Guest

Support

Configuring IEEE 802.3ad Link Bundling and Load Balancing

  • Viewing Options

  • PDF (460.8 KB)
  • Feedback
Configuring IEEE 802.3ad Link Bundling and Load Balancing

Contents

Configuring IEEE 802.3ad Link Bundling and Load Balancing

This document describes how the IEEE 802.3ad link bundling and load balancing leverages the EtherChannel infrastructure within Cisco software to manage the bundling of various links. Also described are network traffic load-balancing features to help minimize network disruption that results when a port is added or deleted from a link bundle.

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use 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.

Prerequisites for Configuring IEEE 802.3ad Link Bundling and Load Balancing

  • Knowledge of how EtherChannels and Link Aggregation Control Protocol (LACP) function in a network
  • Knowledge of load balancing to mitigate network traffic disruptions
  • Verification that both ends of the LACP link have the same baseline software version

Restrictions for Configuring IEEE 802.3ad Link Bundling and Load Balancing

  • The number of links supported per bundle is bound by the platform.
  • All links must operate at the same link speed and in full-duplex mode (LACP does not support half-duplex mode).
  • All links must be configured either as EtherChannel links or as LACP links.
  • Only physical interfaces can form aggregations. Aggregations of VLAN interfaces are not possible nor is an aggregation of aggregations.
  • If a router is connected to a switch, the bundle terminates on the switch.
  • An EtherChannel will not form if one of the LAN ports is a Switched Port Analyzer (SPAN) destination port.
  • All ports in an EtherChannel must use the same EtherChannel protocol.
  • The LACP Single Fault Direct Load Balance Swapping feature is limited to a single bundled port failure.
  • The LACP Single Fault Direct Load Balance Swapping feature cannot be used with the Port Aggregation Protocol (PagP).
  • LACP port priority cannot be configured with LACP single fault direct load balance swapping.
  • The adaptive algorithm does not apply to service control engines (SCEs) when EtherChannel load distribution is used.

Information About Configuring IEEE 802.3ad Link Bundling and Load Balancing

Gigabit EtherChannel

Gigabit EtherChannel is high-performance Ethernet technology that provides Gbps transmission rates. A Gigabit EtherChannel bundles individual Gigabit Ethernet links into a single logical link that provides the aggregate bandwidth of up to eight physical links. All LAN ports in each EtherChannel must be the same speed and all must be configured either as Layer 2 or as Layer 3 LAN ports. Inbound broadcast and multicast packets on one link in an EtherChannel are blocked from returning on any other link in the EtherChannel.

When a link within an EtherChannel fails, traffic previously carried over the failed link switches to the remaining links within that EtherChannel. Also when a failure occurs, a trap is sent that identifies the device, the EtherChannel, and the failed link.

Port Channel and LACP-Enabled Interfaces

Each EtherChannel has a numbered port channel interface that, if not already created, is created automatically when the first physical interface is added to the channel group. The configuration of a port channel interface affects all LAN ports assigned to that port channel interface.

To change the parameters of all ports in an EtherChannel, change the configuration of the port channel interface: for example, if you want to configure Spanning Tree Protocol or configure a Layer 2 EtherChannel as a trunk. Any configuration or attribute changes you make to the port channel interface are propagated to all interfaces within the same channel group as the port channel; that is, configuration changes are propagated to the physical interfaces that are not part of the port channel but are part of the channel group.

The configuration of a LAN port affects only that LAN port.

IEEE 802.3ad Link Bundling

The IEEE 802.3ad Link Bundling feature provides a method for aggregating multiple Ethernet links into a single logical channel based on the IEEE 802.3ad standard. This feature helps improve the cost effectiveness of a device by increasing cumulative bandwidth without necessarily requiring hardware upgrades. In addition, IEEE 802.3ad link bundling provides a capability to dynamically provision, manage, and monitor various aggregated links and enables interoperability between various Cisco devices and devices of third-party vendors.

LACP supports the automatic creation of EtherChannels by exchanging LACP packets between LAN ports. LACP packets are exchanged only between ports in passive and active modes. The protocol “learns” the capabilities of LAN port groups dynamically and informs the other LAN ports. After LACP identifies correctly matched Ethernet links, it facilitates grouping the links into an EtherChannel. Then the EtherChannel is added to the spanning tree as a single bridge port.

Both the passive and active modes allow LACP to negotiate between LAN ports to determine if they can form an EtherChannel, based on criteria such as port speed and trunking state. (Layer 2 EtherChannels also use VLAN numbers.) LAN ports can form an EtherChannel when they are in compatible LACP modes, as in the following examples:

  • A LAN port in active mode can form an EtherChannel with another LAN port that is in active mode.
  • A LAN port in active mode can form an EtherChannel with another LAN port that is in passive mode.
  • A LAN port in passive mode cannot form an EtherChannel with another LAN port that is also in passive mode because neither port will initiate negotiation.

LACP uses the following parameters:

  • LACP system priority—You must configure an LACP system priority on each device running LACP. The system priority can be configured automatically or through the command-line interface (CLI). LACP uses the system priority with the device MAC address to form the system ID and also during negotiation with other systems.
  • LACP port priority—You must configure an LACP port priority on each port configured to use LACP. The port priority can be configured automatically or through the CLI. LACP uses the port priority to decide which ports should be put in standby mode when there is a hardware limitation that prevents all compatible ports from aggregating. LACP also uses the port priority with the port number to form the port identifier.
  • LACP administrative key—LACP automatically configures an administrative key value on each port configured to use LACP. The administrative key defines the ability of a port to aggregate with other ports. A port’s ability to aggregate with other ports is determined by the following:
    • Port physical characteristics such as data rate, duplex capability, and point-to-point or shared medium
    • Configuration restrictions that you establish

LACP, on ports configured to use it, tries to configure the maximum number of compatible ports in an EtherChannel, up to the maximum allowed by the hardware. To use the hot standby feature in the event a channel port fails, both ends of the LACP bundle must support the lacp max-bundle command.

As a control protocol, LACP uses the Slow Protocol multicast address of 01-80-C2-00-00-02 to transmit LACP protocol data units (PDUs). Operations, administration, and maintenance (OAM) packets also use the Slow Protocol link type. Subsequently, a subtype field is defined per the IEEE 802.3ad standard (Annex 43B, section 4) differentiating LACP PDUs from OAM PDUs.

Benefits of IEEE 802.3ad Link Bundling

  • Increased network capacity without changing physical connections or upgrading hardware
  • Cost savings from the use of existing hardware and software for additional functions
  • A standard solution that enables interoperability of network devices
  • Port redundancy without user intervention when an operational port fails

EtherChannel Load Balancing

EtherChannel load balancing can use MAC addresses; IP addresses; Layer 4 port numbers; either source addresses, destination addresses, or both; or ports. The selected mode applies to all EtherChannels configured on the device.

Traffic load across the links in an EtherChannel is balanced 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. When a port is added to an EtherChannel or an active port fails, the load balance bits are reset and reassigned for all ports within that EtherChannel and reprogrammed into the ASIC for each port. This reset causes packet loss during the time the reassignment and reprogramming is taking place. The greater the port bandwidth, the greater the packet loss.

Load Distribution in an EtherChannel

In earlier Cisco software releases, only a fixed load distribution algorithm was supported. With this fixed algorithm, the load share bits are assigned sequentially to each port in the bundle. Consequently, the load share bits for existing ports change when a member link joins or leaves the bundle. When these values are programmed in the ASIC, substantial traffic disruption and, in some cases, duplication of traffic can occur.

The EtherChannel Load Distribution feature enhances the load distribution mechanism with the adaptive load distribution algorithm. This algorithm uses a port reassignment scheme that enhances EtherChannel availability by limiting the load distribution reassignment to the port that is added or deleted. The new load on existing bundled ports does not conflict with the load programmed on those ports when a port is added or deleted.

You can enable this feature in either global configuration mode or interface configuration mode. The algorithm is applied at the next hash-distribution instance, which usually occurs when a link fails, is activated, added, or removed, or when shutdown or no shutdown is configured.

Because the selected algorithm is not applied until the next hash-distribution instance, the current and configured algorithms could be different. If the algorithms are different, a message is displayed alerting you to take appropriate action. For example:

Device(config-if)# port-channel port hash-distribution fixed 
This command will take effect upon a member link UP/DOWN/ADDITION/DELETION event.
Please do a shut/no shut to take immediate effect

Also, the output of the show etherchannel command is enhanced to show the applied algorithm when the channel group number is specified. This output enhancement is not available, though, when the protocol is also specified because only protocol-specific information is included. Following is an example of output showing the applied algorithm:

Device# show etherchannel 10 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 aggregation
        f - failed to allocate aggregator
<snip>
Group  Port-channel  Protocol    Ports
------+-------------+-----------+-----------------------------------------------
10     Po10(RU)        LACP      Gi3/7(P)       Gi3/9(P)       
! The following line of output is added with support 
of the EtherChannel Load Distribution feature. !
Last applied Hash Distribution Algorithm: Fixed

How to Configure IEEE 802.3ad Link Bundling and Load Balancing

Enabling LACP

SUMMARY STEPS

    1.    enable

    2.    configure terminal

    3.    interface port-channel channel-number

    4.    channel-group channel-group-number mode {active | passive}

    5.    end


DETAILED STEPS
      Command or Action Purpose
    Step 1 enable


    Example:
    Device> enable
     

    Enables privileged EXEC mode.

    • Enter your password if prompted.
     
    Step 2 configure terminal


    Example:
    Device# configure terminal
     

    Enters global configuration mode.

     
    Step 3 interface port-channel channel-number


    Example:
    Device(config)# interface port-channel 10
     

    Identifies the interface port channel and enters interface configuration mode.

     
    Step 4 channel-group channel-group-number mode {active | passive}


    Example:
    Device(config-if)# channel-group 25 mode active
     

    Configures the interface in a channel group and sets it as active.

    • In active mode, the port initiates negotiations with other ports by sending Link Aggregate Control Protocol (LACP) packets.
     
    Step 5 end


    Example:
    Device(config-if)# end
     

    Returns to privileged EXEC mode.

     

    Configuring a Port Channel

    You must manually create a port channel logical interface. Perform this task to configure a port channel.

    SUMMARY STEPS

      1.    enable

      2.    configure terminal

      3.    interface port-channel channel-number

      4.    ip address ip-address mask

      5.    end

      6.    show running-config interface port-channel group-number


    DETAILED STEPS
        Command or Action Purpose
      Step 1 enable


      Example:
      Device> enable
       

      Enables privileged EXEC mode.

      • Enter your password if prompted.
       
      Step 2 configure terminal


      Example:
      Device# configure terminal
       

      Enters global configuration mode.

       
      Step 3 interface port-channel channel-number


      Example:
      Device(config)# interface port-channel 10
       

      Identifies the interface port channel and enters interface configuration mode.

       
      Step 4 ip address ip-address mask


      Example:
      Device(config-if)# ip address 172.31.52.10 255.255.255.0
       

      Assigns an IP address and subnet mask to the EtherChannel.

       
      Step 5 end


      Example:
      Device(config-if)# end
       

      Returns to privileged EXEC mode.

       
      Step 6 show running-config interface port-channel group-number


      Example:
      Device# show running-config interface port-channel 10
       

      Displays the port channel configuration.

       

      Example

      This example shows how to verify the configuration:

      Device# show running-config interface port-channel10
       
      Building configuration...
      Current configuration:
      !
      interface Port-channel10
       ip address 172.31.52.10 255.255.255.0
       no ip directed-broadcast
      end

      Associating a Channel Group with a Port Channel

      SUMMARY STEPS

        1.    enable

        2.    configure terminal

        3.    interface port-channel channel -number

        4.    channel-group channel-group-number mode {active | passive}

        5.    end


      DETAILED STEPS
          Command or Action Purpose
        Step 1 enable


        Example:
        Device> enable
         

        Enables privileged EXEC mode.

        • Enter your password if prompted.
         
        Step 2 configure terminal


        Example:
        Device# configure terminal
         

        Enters global configuration mode.

         
        Step 3 interface port-channel channel -number


        Example:
        Device(config)# interface port-channel 5
         

        Creates a port channel and enters interface configuration mode.

         
        Step 4 channel-group channel-group-number mode {active | passive}


        Example:
        Device(config-if)# channel-group 5 mode active
         

        Includes the interface as part of the port channel bundle.

         
        Step 5 end


        Example:
        Device(config-if)# end
         

        Returns to privileged EXEC mode.

         

        Setting LACP System Priority

        Perform this task to set the Link Aggregation Control Protocol (LACP) system priority. The system ID is the combination of the LACP system priority and the MAC address of a device.

        SUMMARY STEPS

          1.    enable

          2.    configure terminal

          3.    lacp system-priority priority

          4.    end

          5.    show lacp sys-id


        DETAILED STEPS
            Command or Action Purpose
          Step 1 enable


          Example:
          Device> enable
           

          Enables privileged EXEC mode.

          • Enter your password if prompted.
           
          Step 2 configure terminal


          Example:
          Device# configure terminal
           

          Enters global configuration mode.

           
          Step 3 lacp system-priority priority


          Example:
          Device(config)# lacp system-priority 200
           

          Sets the system priority.

           
          Step 4 end


          Example:
          Device(config)# end
           

          Returns to privileged EXEC mode.

           
          Step 5 show lacp sys-id


          Example:
          Device# show lacp sys-id
           

          Displays the system ID, which is a combination of the system priority and the MAC address of the device.

           

          Example

          This example shows how to verify the LACP configuration:

          Device# show lacp sys-id
          20369,01b2.05ab.ccd0

          Adding and Removing Interfaces from a Bundle

          SUMMARY STEPS

            1.    enable

            2.    configure terminal

            3.    interface type number

            4.    channel-group channel-group-number mode {active | passive}

            5.    no channel-group

            6.    end


          DETAILED STEPS
              Command or Action Purpose
            Step 1 enable


            Example:
            Device> enable
             

            Enables privileged EXEC mode.

            • Enter your password if prompted.
             
            Step 2 configure terminal


            Example:
            Device# configure terminal
             

            Enters global configuration mode.

             
            Step 3 interface type number


            Example:
            Device(config)# interface gigabitethernet 5/0/0
             

            Configures an interface and enters interface configuration mode.

             
            Step 4 channel-group channel-group-number mode {active | passive}


            Example:
            Device(config-if)# channel-group 5 mode active
             

            Adds an interface to a channel group.

             
            Step 5 no channel-group


            Example:
            Device(config-if)# no channel-group 
             

            Removes the interface from the channel group.

             
            Step 6 end


            Example:
            Device(config-if)# end
             

            Returns to privileged EXEC mode.

             

            Monitoring LACP Status

            SUMMARY STEPS

              1.    enable

              2.    show lacp {number | counters | internal | neighbor | sys-id}


            DETAILED STEPS
                Command or Action Purpose
              Step 1 enable


              Example:
              Device> enable
               

              Enables privileged EXEC mode.

              • Enter your password if prompted.
               
              Step 2 show lacp {number | counters | internal | neighbor | sys-id}


              Example:
              Device# show lacp internal
               

              Displays internal device information.

               

              Troubleshooting Tips

              To verify and isolate a fault, start at the highest level maintenance domain and do the following:

              • Check the device error status.
              • When an error exists, perform a loopback test to confirm the error.
              • Run a traceroute to the destination to isolate the fault.
              • If the fault is identified, correct the fault.
              • If the fault is not identified, go to the next lower maintenance domain and repeat these four steps at that maintenance domain level.
              • Repeat the first four steps, as needed, to identify and correct the fault.

              Configuration Examples for IEEE 802.3ad Link Bundling and Load Balancing

              Example: Associating a Channel Group with a Port Channel

              This example shows how to configure channel group number 5 and include it in the channel group:

              Device# configure terminal
              Enter configuration commands, one per line.  End with CNTL/Z.
              Device(config)# interface port-channel5
              Device(config-if)#
              *Aug 20 17:06:14.417: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel5, changed state to down
              *Aug 20 17:06:25.413: %LINK-3-UPDOWN: Interface Port-channel5, changed state to down
              Device(config-if)#
              Device(config-if)# channel-group 5 mode active
              Device(config-if)#
              *Aug 20 17:07:43.713: %LINK-3-UPDOWN: Interface GigabitEthernet7/0/0, changed state to down
              *Aug 20 17:07:44.713: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet7/0/0, changed state to down
              *Aug 20 17:07:45.093: %C10K_ALARM-6-INFO: ASSERT CRITICAL GigE 7/0/0 Physical Port Link Down 
              *Aug 20 17:07:45.093: %C10K_ALARM-6-INFO: CLEAR CRITICAL GigE 7/0/0 Physical Port Link Down 
              *Aug 20 17:07:47.093: %LINK-3-UPDOWN: Interface GigabitEthernet7/0/0, changed state to up
              *Aug 20 17:07:48.093: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet7/0/0, changed state to up
              *Aug 20 17:07:48.957: GigabitEthernet7/0/0 added as member-1 to port-channel5
               
              *Aug 20 17:07:51.957: %LINEPROTO-5-UPDOWN: Line protocol on Interface Port-channel5, changed state to up
              Device(config-if)# end
              Device#
              *Aug 20 17:08:00.933: %SYS-5-CONFIG_I: Configured from console by console
              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 5
                                          LACP port     Admin     Oper    Port        Port
              Port      Flags   State     Priority      Key       Key     Number      State
              Gi7/0/0   SA      bndl      32768         0x5       0x5     0x43        0x3D  
              Device# show interface port-channel5
              Port-channel5 is up, line protocol is up 
                Hardware is GEChannel, address is 0014.a93d.4aa8 (bia 0000.0000.0000)
                MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec, 
                   reliability 255/255, txload 1/255, rxload 1/255
                Encapsulation ARPA, loopback not set
                Keepalive set (10 sec)
                ARP type: ARPA, ARP Timeout 04:00:00
                  No. of active members in this channel: 1 
                      Member 0 : GigabitEthernet7/0/0 , Full-duplex, 1000Mb/s
                Last input 00:00:05, output never, output hang never
                Last clearing of "show interface" counters never
                Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
                Interface Port-channel5 queueing strategy: PXF First-In-First-Out
                Output queue 0/8192, 0 drops; input queue 0/75, 0 drops
                5 minute input rate 0 bits/sec, 0 packets/sec
                5 minute output rate 0 bits/sec, 0 packets/sec
                   0 packets input, 0 bytes, 0 no buffer
                   Received 0 broadcasts (0 IP multicasts)
                   0 runts, 0 giants, 0 throttles
                   0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
                   0 watchdog, 0 multicast, 0 pause input
                   9 packets output, 924 bytes, 0 underruns
                   0 output errors, 0 collisions, 0 interface resets
                   0 babbles, 0 late collision, 0 deferred
                   0 lost carrier, 0 no carrier, 0 PAUSE output
                   0 output buffer failures, 0 output buffers swapped out

              Example: Adding and Removing Interfaces from a Bundle

              The following example shows how to add an interface to a bundle:

              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 5
                                          LACP port     Admin     Oper    Port        Port
              Port      Flags   State     Priority      Key       Key     Number      State
              Gi7/0/0   SA      bndl      32768         0x5       0x5     0x43        0x3D  
              Device# configure terminal
              Enter configuration commands, one per line.  End with CNTL/Z.
              Device(config)# interface gigabitethernet 5/0/0
              Device(config-if)# channel-group 5 mode active
              Device(config-if)#
              *Aug 20 17:10:19.057: %LINK-3-UPDOWN: Interface GigabitEthernet5/0/0, changed state to down
              *Aug 20 17:10:19.469: %C10K_ALARM-6-INFO: ASSERT CRITICAL GigE 5/0/0 Physical Port Link Down 
              *Aug 20 17:10:19.473: %C10K_ALARM-6-INFO: CLEAR CRITICAL GigE 5/0/0 Physical Port Link Down 
              *Aug 20 17:10:21.473: %LINK-3-UPDOWN: Interface GigabitEthernet5/0/0, changed state to up
              *Aug 20 17:10:21.473: GigabitEthernet7/0/0 taken out of port-channel5
              *Aug 20 17:10:23.413: GigabitEthernet5/0/0 added as member-1 to port-channel5
               
              *Aug 20 17:10:23.473: %LINK-3-UPDOWN: Interface Port-channel5, changed state to up
              Device(config-if)# end
              Device#
              *Aug 20 17:10:27.653: %SYS-5-CONFIG_I: Configured from console by console
              *Aug 20 17:11:40.717: GigabitEthernet7/0/0 added as member-2 to port-channel5
               
              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 5
                                          LACP port     Admin     Oper    Port        Port
              Port      Flags   State     Priority      Key       Key     Number      State
              Gi7/0/0   SA      bndl      32768         0x5       0x5     0x43        0x3D  
              Gi5/0/0   SA      bndl      32768         0x5       0x5     0x42        0x3D  
              Device# show interface port-channel5
              Port-channel5 is up, line protocol is up 
                Hardware is GEChannel, address is 0014.a93d.4aa8 (bia 0000.0000.0000)
                MTU 1500 bytes, BW 2000000 Kbit, DLY 10 usec, 
                   reliability 255/255, txload 1/255, rxload 1/255
                Encapsulation ARPA, loopback not set
                Keepalive set (10 sec)
                ARP type: ARPA, ARP Timeout 04:00:00
                  No. of active members in this channel: 2 
                      Member 0 : GigabitEthernet5/0/0 , Full-duplex, 1000Mb/s  <---- added to port channel bundle
                      Member 1 : GigabitEthernet7/0/0 , Full-duplex, 1000Mb/s  
                Last input 00:00:00, output never, output hang never
                Last clearing of "show interface" counters never
                Input queue: 0/150/0/0 (size/max/drops/flushes); Total output drops: 0
                Interface Port-channel5 queueing strategy: PXF First-In-First-Out
                Output queue 0/8192, 0 drops; input queue 0/150, 0 drops
                5 minute input rate 0 bits/sec, 0 packets/sec
                5 minute output rate 0 bits/sec, 0 packets/sec
                   0 packets input, 0 bytes, 0 no buffer
                   Received 0 broadcasts (0 IP multicasts)
                   0 runts, 0 giants, 0 throttles
                   0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
                   0 watchdog, 0 multicast, 0 pause input
                   104 packets output, 8544 bytes, 0 underruns
                   0 output errors, 0 collisions, 0 interface resets
                   0 babbles, 0 late collision, 0 deferred
                   0 lost carrier, 0 no carrier, 0 PAUSE output
                   0 output buffer failures, 0 output buffers swapped out
              

              The following example shows how to remove an interface from a bundle:

              Device# configure terminal
              Enter configuration commands, one per line.  End with CNTL/Z.
              Device(config)# interface gigabitethernet 7/0/0
              Device(config-if)# no channel-group
              Device(config-if)#
              *Aug 20 17:15:49.433: GigabitEthernet7/0/0 taken out of port-channel5
              *Aug 20 17:15:49.557: %C10K_ALARM-6-INFO: ASSERT CRITICAL GigE 5/0/0 Physical Port Link Down 
              *Aug 20 17:15:50.161: %C10K_ALARM-6-INFO: CLEAR CRITICAL GigE 5/0/0 Physical Port Link Down 
              *Aug 20 17:15:51.433: %LINK-3-UPDOWN: Interface GigabitEthernet7/0/0, changed state to down
              *Aug 20 17:15:52.433: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet7/0/0, changed state to down
              Device(config-if)# end
              Device#
              *Aug 20 17:15:58.209: %SYS-5-CONFIG_I: Configured from console by console
              Device#
              *Aug 20 17:15:59.257: %C10K_ALARM-6-INFO: ASSERT CRITICAL GigE 7/0/0 Physical Port Link Down 
              *Aug 20 17:15:59.257: %C10K_ALARM-6-INFO: CLEAR CRITICAL GigE 7/0/0 Physical Port Link Down   
              Device#
              *Aug 20 17:16:01.257: %LINK-3-UPDOWN: Interface GigabitEthernet7/0/0, changed state to up
              *Aug 20 17:16:02.257: %LINEPROTO-5-UPDOWN: Line protocol on Interface GigabitEthernet7/0/0, changed state to up
              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 5
                                          LACP port     Admin     Oper    Port        Port
              Port      Flags   State     Priority      Key       Key     Number      State
              Gi5/0/0   SA      bndl      32768         0x5       0x5     0x42        0x3D  

              Example: Monitoring LACP Status

              The following example shows Link Aggregation Protocol (LACP) activity that you can monitor by using the show lacp 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 5
                                          LACP port     Admin     Oper    Port        Port
              Port      Flags   State     Priority      Key       Key     Number      State
              Gi5/0/0   SA      bndl      32768         0x5       0x5     0x42        0x3D  
              Device# show lacp 5 counters
                           LACPDUs         Marker      Marker Response    LACPDUs
              Port       Sent   Recv     Sent   Recv     Sent   Recv      Pkts Err
              ---------------------------------------------------------------------
              Channel group: 5
              Gi5/0/0     21     18       0      0        0      0         0     
              Device# show lacp 5 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 5
                                          LACP port     Admin     Oper    Port        Port
              Port      Flags   State     Priority      Key       Key     Number      State
              Gi5/0/0   SA      bndl      32768         0x5       0x5     0x42        0x3D  
              Device# show lacp 5 neighbor
              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 5 neighbors
              Partner's information:
                        Partner Partner   LACP Partner  Partner   Partner  Partner     Partner
              Port      Flags   State     Port Priority Admin Key Oper Key Port Number Port State
              Gi5/0/0   SP      32768     0011.2026.7300  11s    0x1     0x14     0x3C  
              Device# show lacp counters
                           LACPDUs         Marker      Marker Response    LACPDUs
              Port       Sent   Recv     Sent   Recv     Sent   Recv      Pkts Err
              ---------------------------------------------------------------------
              Channel group: 5
              Gi5/0/0     23     20       0      0        0      0         0     
              Device# show lacp sys-id
              32768,0014.a93d.4a00

              Additional References for IEEE 802.3ad Link Bundling and Load Balancing

              Related Documents

              Related Topic

              Document Title

              Configuring EtherChannels

              “Configuring Layer 3 and Layer 2 EtherChannel” chapter of the Catalyst 6500 Release 12.2SXF Software Configuration Guide

              Configuring the Cisco Catalyst 3850 Series Switch

              Catalyst 3850 Series Switch Configuration Guide

              Configuring Carrier Ethernet

              Carrier Ethernet Configuration Guide

              Link Aggregation Control Protocol (LACP) commands: complete command syntax, command mode, command history, defaults, usage guidelines, and examples

              Cisco IOS Carrier Ethernet Command Reference

              Cisco IOS commands: master list of commands with complete command syntax, command mode, command history, defaults, usage guidelines, and examples

              Cisco IOS Master Command List, All Releases

              Standards

              Standard

              Title

              IEEE 802.3ad-2000

              IEEE 802.3ad-2000 Link Aggregation

              MIBs

              MIB

              MIBs Link

              802.3ad MIB

              To locate and download MIBs for selected platforms, Cisco software releases, and feature sets, use Cisco MIB Locator found at the following URL:

              http:/​/​www.cisco.com/​go/​mibs

              Technical Assistance

              Description

              Link

              The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.

              http:/​/​www.cisco.com/​cisco/​web/​support/​index.html

              Feature Information for Configuring IEEE 802.3ad Link Bundling and Load Balancing

              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 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.

              Table 1 Feature Information for Configuring IEEE 802.3ad Link Bundling and Load Balancing

              Feature Name

              Releases

              Feature Information

              EtherChannel Load Distribution

              12.2(33)SRC

              The EtherChannel Load Distribution feature uses a port reassignment scheme that enhances EtherChannel availability by limiting the load distribution reassignment to the port that is added or deleted. The new load on existing bundled ports does not conflict with the load programmed on those ports when a port is added or deleted.

              The following commands were introduced or modified: port-channel port hash-distribution, show etherchannel.

              EtherChannel Min-Links

              12.2(33)SB

              15.0(1)S

              The EtherChannel Min-Links feature allows a port channel to be shut down when the number of active links falls below the minimum threshold. Using the lacp min-bundle command, you can configure the minimum threshold.

              The following command was introduced or modified: lacp min-bundle.

              IEEE 802.3ad Faster Link Switchover Time

              12.2(33)SB

              The IEEE 802.3ad Faster Link Switchover Time feature provides a link failover time of 250 milliseconds or less and a maximum link failover time of 2 seconds. Also, port channels remain in the LINK_UP state to eliminate reconvergence by the Spanning-Tree Protocol.

              The following command was introduced or modified: lacp fast-switchover.

              IEEE 802.3ad Link Aggregation (LACP)

              12.2(31)SB2

              12.2(33)SRB

              12.2(33)SRC

              15.0(1)S

              The IEEE 802.3ad Link Aggregation feature provides a method for aggregating multiple Ethernet links into a single logical channel based on the IEEE 802.3ad standard. In addition, this feature provides a capability to dynamically provision, manage, and monitor various aggregated links and enables interoperability between various Cisco devices and third-party devices.

              In 12.2(31)SB2, this feature was implemented on the Cisco 10000 series router.

              In 12.2(33)SRB, this feature was implemented on the Cisco 7600 router.

              In 12.2(33)SRC, the lacp rate command was added.

              The following commands were introduced or modified: channel-group (interface), debug lacp, lacp max-bundle, lacp port-priority, lacp rate, lacp system-priority, show lacp.

              PPPoX Hitless Failover

              12.2(33)SB

              The PPPoX Hitless Failover feature allows a port channel to remain in the LINK_UP state during a link switchover. In PPPoEoE, PPPoEoQinQ, and PPPoVLAN sessions, both the active and standby links assume the same configured elements after a switchover; the sessions are not forced to reestablish.

              This feature uses no new or modified commands.

              SSO - LACP

              12.2(33)SB

              The SSO - LACP feature supports stateful switchover (SSO), In Service Software Upgrade (ISSU), Cisco nonstop forwarding (NSF), and nonstop routing (NSR) on Gigabit EtherChannel bundles.

              This feature uses no new or modified commands.