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Table Of Contents
PAgP Interaction with Other Features
Link Aggregation Control Protocol
LACP Interaction with Other Features
Load Balancing and Forwarding Methods
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 LACP Maximum Bundles
Configuring LACP Fast Switchover
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.
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Understanding EtherChannels
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EtherChannel Overview
An EtherChannel consists of individual ports bundled into a single logical link as shown in Figure 36-1.
Figure 36-1 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:
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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:
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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.
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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 36-2.
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 36-2 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 36-1 shows the user-configurable EtherChannel PAgP modes for the channel-group interface configuration command on an port.
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:
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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 36-2 shows the user-configurable EtherChannel LACP modes for the channel-group interface configuration command on a port.
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:
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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
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 36-3, 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 36-3 Load Distribution and Forwarding Methods
Configuring EtherChannels
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Default EtherChannel Configuration
Table 36-3 shows the default EtherChannel configuration.
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:
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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.
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Beginning in privileged EXEC mode, follow these steps to assign a Layer 2 Ethernet port to a Layer 2 EtherChannel. This procedure is required.
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.
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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:
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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 terminalSwitch(config)# interface range gigabitethernet0/1 -2Switch(config-if-range)# switchport mode accessSwitch(config-if-range)# switchport access vlan 10Switch(config-if-range)# channel-group 5 mode desirable non-silentSwitch(config-if-range)# endThis 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 terminalSwitch(config)# interface range gigabitethernet0/1 -2Switch(config-if-range)# switchport mode accessSwitch(config-if-range)# switchport access vlan 10Switch(config-if-range)# channel-group 5 mode activeSwitch(config-if-range)# endConfiguring 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
Beginning in privileged EXEC mode, follow these steps to create a port-channel interface for a Layer 3 EtherChannel. This procedure is required.
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 terminalSwitch(config)# interface port-channel 5Switch(config-if)# no switchportSwitch(config-if)# ip address 172.10.20.10 255.255.255.0Switch(config-if)# endConfiguring 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.
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:
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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 terminalSwitch(config)# interface range gigabitethernet0/1 -2Switch(config-if-range)# no ip addressSwitch(config-if-range)# no switchportSwitch(config-if-range)# channel-group 5 mode activeSwitch(config-if-range)# endConfiguring 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.
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
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.
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
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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. A maximum of 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):
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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.
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).
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Beginning in privileged EXEC mode, follow these steps to configure the LACP port priority. This procedure is optional.
To return the LACP port priority to the default value, use the no lacp port-priority interface configuration command.
Configuring LACP Maximum Bundles
You can configure the maximum number of members that can be bundled. Any members in excess of this maximum number are kept in hot-standby state and are transitioned to bundled state when one of the bundled members goes down.
To configure the LACP maximum number of ports to bundle in a port channel, complete these steps:
Configuration Example
This example shows the maximum number of bundles is 1 on port channel 10.
Switch# show running-config interface port-channel 10Building configuration...Current configuration : 228 bytes!interface Port-channel10lacp max-bundle 1endUse this command to show the status of hot-standby interfaces.
Switch# show etherchannel summaryFlags: D - down P - bundled in port-channelI - stand-alone s - suspendedH - Hot-standby (LACP only)R - Layer3 S - Layer2U - in use f - failed to allocate aggregatorM - not in use, minimum links not metu - unsuitable for bundlingw - waiting to be aggregatedd - default portNumber of channel-groups in use: 1Number of aggregators: 1Group Port-channel Protocol Ports------+-------------+-----------+---------------------------------------------10 Po10(SU) LACP Gi0/1(P) Gi0/3(H)Switch# show lacp internalFlags: S - Device is requesting Slow LACPDUsF - Device is requesting Fast LACPDUsA - Device is in Active mode P - Device is in Passive modeChannel group 10LACP port Admin Oper Port PortPort Flags State Priority Key Key Number StateGi0/1 SA bndl 32768 0xA 0xA 0x102 0x3DGi0/3 FA hot-stby 32768 0xA 0xA 0x104 0x7Configuring LACP Fast Switchover
When a port from a hot-standby state moves to a bundled state, the default time is two seconds. Enabling fast switchover on the port channel changes this time to 50 ms. This faster time allows the port to quickly transition to the bundled state, and the port channel continues to stay up.
To enable LACP fast switchover on a port channel, complete these steps:
Configuration Example
Use the commands in these examples to show that fast switchover is enabled.
Switch# show etherchannel 10 port-channelPort-channels in the group:----------------------Port-channel: Po6 (Primary Aggregator)------------Age of the Port-channel = 0d:01h:54m:42sLogical slot/port = 14/3 Number of ports = 1Port state = Port-channel Ag-InuseProtocol = LACPFast-switchover = enabledPorts in the Port-channel:Index Load Port EC state No of bits------+------+------+------------------+-----------0 FF Gi0/1 Active 8Time since last port bundled: 0d:01h:54m:03s Fa2/44Switch# show etherchannel 10 detailGroup state = L2Ports: 2 Maxports = 16Port-channels: 1 Max Port-channels = 16Protocol: LACPMinimum Links: 0Ports in the group:-------------------...<snip>...Port-channels in the group:----------------------Port-channel: Po6 (Primary Aggregator)------------Age of the Port-channel = 0d:02h:14m:09sLogical slot/port = 14/3 Number of ports = 1Port state = Port-channel Ag-InuseProtocol = LACPFast-switchover = enabledPorts in the Port-channel:Index Load Port EC state No of bits------+------+------+------------------+-----------0 FF Fa0/1 Active 8Time since last port bundled: 0d:02h:13m:30s Fa2/44Configuring LACP Fast Rate
To assist with early detection of a member link failure, you can request the peer to send LACPDUs at a rate of one second. The default rate is 30 seconds.
To enable LACP fast rate, complete these steps:
Configuration Example
This example shows that fast rate is configured.
Switch# show lacp internalFlags: S - Device is requesting Slow LACPDUsF - Device is requesting Fast LACPDUsA - Device is in Active mode P - Device is in Passive modeChannel group 10LACP port Admin Oper Port PortPort Flags State Priority Key Key Number StateGi0/1 FA bndl 32768 0xA 0xA 0x102 0x7DConfiguring 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:
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
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 terminalSwitch(config)# interface port-channel 1Switch(config-if)# port-channel min-links 2Switch(config-if)# endThis example shows the output from the show etherchannel port-channel interface detail command:
Switch# show etherchannel 10 detailGroup state = L2Ports: 3 Maxports = 16Port-channels: 1 Max Port-channels = 16Protocol: LACPMinimum Links: 3Ports in the group:-------------------Port: Gi0/12------------Port state = Up Mstr In-BndlChannel group = 10 Mode = Active Gcchange = -Port-channel = Po10 GC = - Pseudo port-channel = Po10Port index = 0 Load = 0x00 Protocol = LACPMode = LACPFlags: 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 PortPort Flags State Priority Key Key Number StateGi0/12 SA bndl 32768 0xA 0xA 0x10D 0x3DPartner's information:Partner Partner LACP Partner Partner Partner Partner PartnerPort Flags State Port Priority Admin Key Oper Key Port Number Port StateGi0/12 SA bndl 32768 0x0 0xA 0x114 0x3DAge of the port in the current state: 1d:00h:24m:51sPort: Gi0/13------------Port state = Up Mstr In-BndlChannel group = 10 Mode = Active Gcchange = -Port-channel = Po10 GC = - Pseudo port-channel = Po10Port index = 0 Load = 0x00 Protocol = LACPMode = LACPFlags: 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 PortPort Flags State Priority Key Key Number StateGi0/13 SA bndl 32768 0xA 0xA 0x10E 0x3DPartner's information:Partner Partner LACP Partner Partner Partner Partner PartnerPort Flags State Port Priority Admin Key Oper Key Port Number Port StateGi0/13 SA bndl 32768 0x0 0xA 0x104 0x3DAge of the port in the current state: 1d:00h:24m:48sPort: Gi0/20------------Port state = Up Mstr In-BndlChannel group = 10 Mode = Active Gcchange = -Port-channel = Po10 GC = - Pseudo port-channel = Po10Port index = 0 Load = 0x00 Protocol = LACPMode = LACPFlags: 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 PortPort Flags State Priority Key Key Number StateGi0/20 SA bndl 32768 0xA 0xA 0x115 0x3DPartner's information:Partner Partner LACP Partner Partner Partner Partner PartnerPort Flags State Port Priority Admin Key Oper Key Port Number Port StateGi0/20 SA bndl 32768 0x0 0xA 0x115 0x3DAge of the port in the current state: 1d:00h:24m:43sPort-channels in the group:----------------------Port-channel: Po10 (Primary Aggregator)------------Age of the Port-channel = 1d:00h:36m:54sLogical slot/port = 2/10 Number of ports = 3HotStandBy port = nullPort state = Port-channel Ag-InuseProtocol = LACPFast-switchover = disabledDirect Load Swap = disabledPorts in the Port-channel:Index Load Port EC state No of bits------+------+--------+------------------+-----------0 00 Gi0/12 Active 00 00 Gi0/13 Active 00 00 Gi0/20 Active 0Time since last port bundled: 1d:00h:24m:43s Gi0/20Time since last port Un-bundled: 1d:00h:24m:45s Gi0/20Last applied Hash Distribution Algorithm: -Channel-group Iedge Counts:--------------------------:Access ref count : 0Iedge session count : 0+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++Switch#009215: 1d00h: %EC-5-MINLINKS_NOTMET: Port-channel Po10 is down bundled ports (2) doesn't meet min-links <<<<<<<<<<< Error message thrown on member009216: 1d00h: %LINK-3-UPDOWN: Interface Port-channel10, changed state to down Link Failure009217: 1d00h: %LINK-3-UPDOWN: Interface GigabitEthernet0/20, changed state to down009218: 1d00h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/20, changed state to down009219: 1d00h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/12, changed state to down009220: 1d00h: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet0/13, changed state to down009221: 1d00h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel10, changed state to down++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++Switch# show etherchannel 10 detailGroup state = L2Ports: 3 Maxports = 16Port-channels: 1 Max Port-channels = 16Protocol: LACPMinimum Links: 3Ports in the group:-------------------Port: Gi0/12------------Port state = Up Mstr In-BndlChannel group = 10 Mode = Active Gcchange = -Port-channel = Po10 GC = - Pseudo port-channel = Po10Port index = 0 Load = 0x00 Protocol = LACPMode = LACPFlags: 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 PortPort Flags State Priority Key Key Number StateGi0/12 SA bndl 32768 0xA 0xA 0x10D 0x3DPartner's information:Partner Partner LACP Partner Partner Partner Partner PartnerPort Flags State Port Priority Admin Key Oper Key Port Number Port StateGi0/12 SA bndl 32768 0x0 0xA 0x114 0x3DAge of the port in the current state: 1d:00h:26m:00sPort: Gi0/13------------Port state = Up Mstr In-BndlChannel group = 10 Mode = Active Gcchange = -Port-channel = Po10 GC = - Pseudo port-channel = Po10Port index = 0 Load = 0x00 Protocol = LACPMode = LACPFlags: 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 PortPort Flags State Priority Key Key Number StateGi0/13 FA bndl 32768 0xA 0xA 0x10E 0x3DPartner's information:Partner Partner LACP Partner Partner Partner Partner PartnerPort Flags State Port Priority Admin Key Oper Key Port Number Port StateGi0/13 SA bndl 32768 0x0 0xA 0x104 0xFAge of the port in the current state: 1d:00h:25m:57sPort: Gi0/20------------Port state = Down Not-in-BndlChannel group = 10 Mode = Active Gcchange = -Port-channel = null GC = - Pseudo port-channel = Po10Port index = 0 Load = 0x00 Protocol = LACPMode = UnknownFlags: 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 PortPort Flags State Priority Key Key Number StateGi0/20 SA down 32768 0xA 0xA 0x115 0x7Partner's information:Partner Partner LACP Partner Partner Partner Partner PartnerPort Flags State Port Priority Admin Key Oper Key Port Number Port StateGi0/20 FP down 32768 0x0 0xA 0x115 0x34Age of the port in the current state: 1d:00h:25m:51sPort-channels in the group:----------------------Port-channel: Po10 (Primary Aggregator)------------Age of the Port-channel = 1d:00h:38m:03sLogical slot/port = 2/10 Number of ports = 2HotStandBy port = nullPort state = Port-channel Ag-MinLink-Not-Inuse <<<<<<<<<<<<<< Reason as to why the link is downProtocol = LACPFast-switchover = disabledDirect Load Swap = disabledPorts in the Port-channel:Index Load Port EC state No of bits------+------+--------+------------------+-----------0 00 Gi0/12 Active 00 00 Gi0/13 Active 0Time since last port bundled: 1d:00h:25m:51s Gi0/20Time since last port Un-bundled: 0d:00h:00m:10s Gi0/20Last applied Hash Distribution Algorithm: -Channel-group Iedge Counts:--------------------------:Access ref count : 0Iedge session count : 0EtherChannels 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 gigabitethernet0/1Switch (config-if)#switchport mode trunkSwitch (config-if)#switchport trunk allowed vlan noneSwitch (config-if)#service instance 1 EthernetSwitch (config-if-srv)#encapsulation untaggedSwitch (config-if-srv)#l2protocol peer lacpSwitch (config-if-srv)#bridge-domain 10Switch (config-if-srv)#endDisplaying EtherChannel, PAgP, and LACP Status
To display EtherChannel, PAgP, and LACP status information, use the privileged EXEC commands described in Table 36-4:
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.
