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All ports in an EtherChannel must be assigned to the same VLAN or they must be configured as trunk ports.
When the ports in an EtherChannel are configured as trunk ports, all the ports must be configured with the same mode (either Inter-Switch Link [ISL] or IEEE 802.1Q).
This section provides information about EtherChannels
EtherChannel provides fault-tolerant high-speed links between switches, routers, and servers. You can use the EtherChannel 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.
An EtherChannel consists of individual Ethernet links bundled into a single logical link.
The number of EtherChannels is limited to 6.
Each EtherChannel can consist of up to eight compatibly configured Ethernet ports.
An EtherChannel comprises a channel group and a port-channel interface. The channel group binds physical ports to the port-channel interface. Configuration changes applied to the port-channel interface apply to all the physical ports bound together in the channel group.
The channel-group command binds the physical port and the port-channel interface together. Each EtherChannel has a port-channel logical interface numbered from 1 to 6 . This port-channel interface number corresponds to the one specified with the channel-group interface configuration command.
With Layer 2 ports, use the channel-group interface configuration command to dynamically create the port-channel interface.
You also can use the interface port-channel port-channel-number global configuration command to manually create the port-channel 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.
The Port Aggregation Protocol (PAgP) is a Cisco-proprietary protocol that can be run only on Cisco devices and on those devices 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 (on a single switch) 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 specify whether a port can send PAgP packets, which start PAgP negotiations, or only respond to PAgP packets received.
|
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, based on trunk 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 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.
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, such as the Catalyst 1900 switch. |
A virtual switch can be two or more core switches connected by virtual switch links (VSLs) that carry control and data traffic between them. One of the switches is in active mode. The others are in standby mode. For redundancy, remote switches are connected to the virtual switch by remote satellite links (RSLs).
If the VSL between two switches fails, one switch does not know the status of the other. Both switches could change to the active mode, causing a dual-active situation in the network with duplicate configurations (including duplicate IP addresses and bridge identifiers). The network might go down.
To prevent a dual-active situation, the core switches send PAgP protocol data units (PDUs) through the RSLs to the remote switches. The PAgP PDUs identify the active switch, and the remote switches forward the PDUs to core switches so that the core switches are in sync. If the active switch fails or resets, the standby switch takes over as the active switch. If the VSL goes down, one core switch knows the status of the other and does not change its state.
The Dynamic Trunking Protocol (DTP) and the Cisco Discovery Protocol (CDP) send and receive 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.
The LACP is defined in IEEE 802.3ad and enables Cisco devices to manage Ethernet channels between devices that conform to the IEEE 802.3ad protocol. 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.
The independent mode behavior of ports in a port channel is changed. With CSCtn96950, by default, standalone mode is enabled. When no response is received from an LACP peer, ports in the port channel are moved to suspended state.
LACP modes specify whether a port can send LACP packets or only receive LACP packets.
|
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, based on trunk 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.
The DTP and the CDP send and receive 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 can be used to manually configure an EtherChannel. The on mode forces a port to join an EtherChannel without negotiations. The on mode can be useful if the remote device does not support PAgP or LACP. In the on mode, a usable EtherChannel exists only when the device at 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. |
The default EtherChannel configuration is described in this table.
|
Feature |
Default Setting |
|---|---|
|
Channel groups |
None assigned. |
|
Port-channel logical interface |
None defined. |
|
PAgP mode |
No default. |
|
PAgP learn method |
Aggregate-port learning on all ports. |
|
PAgP priority |
128 on all ports. |
|
LACP mode |
No default. |
|
LACP learn method |
Aggregate-port learning on all ports. |
|
LACP port priority |
32768 on all ports. |
|
LACP system priority |
32768. |
|
LACP system ID |
LACP system priority and the device MAC address. |
If improperly configured, some EtherChannel ports are automatically disabled to avoid network loops and other problems. Follow these guidelines to avoid configuration problems:
Configure a PAgP EtherChannel with up to eight Ethernet ports of the same type.
Configure a LACP EtherChannel with 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.
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.
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 device. Individual EtherChannel groups can run either PAgP or LACP, but they cannot interoperate.
Do not configure a secure port as part of an EtherChannel or the reverse.
Do not configure a port that is an active or a not-yet-active member of an EtherChannel as an IEEE 802.1x port. If you try to enable IEEE 802.1x on an EtherChannel port, an error message appears, and IEEE 802.1x is not enabled.
If EtherChannels are configured on device interfaces, remove the EtherChannel configuration from the interfaces before globally enabling IEEE 802.1x on a device by using the dot1x system-auth-control global configuration command.
Do not enable link-state tracking on individual interfaces that will be part of a downstream Etherchannel interface.
When configuring Layer 2 EtherChannels, follow these guidelines:
Assign all ports in the EtherChannel to the same VLAN, or configure them as trunks. Ports with different native VLANs cannot form an EtherChannel.
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.
The auto-LAG feature provides the ability to auto create EtherChannels on ports connected to a switch. By default, auto-LAG is disabled globally and is enabled on all port interfaces. The auto-LAG applies to a switch only when it is enabled globally.
On enabling auto-LAG globally, the following scenarios are possible:
All port interfaces participate in creation of auto EtherChannels provided the partner port interfaces have EtherChannel configured on them. For more information, see the "The supported auto-LAG configurations between the actor and partner devices" table below.
Ports that are already part of manual EtherChannels cannot participate in creation of auto EtherChannels.
When auto-LAG is disabled on a port interface that is already a part of an auto created EtherChannel, the port interface will unbundle from the auto EtherChannel.
The following table shows the supported auto-LAG configurations between the actor and partner devices:
|
Actor/Partner |
Active |
Passive |
Auto |
|
Active |
Yes |
Yes |
Yes |
|
Passive |
Yes |
No |
Yes |
|
Auto |
Yes |
Yes |
Yes |
On disabling auto-LAG globally, all auto created Etherchannels become manual EtherChannels.
You cannot add any configurations in an existing auto created EtherChannel. To add, you should first convert it into a manual EtherChannel by executing the port-channel<channel-number>persistent .
Note |
Auto-LAG uses the LACP protocol to create auto EtherChannel. Only one EtherChannel can be automatically created with the unique partner devices. |
Follow these guidelines when configuring the auto-LAG feature.
When auto-LAG is enabled globally and on the port interface , and if you do not want the port interface to become a member of the auto EtherChannel, disable the auto-LAG on the port interface.
A port interface will not bundle to an auto EtherChannel when it is already a member of a manual EtherChannel. To allow it to bundle with the auto EtherChannel, first unbundle the manual EtherChannel on the port interface.
When auto-LAG is enabled and auto EtherChannel is created, you can create multiple EtherChannels manually with the same partner device. But by default, the port tries to create auto EtherChannel with the partner device.
The auto-LAG is supported only on Layer 2 EtherChannel. It is not supported on Layer 3 interface and Layer 3 EtherChannel.
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 where you apply the configuration.
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.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
configure terminal Example: |
Enters global configuration mode. |
| Step 2 |
interface interface-id Example: |
Specifies a physical port, and enters interface configuration mode. Valid interfaces are 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 |
switchport mode {access | trunk} Example: |
Assigns 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 |
switchport access vlan vlan-id Example: |
(Optional) If you configure the port as a static-access port, assign it to only one VLAN. The range is 1 to 4094. |
| Step 5 |
channel-group channel-group-number mode {auto [non-silent] | desirable [non-silent ] | on } | { active | passive} Example: |
Assigns the port to a channel group, and specifies the PAgP or the LACP mode. For channel-group-number , the range is 1 to 6. For mode , select one of these keywords:
|
| Step 6 |
end Example: |
Returns to privileged EXEC mode. |
This task is optional.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
configure terminal Example: |
Enters global configuration mode. |
| Step 2 |
interface interface-id Example: |
Specifies the port for transmission, and enters interface configuration mode. |
| Step 3 |
pagp learn-method physical-port Example: |
Selects the PAgP learning method. By default, aggregation-port learning is selected, which means 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. Selects physical-port to connect with another device that is a physical learner. The learning method must be configured the same at both ends of the link. |
| Step 4 |
pagp port-priority priority Example: |
Assigns 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 Example: |
Returns to privileged EXEC mode. |
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. To every link between systems that operate LACP, the software assigns a unique priority made up of these elements (in priority order):
LACP system priority
System ID (the device 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.
Determining which ports are active and which are hot standby is a two-step procedure. First the system with a numerically lower system priority and system ID is placed in charge of the decision. Next, that system decides which ports are active and which are hot standby, based on its values for port priority and port number. The port priority and port number values for the other system are not used.
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.
You can configure the system priority for all 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).
Follow these steps to configure the LACP system priority. This procedure is optional.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
| Step 3 |
lacp system-priority priority Example: |
Configures the LACP system priority. The range is 1 to 65535. The default is 32768. The lower the value, the higher the system priority. |
| Step 4 |
end Example: |
Returns to privileged EXEC mode. |
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. |
Follow these steps to configure the LACP port priority. This procedure is optional.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
| Step 3 |
interface interface-id Example: |
Specifies the port to be configured, and enters interface configuration mode. |
| Step 4 |
lacp port-priority priority Example: |
Configures the LACP port 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 5 |
end Example: |
Returns to privileged EXEC mode. |
You can specify the minimum number of active ports that must be in the link-up state and bundled in an EtherChannel for the port channel interface to transition to the link-up state. Using EtherChannel min-links, you can prevent low-bandwidth LACP EtherChannels from becoming active. Port channel min-links also cause LACP EtherChannels to become inactive if they have too few active member ports to supply the requiredminimum bandwidth.
To configure the minimum number of links that are required for a port channel. Perform the following tasks.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
| Step 3 |
interface port-channel channel-number Example: |
Enters interface configuration mode for a port-channel. For channel-number, the range is 1 to 6. |
| Step 4 |
port-channel min-links min-links-number Example: |
Specifies 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. For min-links-number , the range is 2 to 8. |
| Step 5 |
end Example: |
Returns to privileged EXEC mode. |
You can change the LACP timer rate to modify the duration of the LACP timeout. Use the lacp rate command to set the rate at which LACP control packets are received by an LACP-supported interface. You can change the timeout rate from the default rate (30 seconds) to the fast rate (1 second). This command is supported only on LACP-enabled interfaces.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
| Step 3 |
interface { fastethernet | gigabitethernet | tengigabitethernet} slot/port Example: |
Configures an interface and enters interface configuration mode. |
| Step 4 |
lacp rate { normal | fast} Example: |
Configures the rate at which LACP control packets are received by an LACP-supported interface. To reset the timeout rate to its default, use the no lacp rate command. |
| Step 5 |
end Example: |
Returns to privileged EXEC mode. |
| Step 6 |
show lacp internal Example: |
Verifies your configuration. |
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
||
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
||
| Step 3 |
[no] port-channel auto Example: |
Enables the auto-LAG feature on a switch globally. Use the no form of this command to disable the auto-LAG feature on the switch globally.
|
||
| Step 4 |
end Example: |
Returns to privileged EXEC mode. |
||
| Step 5 |
show etherchannel auto Example: |
Displays that EtherChannel is created automatically. |
| Command or Action | Purpose | |||
|---|---|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
||
| Step 2 |
configure terminal Example: |
Enters global configuration mode. |
||
| Step 3 |
interface interface-id Example: |
Specifies the port interface to be enabled for auto-LAG, and enters interface configuration mode. |
||
| Step 4 |
[no] channel-group auto Example: |
(Optional) Enables auto-LAG feature on individual port interface. Use the no form of this command to disable the auto-LAG feature on individual port interface.
|
||
| Step 5 |
end Example: |
Returns to privileged EXEC mode. |
||
| Step 6 |
show etherchannel auto Example: |
Displays that EtherChannel is created automatically. |
You use the persistence command to convert the auto created EtherChannel into a manual one and allow you to add configuration on the existing EtherChannel.
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable Example: |
Enables privileged EXEC mode. Enter your password if prompted. |
| Step 2 |
port-channel channel-number persistent Example: |
Converts the auto created EtherChannel into a manual one and allows you to add configuration on the EtherChannel. |
| Step 3 |
show etherchannel summary Example: |
Displays the EtherChannel information. |
You can display EtherChannel, PAgP, and LACP status using the commands listed in this table.
|
Command |
Description |
|---|---|
|
clear lacp { channel-group-number counters | counters } |
Clears LACP channel-group information and traffic counters. |
|
clear pagp { channel-group-number counters | counters } |
Clears PAgP channel-group information and traffic counters. |
|
show etherchannel [ channel-group-number { detail | load-balance | port | port-channel | protocol | summary }] [ detail | load-balance | port | port-channel | protocol | auto | 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, protocol, and Auto-LAG information. |
|
show pagp [ channel-group-number ] { counters | internal | neighbor } |
Displays PAgP information such as traffic information, the internal PAgP configuration, and neighbor information. |
|
show pagp [ channel-group-number ] dual-active |
Displays the dual-active detection status. |
|
show lacp [ channel-group-number ] { counters | internal | neighbor | sys-id } |
Displays LACP information such as traffic information, the internal LACP configuration, and neighbor information. |
|
show running-config |
Verifies your configuration entries. |
|
show etherchannel load-balance |
Displays the load balance or frame distribution scheme among ports in the port channel. |
This section provides configuration examples for configuring EtherChannels:
This example shows how to configure an EtherChannel on a single device. It assigns two ports as static-access ports in VLAN 10 to channel 5 with the PAgP mode desirable :
Device# configure terminal
Device(config)# interface range gigabitethernet 1/0/1 - 2
Device(config-if-range)# switchport mode access
Device(config-if-range)# switchport access vlan 10
Device(config-if-range)# channel-group 5 mode desirable non-silent
Device(config-if-range)# end
This example shows how to configure an EtherChannel on a single device. It assigns two ports as static-access ports in VLAN 10 to channel 5 with the LACP mode active:
Device# configure terminal
Device(config)# interface range gigabitethernet 1/0/1 - 2
Device(config-if-range)# switchport mode access
Device(config-if-range)# switchport access vlan 10
Device(config-if-range)# channel-group 5 mode active
Device(config-if-range)# end
PoE or LACP negotiation errors may occur if you configure two ports from switch to the access point (AP). This scenario can be avoided if the port channel configuration is on the switch side. For more details, see the following example:
interface Port-channel1
switchport access vlan 20
switchport mode access
switchport nonegotiate
no port-channel standalone-disable <--this one
spanning-tree portfast
Note |
If the port reports LACP errors on port flap, you should include the following command as well: no errdisable detect cause pagp-flap |
This example shows how to configure Auto-LAG on a switch
Device> enable
Device# configure terminal
Device(config)# port-channel auto
Device(config-if)# end
Device# show etherchannel autoThe following example shows the summary of EtherChannel that was created automatically.
Device# show etherchannel auto
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use f - failed to allocate aggregator
M - not in use, minimum links not met
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
A - formed by Auto LAG
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SUA) LACP Gi1/0/45(P) Gi2/0/21(P) Gi3/0/21(P)
The following example shows the summary of auto EtherChannel after executing the port-channel 1 persistent command .
Device# port-channel 1 persistent
Device# show etherchannel summary
Switch# show etherchannel summary
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use f - failed to allocate aggregator
M - not in use, minimum links not met
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
A - formed by Auto LAG
Number of channel-groups in use: 1
Number of aggregators: 1
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SU) LACP Gi1/0/45(P) Gi2/0/21(P) Gi3/0/21(P)
This example shows how to configure LACP port-channel min-links:
Device > enable
Device# configure terminal
Device(config)# interface port-channel 5
Device(config-if)# port-channel min-links 3
Device# show etherchannel 25 summary
Device# endWhen the minimum links requirement is not met in standalone switches, the port-channel is flagged and assigned SM/SN or RM/RN state.
Device# show etherchannel 5 summary
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use N- not in use, no aggregration
f - failed to allocate aggregator
M - not in use, no aggregation due to minimum links not met
m- not in use, port not aggregated due to minimum links not met
u - unsuitable for bundling
w - waiting to be aggregated
d - default port
Number of channel-groups in use: 6
Number of aggregators: 6
Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
6 Po25(RM) LACP Gi1/3/1(D) Gi1/3/2(D) Gi2/2/25(D) Gi2/2/26(W)
This example shows you how to configure the LACP rate:
Device> enable
Device# configure terminal
Device(config)# interface gigabitethernet 2/0/1
Device(config-if)# lacp rate fast
Device(config-if)# exit
Device(config)# end
Device# show lacp internal
Device# show lacp counters
The following is sample output from the show lacp internal command:
Device# show lacp internal
Flags: S - Device is requesting Slow LACPDUs
F - Device is requesting Fast LACPDUs
A - Device is in Active mode P - Device is in Passive mode
Channel group 6
LACP port Admin Oper Port Port
Port Flags State Priority Key Key Number State
Te1/49 FA bndl 32768 0x19 0x19 0x32 0x3F
Te1/50 FA bndl 32768 0x19 0x19 0x33 0x3F
Te1/51 FA bndl 32768 0x19 0x19 0x34 0x3F
Te1/52 FA bndl 32768 0x19 0x19 0x35 0x3F
The following is sample output from the show lacp counters command:
Device# show lacp counters
LACPDUs Marker Marker Response LACPDUs
Port Sent Recv Sent Recv Sent Recv Pkts Err
---------------------------------------------------------------------
Channel group: 6
Te1/1/27 2 2 0 0 0 0 0
Te2/1/25 2 2 0 0 0 0 0
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use the Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.|
Feature Name |
Releases |
Feature Information |
|---|---|---|
|
Configuring EtherChannels |
|
The feature was introduced. |
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