel Configuration

The EtherChannel provides full-duplex bandwidth of up to 800 Mbps between your switch and another switch or host for Fast EtherChannel on a switch with 24 Fast Ethernet ports. For Gigabit EtherChannel, you can configure up to 8 Gbps (8 ports of 1 Gbps), depending on the number of supported Gigabit Ethernet interfaces.

Each EtherChannel can consist of up to eight compatibly configured Ethernet ports. All ports in each EtherChannel must be configured as either Layer 2 or Layer 3 ports. The number of EtherChannels is limited to 48. For more information, see the "EtherChannel Configuration Guidelines" section. The EtherChannel Layer 3 ports are made up of routed ports. Routed ports are physical ports configured to be in Layer 3 mode by using the no switchport interface configuration command. For more information, see the Chapter 10 "Configuring Interfaces."

You can configure an EtherChannel in one of these modes: Port Aggregation Protocol (PAgP), Link Aggregation Control Protocol (LACP), or On mode. Configure both ends of the EtherChannel in the same mode:

When you configure one end of an EtherChannel in either PAgP or LACP mode, the system negotiates with the other end of the channel to determine which ports should become active. Incompatible ports are suspended.

When you configure an EtherChannel in the on mode, no negotiations take place. The switch forces all compatible ports to become active in the EtherChannel. The other end of the channel (on the other switch) must also be configured in the on mode; otherwise, packet loss can occur.

The local port is put into an independent state and continues to carry data traffic as would any other single link. The port configuration does not change, but the port does not participate in the EtherChannel.

If a link within an EtherChannel fails, traffic previously carried over that failed link changes to the remaining links within the EtherChannel. A trap is sent for a failure, identifying the switch, the EtherChannel, and the failed link. Inbound broadcast and multicast packets on one link in an EtherChannel are blocked from returning on any other link of the EtherChannel.

Port-Channel Interfaces

When you create an EtherChannel, a port-channel logical interface is involved:

With Layer 2 ports, use the channel-group interface configuration command to dynamically create the port-channel logical interface.

You also can use the interface port-channel port-channel-number global configuration command to manually create the port-channel logical interface, but then you must use the channel-group channel-group-number command to bind the logical interface to a physical port. The channel-group-number can be the same as the port-channel-number, or you can use a new number. If you use a new number, the channel-group command dynamically creates a new port channel.

With Layer 3 ports, you should manually create the logical interface by using the interface port-channel global configuration command followed by the no switchport interface configuration command. Then you manually assign an interface to the EtherChannel by using the channel-group interface configuration command.

For both Layer 2 and Layer 3 ports, the channel-group command binds the physical port and the logical interface together as shown in Figure 35-2.

Each EtherChannel has a port-channel logical interface numbered from 1 to 48. This port-channel interface number corresponds to the one specified with the channel-group interface configuration command.

Figure 35-2 Relationship of Physical Ports, Logical Port Channels, and Channel Groups

After you configure an EtherChannel, configuration changes applied to the port-channel interface apply to all the physical ports assigned to the port-channel interface. Configuration changes applied to the physical port affect only the port to which you apply the configuration. To change the parameters of all ports in an EtherChannel, apply the configuration commands to the port-channel interface.

Port Aggregation Protocol

The Port Aggregation Protocol (PAgP) is a Cisco-proprietary protocol that can be run only on Cisco switches and on those switches licensed by vendors to support PAgP. PAgP facilitates the automatic creation of EtherChannels by exchanging PAgP packets between Ethernet ports.

By using PAgP, the switch learns the identity of partners capable of supporting PAgP and the capabilities of each port. It then dynamically groups similarly configured ports into a single logical link (channel or aggregate port). Similarly configured ports are grouped based on hardware, administrative, and port parameter constraints. For example, PAgP groups the ports with the same speed, duplex mode, native VLAN, VLAN range, and trunking status and type. After grouping the links into an EtherChannel, PAgP adds the group to the spanning tree as a single switch port.

PAgP Modes

Table 35-1 shows the user-configurable EtherChannel PAgP modes for the channel-group interface configuration command on an port.

Table 35-1 EtherChannel PAgP Modes 

Mode
Description

auto

Places a port into a passive negotiating state in which the port responds to PAgP packets it receives but does not start PAgP packet negotiation. This setting minimizes the transmission of PAgP packets.

desirable

Places a port into an active negotiating state in which the port starts negotiations with other ports by sending PAgP packets.


Switch ports exchange PAgP packets only with partner ports configured in the auto or desirable modes. Ports configured in the on mode do not exchange PAgP packets.

Both the auto and desirable modes enable ports to negotiate with partner ports to form an EtherChannel based on criteria such as port speed and, for Layer 2 EtherChannels, trunking state and VLAN numbers.

Ports can form an EtherChannel when they are in different PAgP modes as long as the modes are compatible. For example:

A port in the desirable mode can form an EtherChannel with another port that is in the desirable or auto mode.

A port in the auto mode can form an EtherChannel with another port that is in the desirable mode.

A port in the auto mode cannot form an EtherChannel with another port that is also in the auto mode because neither port starts PAgP negotiation.

If your switch is connected to a partner that is PAgP-capable, you can configure the switch port for nonsilent operation by using the non-silent keyword. If you do not specify non-silent with the auto or desirable mode, silent mode is assumed.

Use the silent mode when the switch is connected to a device that is not PAgP-capable and seldom, if ever, sends packets. An example of a silent partner is a file server or a packet analyzer that is not generating traffic. In this case, running PAgP on a physical port connected to a silent partner prevents that switch port from ever becoming operational. However, the silent setting allows PAgP to operate, to attach the port to a channel group, and to use the port for transmission.

PAgP Interaction with Other Features

Cisco Discovery Protocol (CDP) sends and receives packets over the physical ports in the EtherChannel.

Trunk ports send and receive PAgP protocol data units (PDUs) on the lowest numbered VLAN.

In Layer 2 EtherChannels, the first port in the channel that comes up provides its MAC address to the EtherChannel. If this port is removed from the bundle, one of the remaining ports in the bundle provides its MAC address to the EtherChannel.

PAgP sends and receives PAgP PDUs only from ports that are up and have PAgP enabled for the auto or desirable mode.

Link Aggregation Control Protocol

The LACP is defined in IEEE 802.3ad standard and enables Cisco switches to manage Ethernet channels between switches that conform to the standard. LACP facilitates the automatic creation of EtherChannels by exchanging LACP packets between Ethernet ports.

By using LACP, the switch learns the identity of partners capable of supporting LACP and the capabilities of each port. It then dynamically groups similarly configured ports into a single logical link (channel or aggregate port). Similarly configured ports are grouped based on hardware, administrative, and port parameter constraints. For example, LACP groups the ports with the same speed, duplex mode, native VLAN, VLAN range, and trunking status and type. After grouping the links into an EtherChannel, LACP adds the group to the spanning tree as a single switch port.

LACP Modes

Table 35-2 shows the user-configurable EtherChannel LACP modes for the channel-group interface configuration command on a port.

Table 35-2 EtherChannel LACP Modes 

Mode
Description

active

Places a port into an active negotiating state in which the port starts negotiations with other ports by sending LACP packets.

passive

Places a port into a passive negotiating state in which the port responds to LACP packets that it receives, but does not start LACP packet negotiation. This setting minimizes the transmission of LACP packets.


Both the active and passive LACP modes enable ports to negotiate with partner ports to an EtherChannel based on criteria such as port speed and, for Layer 2 EtherChannels, trunking state and VLAN numbers.

Ports can form an EtherChannel when they are in different LACP modes as long as the modes are compatible. For example:

A port in the active mode can form an EtherChannel with another port that is in the active or passive mode.

A port in the passive mode cannot form an EtherChannel with another port that is also in the passive mode because neither port starts LACP negotiation.

LACP Interaction with Other Features

The CDP sends and receives packets over the physical ports in the EtherChannel. Trunk ports send and receive LACP PDUs on the lowest numbered VLAN.

In Layer 2 EtherChannels, the first port in the channel that comes up provides its MAC address to the EtherChannel. If this port is removed from the bundle, one of the remaining ports in the bundle provides its MAC address to the EtherChannel.

LACP sends and receives LACP PDUs only from ports that are up and have LACP enabled for the active or passive mode.

EtherChannel On Mode

EtherChannel on mode can be used to manually configure an EtherChannel. The on mode forces a port to join an EtherChannel without negotiations. It can be useful if the remote device does not support PAgP or LACP. With the on mode, a usable EtherChannel exists only when both ends of the link are configured in the on mode.

Ports that are configured in the on mode in the same channel group must have compatible port characteristics, such as speed and duplex. Ports that are not compatible are suspended, even though they are configured in the on mode.


Caution You should use care when using the on mode. This is a manual configuration, and ports on both ends of the EtherChannel must have the same configuration. If the group is misconfigured, packet loss or spanning-tree loops can occur.

Load Balancing and Forwarding Methods

EtherChannel balances the traffic load across the links in a channel by reducing part of the binary pattern formed from the addresses in the frame to a numerical value that selects one of the links in the channel. EtherChannel load balancing can use MAC addresses or IP addresses, source or destination addresses, or both source and destination addresses. The selected mode applies to all EtherChannels configured on the switch. You configure the load balancing and forwarding method by using the port-channel load-balance global configuration command.

With source-MAC address forwarding, when packets are forwarded to an EtherChannel, they are distributed across the ports in the channel based on the source-MAC address of the incoming packet. Therefore, to provide load balancing, packets from different hosts use different ports in the channel, but packets from the same host use the same port in the channel.

With destination-MAC address forwarding, when packets are forwarded to an EtherChannel, they are distributed across the ports in the channel based on the destination-host MAC address of the incoming packet. Therefore, packets to the same destination are forwarded over the same port, and packets to a different destination are sent on a different port in the channel.

The switch supports load distribution based on the destination host MAC address supports for only four ports per EtherChannel. When you configure EtherChannel destination-MAC address load balancing, the traffic is balanced only among four ports in the channel group.If you configure more than four ports in an EtherChannel with destination host MAC address load distribution, only four of the ports receive distributed traffic. This limitation does not apply to the other load distribution methods.

With source-and-destination MAC address forwarding, when packets are forwarded to an EtherChannel, they are distributed across the ports in the channel based on both the source and destination MAC addresses. This forwarding method, a combination source-MAC and destination-MAC address forwarding methods of load distribution, can be used if it is not clear whether source-MAC or destination-MAC address forwarding is better suited on a particular switch. With source-and-destination MAC-address forwarding, packets sent from host A to host B, host A to host C, and host C to host B could all use different ports in the channel.

With source-IP-address-based forwarding, when packets are forwarded to an EtherChannel, they are distributed across the ports in the EtherChannel based on the source-IP address of the incoming packet. Therefore, to provide load-balancing, packets from different IP addresses use different ports in the channel, but packets from the same IP address use the same port in the channel.

With destination-IP-address-based forwarding, when packets are forwarded to an EtherChannel, they are distributed across the ports in the EtherChannel based on the destination-IP address of the incoming packet. Therefore, to provide load-balancing, packets from the same IP source address sent to different IP destination addresses could be sent on different ports in the channel. But packets sent from different source IP addresses to the same destination IP address are always sent on the same port in the channel.

With source-and-destination IP address-based forwarding, when packets are forwarded to an EtherChannel, they are distributed across the ports in the EtherChannel based on both the source and destination IP addresses of the incoming packet. This forwarding method, a combination of source-IP and destination-IP address-based forwarding, can be used if it is not clear whether source-IP or destination-IP address-based forwarding is better suited on a particular switch. In this method, packets sent from the IP address A to IP address B, from IP address A to IP address C, and from IP address C to IP address B could all use different ports in the channel.

Different load-balancing methods have different advantages, and the choice of a particular load-balancing method should be based on the position of the switch in the network and the kind of traffic that needs to be load-distributed. In Figure 35-3, an EtherChannel of four workstations communicates with a router. Because the router is a single-MAC-address device, source-based forwarding on the switch EtherChannel ensures that the switch uses all available bandwidth to the router. The router is configured for destination-based forwarding because the large number of workstations ensures that the traffic is evenly distributed from the router EtherChannel.

Use the option that provides the greatest variety in your configuration. For example, if the traffic on a channel is going only to a single MAC address, using the destination-MAC address always chooses the same link in the channel. Using source addresses or IP addresses might result in better load balancing.

Figure 35-3 Load Distribution and Forwarding Methods

Configuring EtherChannels

Default EtherChannel Configuration

EtherChannel Configuration Guidelines

Configuring Layer 2 EtherChannels (required)

Configuring Layer 3 EtherChannels (required)

Configuring EtherChannel Load Balancing (optional)

Configuring the PAgP Learn Method and Priority (optional)

Configuring LACP Hot-Standby Ports (optional)

Configuring the EtherChannel Min-Links Feature (optional)

EtherChannels and Ethernet Flow Points (EFPs) (optional)


Note Make sure that the ports are correctly configured. For more information, see the "EtherChannel Configuration Guidelines" section.



Note After you configure an EtherChannel, configuration changes applied to the port-channel interface apply to all the physical ports assigned to the port-channel interface, and configuration changes applied to the physical port affect only the port to which you apply the configuration.


Default EtherChannel Configuration

Table 35-3 shows the default EtherChannel configuration.

Table 35-3 Default EtherChannel Configuration 

Feature
Default Setting

Channel groups

None assigned.

Port-channel logical interface

None defined.

PAgP mode

No default.

PAgP learn method

Aggregate-port learning.

PAgP priority

128.

LACP mode

No default.

LACP learn method

Aggregate-port learning.

LACP port priority

32768.

LACP system priority

32768.

LACP system ID

LACP system priority and the switch MAC address.

Load balancing

Load distribution on the switch is based on the source-MAC address of the incoming packet.


EtherChannel Configuration Guidelines

If improperly configured, some EtherChannel ports are automatically disabled to avoid network loops and other problems. Follow these guidelines to avoid configuration problems:

Do not try to configure more than 26 EtherChannels on the switch.

Configure all ports in an EtherChannel to operate at the same speeds and duplex modes.

Enable all ports in an EtherChannel. A port in an EtherChannel that is disabled by using the shutdown interface configuration command is treated as a link failure, and its traffic is transferred to one of the remaining ports in the EtherChannel. ME 3800X and ME 3600X ports are enabled by default.

When a group is first created, all ports follow the parameters set for the first port to be added to the group. If you change the configuration of one of these parameters, you must also make the changes to all ports in the group:

Allowed-VLAN list

Spanning-tree path cost for each VLAN

Spanning-tree port priority for each VLAN

Spanning-tree Port Fast setting

Do not configure a port to be a member of more than one EtherChannel group.

Do not configure an EtherChannel in both the PAgP and LACP modes. EtherChannel groups running PAgP and LACP can coexist on the same switch. Individual EtherChannel groups can run either PAgP or LACP, but they cannot interoperate.

For Layer 2 EtherChannels:

Assign all ports in the EtherChannel to the same VLAN, or configure them as trunks. Ports with different native VLANs cannot form an EtherChannel.

You cannot assign a port configured with a service instance to an EtherChannel.

If you configure an EtherChannel from trunk ports, verify that the trunking mode is the same on all the trunks. Inconsistent trunk modes on EtherChannel ports can have unexpected results.

An EtherChannel supports the same allowed range of VLANs on all the ports in a trunking Layer 2 EtherChannel. If the allowed range of VLANs is not the same, the ports do not form an EtherChannel even when PAgP is set to the auto or desirable mode.

Ports with different spanning-tree path costs can form an EtherChannel if they are otherwise compatibly configured. Setting different spanning-tree path costs does not, by itself, make ports incompatible for the formation of an EtherChannel.

For Layer 3 EtherChannels, assign the Layer 3 address to the port-channel logical interface, not to the physical ports in the channel.

For configuring Ethernet Virtual Connections (EVCs), you can add a service instance to an EtherChannel port channel.

Configuring Layer 2 EtherChannels

You configure Layer 2 EtherChannels by assigning ports to a channel group with the channel-group interface configuration command. This command automatically creates the port-channel logical interface.


Note Although you cannot assign a port configured with an EFP service instance to an EtherChannel, you can configure service instances on EtherChannel port channels.


Beginning in privileged EXEC mode, follow these steps to assign a Layer 2 Ethernet port to a Layer 2 EtherChannel. This procedure is required.

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface interface-id

Specify a physical port, and enter interface configuration mode.

For a PAgP EtherChannel, you can configure up to eight ports of the same type and speed for the same group.

For a LACP EtherChannel, you can configure up to 16 Ethernet ports of the same type. Up to eight ports can be active, and up to eight ports can be in standby mode.

Note An EtherChannel port cannot be a port configured with a service instance.

Step 3 

switchport mode {access | trunk}switchport access vlan vlan-id

Assign all ports as static-access ports in the same VLAN, or configure them as trunks.

If you configure the port as a static-access port, assign it to only one VLAN. The range is 1 to 4094.

Step 4 

channel-group channel-group-number mode {auto [non-silent] | desirable [non-silent] | on} | {active | passive}

Assign the port to a channel group, and specify the PAgP or the LACP mode.

For channel-group-number, the range is 1 to 26.

For mode, select one of these keywords:

autoEnables PAgP only if a PAgP device is detected. It places the port into a passive negotiating state, in which the port responds to PAgP packets it receives but does not start PAgP packet negotiation.

desirable—Unconditionally enables PAgP. It places the port into an active negotiating state, in which the port starts negotiations with other ports by sending PAgP packets.

onForces the port to channel without PAgP or LACP. With the on mode, a usable EtherChannel exists only when a port group in the on mode is connected to another port group in the on mode.

non-silent—(Optional) If your switch is connected to a partner that is PAgP-capable, configure the switch port for nonsilent operation when the port is in the auto or desirable mode. If you do not specify non-silent, silent is assumed. The silent setting is for connections to file servers or packet analyzers. This setting allows PAgP to operate, to attach the port to a channel group, and to use the port for transmission.

activeEnables LACP only if a LACP device is detected. It places the port into an active negotiating state in which the port starts negotiations with other ports by sending LACP packets.

passiveEnables LACP on the port and places it into a passive negotiating state in which the port responds to LACP packets that it receives, but does not start LACP packet negotiation.

For information on compatible modes for the switch and its partner, see the "PAgP Modes" section and the "LACP Modes" section.

Step 5 

end

Return to privileged EXEC mode.

Step 6 

show running-config

Verify your entries.

Step 7 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To remove a port from the EtherChannel group, use the no channel-group interface configuration command.

This example shows how to configure an EtherChannel. It assigns two ports as static-access ports in VLAN 10 to channel 5 with the PAgP mode desirable:

Switch# configure terminal 
Switch(config)# interface range gigabitethernet0/1 -2 
Switch(config-if-range)# switchport mode access
Switch(config-if-range)# switchport access vlan 10
Switch(config-if-range)# channel-group 5 mode desirable non-silent
Switch(config-if-range)# end 
 
   

This example shows how to configure an EtherChannel. It assigns two ports as static-access ports in VLAN 10 to channel 5 with the LACP mode active:

Switch# configure terminal 
Switch(config)# interface range gigabitethernet0/1 -2 
Switch(config-if-range)# switchport mode access
Switch(config-if-range)# switchport access vlan 10
Switch(config-if-range)# channel-group 5 mode active
Switch(config-if-range)# end 

Configuring Layer 3 EtherChannels

To configure Layer 3 EtherChannels, you create the port-channel logical interface and then put the Ethernet ports into the port-channel as described in the next two sections.

Creating Port-Channel Logical Interfaces

When configuring Layer 3 EtherChannels, you should first manually create the port-channel logical interface by using the interface port-channel global configuration command. Then you put the logical interface into the channel group by using the channel-group interface configuration command.


Note To move an IP address from a physical port to an EtherChannel, you must delete the IP address from the physical port before configuring it on the port-channel interface.


Beginning in privileged EXEC mode, follow these steps to create a port-channel interface for a Layer 3 EtherChannel. This procedure is required.

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface port-channel port-channel-number

Specify the port-channel logical interface, and enter interface configuration mode.

For port-channel-number, the range is 1 to 26.

Step 3 

ip address ip-address mask

Assign an IP address and subnet mask to the EtherChannel.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show etherchannel channel-group-number detail

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

Step 7 

 

Assign an Ethernet port to the Layer 3 EtherChannel. For more information, see the "Configuring the Physical Interfaces" section.

To remove the port-channel, use the no interface port-channel port-channel-number global configuration command.

This example shows how to create the logical port channel 5 and assign 172.10.20.10 as its IP address:

Switch# configure terminal 
Switch(config)# interface port-channel 5
Switch(config-if)# no switchport
Switch(config-if)# ip address 172.10.20.10 255.255.255.0
Switch(config-if)# end 

Configuring the Physical Interfaces

Beginning in privileged EXEC mode, follow these steps to assign an Ethernet port to a Layer 3 EtherChannel. This procedure is required.

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface interface-id

Specify a physical port, and enter interface configuration mode.

Valid interfaces include physical ports.

For a PAgP EtherChannel, you can configure up to eight ports of the same type and speed for the same group.

For a LACP EtherChannel, you can configure up to 16 Ethernet ports of the same type. Up to eight ports can be active, and up to eight ports can be in standby mode.

Step 3 

no ip address

Ensure that there is no IP address assigned to the physical port.

Step 4 

no switchport

Put the port into Layer 3 mode.

Step 5 

channel-group channel-group-number mode {auto [non-silent] | desirable [non-silent] | on} | {active | passive}

Assign the port to a channel group, and specify the PAgP or the LACP mode.

For channel-group-number, the range is 1 to 26. This number must be the same as the port-channel-number (logical port) configured in the "Creating Port-Channel Logical Interfaces" section.

For mode, select one of these keywords:

auto—Enables PAgP only if a PAgP device is detected. It places the port into a passive negotiating state, in which the port responds to PAgP packets it receives but does not start PAgP packet negotiation.

desirable—Unconditionally enables PAgP. It places the port into an active negotiating state, in which the port starts negotiations with other ports by sending PAgP packets.

on—Forces the port to channel without PAgP or LACP. With the on mode, a usable EtherChannel exists only when a port group in the on mode is connected to another port group in the on mode.

non-silent—(Optional) If your switch is connected to a partner that is PAgP capable, configure the switch port for nonsilent operation when the port is in the auto or desirable mode. If you do not specify non-silent, silent is assumed. The silent setting is for connections to file servers or packet analyzers. This setting allows PAgP to operate, to attach the port to a channel group, and to use the port for transmission.

activeEnables LACP only if a LACP device is detected. It places the port into an active negotiating state in which the port starts negotiations with other ports by sending LACP packets.

passiveEnables LACP on the port and places it into a passive negotiating state in which the port responds to LACP packets that it receives, but does not start LACP packet negotiation.

For information on compatible modes for the switch and its partner, see the "PAgP Modes" section and the "LACP Modes" section.

Step 6 

end

Return to privileged EXEC mode.

Step 7 

show running-config

Verify your entries.

Step 8 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

This example shows how to configure an EtherChannel. It assigns two ports to channel 5 with the LACP mode active:

Switch# configure terminal 
Switch(config)# interface range gigabitethernet0/1 -2 
Switch(config-if-range)# no ip address 
Switch(config-if-range)# no switchport
Switch(config-if-range)# channel-group 5 mode active
Switch(config-if-range)# end

Configuring EtherChannel Load Balancing

This section describes how to configure EtherChannel load balancing by using source-based or destination-based forwarding methods. For more information, see the "Load Balancing and Forwarding Methods" section.

Beginning in privileged EXEC mode, follow these steps to configure EtherChannel load balancing. This procedure is optional.

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

port-channel load-balance {dst-ip | dst-mac | src-dst-ip | src-dst-mac | src-ip | src-mac}

Configure an EtherChannel load-balancing method.

The default is src-mac.

Select one of these load-distribution methods:

dst-ip—Load distribution is based on the destination-host IP address.

dst-mac—Load distribution is based on the destination-host MAC address of the incoming packet.

src-dst-ip—Load distribution is based on the source-and-destination host-IP address.

src-dst-mac—Load distribution is based on the source-and-destination host-MAC address.

src-ip—Load distribution is based on the source-host IP address.

src-mac—Load distribution is based on the source-MAC address of the incoming packet.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show etherchannel load-balance

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To return EtherChannel load balancing to the default configuration, use the no port-channel load-balance global configuration command.

Configuring the PAgP Learn Method and Priority

Network devices are classified as PAgP physical learners or aggregate-port learners. A device is a physical learner if it learns addresses by physical ports and directs transmissions based on that knowledge. A device is an aggregate-port learner if it learns addresses by aggregate (logical) ports. The learn method must be configured the same at both ends of the link.

When a device and its partner are both aggregate-port learners, they learn the address on the logical port-channel. The device sends packets to the source by using any of the ports in the EtherChannel. With aggregate-port learning, it is not important on which physical port the packet arrives.

PAgP cannot automatically detect when the partner device is a physical learner and when the local device is an aggregate-port learner. Therefore, you must manually set the learning method on the local device to learn addresses by physical ports. You also must set the load-distribution method to source-based distribution, so that any given source MAC address is always sent on the same physical port.

You also can configure a single port within the group for all transmissions and use other ports for hot standby. The unused ports in the group can be swapped into operation in just a few seconds if the selected single port loses hardware-signal detection. You can configure which port is always selected for packet transmission by changing its priority with the pagp port-priority interface configuration command. The higher the priority, the more likely that the port will be selected.


Note The switch supports address learning only on aggregate ports even though the physical-port keyword is provided in the CLI. The pagp learn-method command and the pagp port-priority command have no effect on the switch hardware, but they are required for PAgP interoperability with devices that only support address learning by physical ports.

When the link partner to the switch is a physical learner, we recommend that you configure the Cisco ME switch as a physical-port learner by using the pagp learn-method physical-port interface configuration command. Set the load-distribution method based on the source MAC address by using the port-channel load-balance src-mac global configuration command. The switch then sends packets to the physical learner switch using the same port in the EtherChannel from which it learned the source address. Use the pagp learn-method command only in this situation.


Beginning in privileged EXEC mode, follow these steps to configure your switch as a PAgP physical-port learner and to adjust the priority so that the same port in the bundle is selected for sending packets. This procedure is optional.

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface interface-id

Specify the port for transmission, and enter interface configuration mode.

Step 3 

pagp learn-method physical-port

Select the PAgP learning method.

By default, aggregation-port learning is selected, which means the switch sends packets to the source by using any of the ports in the EtherChannel. With aggregate-port learning, it is not important on which physical port the packet arrives.

Select physical-port to connect with another switch that is a physical learner. Make sure to configure the port-channel load-balance global configuration command to src-mac as described in the "Configuring EtherChannel Load Balancing" section.

The learning method must be configured the same at both ends of the link.

Step 4 

pagp port-priority priority

Assign a priority so that the selected port is chosen for packet transmission.

For priority, the range is 0 to 255. The default is 128. The higher the priority, the more likely that the port will be used for PAgP transmission.

Step 5 

end

Return to privileged EXEC mode.

Step 6 

show running-config

or

show pagp channel-group-number internal

Verify your entries.

Step 7 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To return the priority to its default setting, use the no pagp port-priority interface configuration command. To return the learning method to its default setting, use the no pagp learn-method interface configuration command.

Configuring LACP Hot-Standby Ports

When enabled, LACP tries to configure the maximum number of LACP-compatible ports in a channel, up to a maximum of 16 ports. Only eight LACP links can be active at one time. The software places any additional links in a hot-standby mode. If one of the active links becomes inactive, a link that is in the hot-standby mode becomes active in its place.

If you configure more than eight links for an EtherChannel group, the software automatically decides which of the hot-standby ports to make active based on the LACP priority. The software assigns to every link between systems that operate LACP a unique priority made up of these elements (in priority order):

LACP system priority

System ID (a combination of the LACP system priority and the switch MAC address)

LACP port priority

Port number

In priority comparisons, numerically lower values have higher priority. The priority decides which ports should be put in standby mode when there is a hardware limitation that prevents all compatible ports from aggregating.

Ports are considered for active use in aggregation in link-priority order starting with the port attached to the highest priority link. Each port is selected for active use if the preceding higher priority selections can also be maintained. Otherwise, the port is selected for standby mode.

You can change the default values of the LACP system priority and the LACP port priority to affect how the software selects active and standby links. For more information, see the "Configuring the LACP System Priority" section and the "Configuring the LACP Port Priority" section.

Configuring the LACP System Priority

You can configure the system priority for all of the EtherChannels that are enabled for LACP by using the lacp system-priority global configuration command. You cannot configure a system priority for each LACP-configured channel. By changing this value from the default, you can affect how the software selects active and standby links.

You can use the show etherchannel summary privileged EXEC command to see which ports are in the hot-standby mode (denoted with an H port-state flag).

Beginning in privileged EXEC mode, follow these steps to configure the LACP system priority. This procedure is optional.

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

lacp system-priority priority

Configure the LACP system priority.

For priority, the range is 1 to 65535. The default is 32768.

The lower the value, the higher the system priority.

Step 3 

end

Return to privileged EXEC mode.

Step 4 

show running-config

or

show lacp sys-id

Verify your entries.

Step 5 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To return the LACP system priority to the default value, use the no lacp system-priority global configuration command.

Configuring the LACP Port Priority

By default, all ports use the same port priority. If the local system has a lower value for the system priority and the system ID than the remote system, you can affect which of the hot-standby links become active first by changing the port priority of LACP EtherChannel ports to a lower value than the default. The hot-standby ports that have lower port numbers become active in the channel first. You can use the show etherchannel summary privileged EXEC command to see which ports are in the hot-standby mode (denoted with an H port-state flag).


Note If LACP is not able to aggregate all the ports that are compatible (for example, the remote system might have more restrictive hardware limitations), all the ports that cannot be actively included in the EtherChannel are put in the hot-standby state and are used only if one of the channeled ports fails.


Beginning in privileged EXEC mode, follow these steps to configure the LACP port priority. This procedure is optional.

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface interface-id

Specify the port to be configured, and enter interface configuration mode.

Step 3 

lacp port-priority priority

Configure the LACP port priority.

For priority, the range is 1 to 65535. The default is 32768. The lower the value, the more likely that the port will be used for LACP transmission.

Step 4 

end

Return to privileged EXEC mode.

Step 5 

show running-config

or

show lacp [channel-group-number] internal

Verify your entries.

Step 6 

copy running-config startup-config

(Optional) Save your entries in the configuration file.

To return the LACP port priority to the default value, use the no lacp port-priority interface configuration command.

Configuring the EtherChannel Min-Links Feature

The EtherChannel min-links feature is supported on LACP EtherChannels. This feature allows you to configure the minimum number of member ports that must be in the link-up state and bundled in the EtherChannel for the port channel interface to transition to the link-up state. You can use the EtherChannel min-links feature to prevent low-bandwidth LACP EtherChannels from becoming active. This feature also causes LACP EtherChannels to become inactive if they have too few active member ports to supply your required minimum bandwidth. In addition, when LACP max-bundle values are specified in conjunction with min-links, the configuration is verified and an error message is returned if the min-links value is not compatible with (equal to or less than) the max-bundle value.

To configure the EtherChannel min-links feature, perform this task:

 
Command
Purpose

Step 1 

configure terminal

Enter global configuration mode.

Step 2 

interface port-channel group_number

Selects an LACP port channel interface.

Step 3 

port-channel min-links number

Configures the minimum number of member ports that must be in the link-up state and bundled in the EtherChannel for the port channel interface to transition to the link-up state.

A minimum of 2 active links must be bundled together under a port channel to activate the min-link feature.

Step 4 

end

Exits configuration mode.

Step 5 

show running-config interface port-channel group_number

show interfaces type1 slot/port etherchannel

Verifies the configuration.

Step 6 

show etherchannel port-channel interface detail

Displays the usage of min-link on the portchannel. Displays additional information

1 type = fastethernet, gigabitethernet, or tengigabitethernet

Use the no port-channel min-links number command to restore default etherchannel min-links configuration.

Where a bundle fails to meet the criteria for min-link configuration an error message is displayed. Use the show etherchannel port-channel interface detail command to display additional information not provided in the error message to determine the reason for the failure.


Note Although the EtherChannel min-links feature works correctly when configured only on one end of an EtherChannel, for best results, configure the same number of minimum links on both ends of the EtherChannel.


This example shows how to configure port channel interface 1 to be inactive if fewer than two member ports are active in the EtherChannel:

Switch# configure terminal 
Switch(config)# interface port-channel 1 
Switch(config-if)# port-channel min-links 2 
Switch(config-if)# end 

This example shows the output from the show etherchannel port-channel interface detail command:

Switch#show etherchannel 10 detail 
Group state = L2 
Ports: 3 Maxports = 16
Port-channels: 1 Max Port-channels = 16
Protocol: LACP
Minimum Links: 3
Ports in the group:
-------------------
Port: Gi0/12
------------
 
   
Port state = Up Mstr In-Bndl 
Channel group = 10 Mode = Active Gcchange = -
Port-channel = Po10 GC = - Pseudo port-channel = Po10
Port index = 0 Load = 0x00 Protocol = LACP
Mode = LACP
 
   
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
 
   
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Gi0/12 SA bndl 32768 0xA 0xA 0x10D 0x3D 
 
   
Partner's information:
 
   
Partner Partner LACP Partner Partner Partner Partner Partner
Port Flags State Port Priority Admin Key Oper Key Port Number Port State
Gi0/12 SA bndl 32768 0x0 0xA 0x114 0x3D 
 
   
Age of the port in the current state: 1d:00h:24m:51s
 
   
Port: Gi0/13
------------
 
   
Port state = Up Mstr In-Bndl 
Channel group = 10 Mode = Active Gcchange = -
Port-channel = Po10 GC = - Pseudo port-channel = Po10
Port index = 0 Load = 0x00 Protocol = LACP
Mode = LACP
 
   
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
 
   
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Gi0/13 SA bndl 32768 0xA 0xA 0x10E 0x3D 
 
   
Partner's information:
 
   
Partner Partner LACP Partner Partner Partner Partner Partner
Port Flags State Port Priority Admin Key Oper Key Port Number Port State
Gi0/13 SA bndl 32768 0x0 0xA 0x104 0x3D 
 
   
Age of the port in the current state: 1d:00h:24m:48s
 
   
Port: Gi0/20
------------
 
   
Port state = Up Mstr In-Bndl 
Channel group = 10 Mode = Active Gcchange = -
Port-channel = Po10 GC = - Pseudo port-channel = Po10
Port index = 0 Load = 0x00 Protocol = LACP
Mode = LACP
 
   
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
 
   
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Gi0/20 SA bndl 32768 0xA 0xA 0x115 0x3D 
 
   
Partner's information:
 
   
Partner Partner LACP Partner Partner Partner Partner Partner
Port Flags State Port Priority Admin Key Oper Key Port Number Port State
Gi0/20 SA bndl 32768 0x0 0xA 0x115 0x3D 
 
   
Age of the port in the current state: 1d:00h:24m:43s
 
   
Port-channels in the group: 
----------------------
 
   
Port-channel: Po10 (Primary Aggregator)
 
   
------------
 
   
Age of the Port-channel = 1d:00h:36m:54s
Logical slot/port = 2/10 Number of ports = 3
HotStandBy port = null 
Port state = Port-channel Ag-Inuse 
Protocol = LACP
Fast-switchover = disabled
Direct Load Swap = disabled
 
   
Ports in the Port-channel: 
 
   
Index Load Port EC state No of bits
------+------+--------+------------------+-----------
0 00 Gi0/12 Active 0
0 00 Gi0/13 Active 0
0 00 Gi0/20 Active 0
 
   
Time since last port bundled: 1d:00h:24m:43s Gi0/20
Time since last port Un-bundled: 1d:00h:24m:45s Gi0/20
 
   
Last applied Hash Distribution Algorithm: -
Channel-group Iedge Counts: 
--------------------------: 
Access ref count : 0
Iedge session count : 0
 
   
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
   
Switch#
009215: 1d00h: %EC-5-MINLINKS_NOTMET: Port-channel Po10 is down bundled ports (2) doesn't 
meet min-links <<<<<<<<<<< Error messsage thrown on member
009216: 1d00h: %LINK-3-UPDOWN: Interface Port-channel10, changed state to down Link 
Failure
009217: 1d00h: %LINK-3-UPDOWN: Interface GigabitEthernet0/20, changed state to down
009218: 1d00h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/20, 
changed state to down
009219: 1d00h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/12, 
changed state to down
009220: 1d00h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/13, 
changed state to down
009221: 1d00h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel10, changed 
state to down
 
   
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 
   
 
   
Switch#show etherchannel 10 detail 
Group state = L2 
Ports: 3 Maxports = 16
Port-channels: 1 Max Port-channels = 16
Protocol: LACP
Minimum Links: 3
Ports in the group:
-------------------
Port: Gi0/12
------------
 
   
Port state = Up Mstr In-Bndl 
Channel group = 10 Mode = Active Gcchange = -
Port-channel = Po10 GC = - Pseudo port-channel = Po10
Port index = 0 Load = 0x00 Protocol = LACP
Mode = LACP
 
   
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
 
   
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Gi0/12 SA bndl 32768 0xA 0xA 0x10D 0x3D 
 
   
Partner's information:
 
   
Partner Partner LACP Partner Partner Partner Partner Partner
Port Flags State Port Priority Admin Key Oper Key Port Number Port State
Gi0/12 SA bndl 32768 0x0 0xA 0x114 0x3D 
 
   
Age of the port in the current state: 1d:00h:26m:00s
 
   
Port: Gi0/13
------------
 
   
Port state = Up Mstr In-Bndl 
Channel group = 10 Mode = Active Gcchange = -
Port-channel = Po10 GC = - Pseudo port-channel = Po10
Port index = 0 Load = 0x00 Protocol = LACP
Mode = LACP
 
   
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
 
   
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Gi0/13 FA bndl 32768 0xA 0xA 0x10E 0x3D 
 
   
Partner's information:
 
   
Partner Partner LACP Partner Partner Partner Partner Partner
Port Flags State Port Priority Admin Key Oper Key Port Number Port State
Gi0/13 SA bndl 32768 0x0 0xA 0x104 0xF 
 
   
Age of the port in the current state: 1d:00h:25m:57s
 
   
Port: Gi0/20
------------
 
   
Port state = Down Not-in-Bndl 
Channel group = 10 Mode = Active Gcchange = -
Port-channel = null GC = - Pseudo port-channel = Po10
Port index = 0 Load = 0x00 Protocol = LACP
Mode = Unknown
 
   
Flags: S - Device is sending Slow LACPDUs F - Device is sending fast LACPDUs.
A - Device is in active mode. P - Device is in passive mode.
 
   
Local information:
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Gi0/20 SA down 32768 0xA 0xA 0x115 0x7 
 
   
Partner's information:
 
   
Partner Partner LACP Partner Partner Partner Partner Partner
Port Flags State Port Priority Admin Key Oper Key Port Number Port State
Gi0/20 FP down 32768 0x0 0xA 0x115 0x34 
 
   
Age of the port in the current state: 1d:00h:25m:51s
 
   
Port-channels in the group: 
----------------------
 
   
Port-channel: Po10 (Primary Aggregator)
 
   
------------
 
   
Age of the Port-channel = 1d:00h:38m:03s
Logical slot/port = 2/10 Number of ports = 2
HotStandBy port = null 
Port state = Port-channel Ag-MinLink-Not-Inuse <<<<<<<<<<<<<< Reason as to why the link is 
down
Protocol = LACP
Fast-switchover = disabled
Direct Load Swap = disabled
 
   
Ports in the Port-channel: 
 
   
Index Load Port EC state No of bits
------+------+--------+------------------+-----------
0 00 Gi0/12 Active 0
0 00 Gi0/13 Active 0
 
   
Time since last port bundled: 1d:00h:25m:51s Gi0/20
Time since last port Un-bundled: 0d:00h:00m:10s Gi0/20
 
   
Last applied Hash Distribution Algorithm: -
Channel-group Iedge Counts: 
--------------------------: 
Access ref count : 0
Iedge session count : 0
 
   

EtherChannels and Ethernet Flow Points (EFPs)

For an LACP or PAgP port to peer with a neighbor on a port that has an Ethernet Virtual Connection (EVC) EFP service instance configured, you need to enter the l2 protocol peer lacp or l2 protocol peer lacp service-instance configuration command on the service instance. See the "Configuring Ethernet Virtual Connections (EVCs)" chapter for more information on EFPs.

This example shows how to configure Layer 2 protocol LACP peer on a service instance:

Switch (config)# interface gigabitethernet0/1
Switch (config-if)# switchport mode trunk
Switch (config-if)# switchport trunk allowed vlan none
Switch (config-if)# service instance 1 Ethernet 
Switch (config-if-srv)# encapsulation untagged
Switch (config-if-srv)# l2protocol peer lacp
Switch (config-if-srv)# bridge-domain 10
Switch (config-if-srv)# end

Displaying EtherChannel, PAgP, and LACP Status

To display EtherChannel, PAgP, and LACP status information, use the privileged EXEC commands described in Table 35-4:

Table 35-4 Commands for Displaying EtherChannel, PAgP, and LACP Status 

Command
Description

show etherchannel [channel-group-number {detail | port | port-channel | protocol | summary}] {detail | load-balance | port | port-channel | protocol | summary}

Displays EtherChannel information in a brief, detailed, and one-line summary form. Also displays the load-balance or frame-distribution scheme, port, port-channel, and protocol information.

show pagp [channel-group-number] {counters | internal | neighbor}

Displays PAgP information such as traffic information, the internal PAgP configuration, and neighbor information.

show lacp [channel-group-number] {counters | internal | neighbor}

Displays LACP information such as traffic information, the internal LACP configuration, and neighbor information.


You can clear PAgP channel-group information and traffic counters by using the clear pagp {channel-group-number counters | counters} privileged EXEC command.

You can clear LACP channel-group information and traffic counters by using the clear lacp {channel-group-number counters | counters} privileged EXEC command.

For detailed information about the fields in the displays, see the command reference for this release.