Troubleshooting Layer 2—LAN switching

Ethernet link aggregation issues

Down aggregate interface

Symptom

When two devices are connected through link aggregation, the output from the display interface command indicates that an aggregate interface is down.

Common causes

The following are the common causes for this type of issue:

·     Incorrect configuration on the aggregate interface.

·     Physical link fault on the member ports.

·     Failure in sending and receiving LACP protocol packets.

Troubleshooting flow

To resolve this issue:

1.     Use the display link-aggregation verbose command to check whether the member ports are in selected state. If a port is in unselected state, use the display interface command to check whether the physical status of the member port is up and eliminate physical faults on the port.

2.     Check the local and peer aggregate interface configurations to eliminate configuration faults.

3.     Use the debugging link-aggregation lacp packet command to view the LACP interaction situation of the member ports of dynamic aggregation.

Figure 1 shows the troubleshooting flowchart.

Figure 1 Flowchart for troubleshooting down aggregate interface

 

Solution

1.     Check whether the physical connections are correct.

Verify that links are connected to the aggregate interface as planned.

If a physical connection is correct, proceed to step 2.

2.     Whether the aggregate interface is shut down manually.

Execute the display interface command to check the physical state of the aggregate interface. If it displays Administratively DOWN, the aggregate interface is manually shut down. Execute the undo shutdown command to enable the aggregate interface. If the aggregate interface has not been manually shut down, proceed to step 3.

3.     Check whether the member ports in the aggregation group are up.

Execute the display interface command to check if the member ports in the aggregation group are up. If not, follow the troubleshooting procedure for the down interface issue.

If the interface is up, proceed to step 4.

For example, the member port GigabitEthernet 1/0/6 in the Layer 2 aggregation group 1 is in unselected state. In the output from the display interface command, the physical status of GigabitEthernet 1/0/6 is DOWN, making the member port GigabitEthernet 1/0/6 unselected.

<Sysname> display link-aggregation verbose

Loadsharing Type: Shar -- Loadsharing, NonS -- Non-Loadsharing

Port Status: S -- Selected, U -- Unselected, I -- Individual

Port: A -- Auto port, M -- Management port, R -- Reference port

Flags:  A -- LACP_Activity, B -- LACP_Timeout, C -- Aggregation,

        D -- Synchronization, E -- Collecting, F -- Distributing,

        G -- Defaulted, H -- Expired

 

Aggregate Interface: Bridge-Aggregation1

Aggregation Mode: Static

Loadsharing Type: Shar

Management VLANs: None

  Port             Status  Priority Oper-Key

  GE1/0/6          U       32768    1

<Sysname> display interface GigabitEthernet 1/0/1

GigabitEthernet1/0/6

Current state: DOWN

Line protocol state: DOWN

IP packet frame type: Ethernet II, hardware address: 2a41-21c1-0100

Description: GigabitEthernet1/0/6 Interface

Bandwidth: 1000000 kbps

Loopback is not set

Unknown-speed mode, full-duplex mode

Link speed type is autonegotiation, link duplex type is force link

Flow-control is not enabled

Maximum frame length: 9216

Allow jumbo frames to pass

Broadcast max-ratio: 100%

Multicast max-ratio: 100%

Unicast max-ratio: 100%

Known-unicast max-ratio: 100%

PVID: 1

MDI type: Automdix

Port link-type: Access

 Tagged VLANs:   None

 Untagged VLANs: 1

Port priority: 2

Last link flapping: 0 hours 0 minutes 15 seconds

Last clearing of counters: Never

Current system time:2021-08-10 10:15:02

Last time when physical state changed to up:2021-08-09 18:31:43

Last time when physical state changed to down:2021-08-10 10:14:47

 Peak input rate: 0 bytes/sec, at 00-00-00 00:00:00

 Peak output rate: 0 bytes/sec, at 00-00-00 00:00:00

 Last 300 seconds input: 5000 packets/sec 5000 bytes/sec -%

 Last 300 seconds output: 5000 packets/sec 5000 bytes/sec -%

 Input (total):  5000 packets, 5000 bytes

         5000 unicasts, 5000 broadcasts, 5000 multicasts, 0 pauses

 Input (normal):  0 packets, 0 bytes

         0 unicasts, 0 broadcasts, 0 multicasts, 0 pauses

 Input:  5000 input errors, 0 runts, 0 giants, 0 throttles

         0 CRC, 0 frame, 0 overruns, 0 aborts

         5000 ignored, 0 parity errors

 Output (total): 5000 packets, 5000 bytes

         5000 unicasts, 5000 broadcasts, 5000 multicasts, 0 pauses

 Output (normal): 0 packets, 0 bytes

         0 unicasts, 0 broadcasts, 0 multicasts, 0 pauses

 Output: 5000 output errors, 0 underruns, 0 buffer failures

         5000 aborts, 0 deferred, 0 collisions, 0 late collisions

         0 lost carrier, 0 no carrier

4.     Check whether the aggregate interface is in dynamic mode.

¡     If the aggregate interface is in dynamic mode, check whether the peer aggregate interface is also in dynamic mode. Execute the display link-aggregation verbose command in any view to check the aggregation mode of the aggregate interfaces at both ends of the link and ensure that the aggregation modes at both ends are the same.

Taking the Layer 2 aggregate interface as an example, when Aggregation Mode: Dynamic is displayed, the aggregation interface is in dynamic mode:

<Sysname> display link-aggregation verbose bridge-aggregation 10

Loadsharing Type: Shar -- Loadsharing, NonS -- Non-Loadsharing

Port Status: S -- Selected, U -- Unselected, I -- Individual

Port: A -- Auto port, M -- Management port, R -- Reference port

Flags:  A -- LACP_Activity, B -- LACP_Timeout, C -- Aggregation,

        D -- Synchronization, E -- Collecting, F -- Distributing,

        G -- Defaulted, H -- Expired

 

Aggregate Interface: Bridge-Aggregation10

Creation Mode: Manual

Aggregation Mode: Dynamic

Loadsharing Type: Shar

Management VLANs: None

System ID: 0x8000, 000f-e267-6c6a

Local:

  Port                Status   Priority Index    Oper-Key               Flag

  GE1/0/6             S        32768    61       2                      {ACDEF}

  GE1/0/7             S        32768    62       2                      {ACDEF}

  GE1/0/8             S        32768    63       2                      {ACDEF}

Remote:

  Actor               Priority Index    Oper-Key SystemID               Flag

  GE1/0/6(R)          32768    111      2        0x8000, 000f-e267-57ad {ACDEF}

  GE1/0/7             32768    112      2        0x8000, 000f-e267-57ad {ACDEF}

  GE1/0/8             32768    113      2        0x8000, 000f-e267-57ad {ACDEF}

If the configuration is incorrect, change the aggregation interface of the remote end to dynamic aggregation. If the configuration is correct, execute the debugging link-aggregation lacp packet command to identify whether LACP packets are received and sent correctly.

Execute the debugging link-aggregation lacp packet command to view the Actor field in the send information and the Partner field in the receive information of the member port. If the sys-mac, key, and port-index fields are inconsistent, the LACP protocol packet transmission is abnormal. Check if the receiving or sending fiber is disconnected. If the sys-mac, key, and port-index fields are consistent, the LACP protocol packet transmission is normal, and proceed to step 5.

Enable the debugging switch for the LACP packets of the aggregation member port GigabitEthernet 1/0/6, and observe LACP packet receiving and sending on this port.

<Sysname> debugging link-aggregation lacp packet all interface ten-gigabitethernet 0/0/6

*Nov  2 15:51:21:15 2007 Sysname LAGG/7/Packet: PACKET.GigabitEthernet1/0/6.send.

 size=110, subtype =1, version=1

 Actor: type=1, len=20, sys-pri=0x8000, sys-mac=00e0-fc02-0300, key=0x1, pri=0x8000, port-index=0x2, state=0xc5

 Partner: type=2, len=20, sys-pri=0x0, sys-mac=0000-0000-0000, key=0x0, pri=0x0, port-index=0x0, state=0x32

 Collector: type=3, len=16, col-max-delay=0x0

 Terminator: type=0, len=0

*Nov  2 15:55:21:15 2007 Sysname LAGG/7/Packet: PACKET.GigabitEthernet1/0/6.receive.

size=110, subtype =1, version=1

 Actor: type=1, len=20, sys-pri=0x8000, sys-mac=00e0-fc00-0000, key=0x1, pri=0x8000, port-index=0x6, state=0xd

 Partner: type=2, len=20, sys-pri=0x8000, sys-mac=00e0-fc02-0300, key=0x1, pri=0x8000, port-index=0x2, state=0xc5

 Collector: type=3, len=16, col-max-delay=0x0

 Terminator: type=0, len=0

¡     If the aggregate interface is in static mode, proceed to step 5.

5.     Check whether the minimum number of selected ports for the aggregate interface affects the selection of member ports.

Execute the display this command in aggregate interface view. If the link-aggregation selected-port minimum command is configured, modify the minimum selected port limit to meet the selection requirement. If the number of selectable member ports are increased to the minimum number of selected member ports or a larger value, the status of these member ports will become selected, and the link state of the corresponding aggregate interface will also change to up.

If the minimum number of selected ports for the aggregation interface does not affect the selection of the member ports, proceed to step 6.

For example, the minimum number of selected ports for Layer 2 aggregate interface 1 is 2. The aggregation group of Layer 2 aggregation interface 1 has only one member port, so this member port is in unselected state.

[Sysname-Bridge-Aggregation1] display this

#

interface Bridge-Aggregation1

 link-aggregation selected-port minimum 2

#

return

[Sysname-Bridge-Aggregation1] display link-aggregation verbose

Loadsharing Type: Shar -- Loadsharing, NonS -- Non-Loadsharing

Port Status: S -- Selected, U -- Unselected, I -- Individual

Port: A -- Auto port, M -- Management port, R -- Reference port

Flags:  A -- LACP_Activity, B -- LACP_Timeout, C -- Aggregation,

        D -- Synchronization, E -- Collecting, F -- Distributing,

        G -- Defaulted, H -- Expired

 

Aggregate Interface: Bridge-Aggregation1

Aggregation Mode: Static

Loadsharing Type: Shar

Management VLANs: None

  Port             Status  Priority Oper-Key

  GE1/0/6          U       32768    1

6.     Check whether selected member ports exist in the aggregation group.

If no selected member port exists in the aggregation group, see "Unselection of aggregation member ports." If selected member ports exist in the aggregation group, proceed to step 7.

7.     If the issue persists, collect the following information and contact Technical Support:

¡     Results of each step.

¡     The configuration file, log messages, and alarm messages.

Related alarm and log messages

Alarm messages

N/A

Log messages

N/A

Unselection of aggregation member ports

Symptom

When two devices are connected via link aggregation, the member ports of the aggregation group are in unselected state and the aggregation fails.

Common causes

The following are the common causes for this type of issue:

·     Link connectivity fault.

·     The operational key and attribute configurations are inconsistent between the local end and the peer end.

·     The aggregation member port count is incorrect.

Troubleshooting flow

To resolve this issue:

1.     Check if the member ports are up and eliminate physical faults on the port.

2.     Use the debugging link-aggregation lacp packet command to view the LACP interaction on member ports of the dynamic aggregation group.

3.     Check the local and peer aggregate interface configurations to eliminate configuration faults.

Figure 2 shows the troubleshooting flowchart.

Figure 2 Flowchart for troubleshooting unselection of aggregation member ports

 

Solution

1.     Check if the physical connections are correct.

Perform a link check according to the network plan of the aggregate interface, and identify whether the physical connections are connected as planned.

If the physical connections are correct, proceed to step 2.

2.     Check whether the member ports in the aggregation group are up.

Use the display interface command to check if the member ports in the aggregation group are up. If they are not up, follow the troubleshooting procedure for the down interface issue.

If the member ports are up, proceed to step 3.

3.     Check whether the attribute configuration of the local member ports is the same as that of the aggregate interface.

a.     Execute the display link-aggregation verbose command to view the unselected member ports on the local end.

Taking a Layer 2 aggregate interface as an example, when the Status field displays U, the member port is unselected.

<Sysname> display link-aggregation verbose

Loadsharing Type: Shar -- Loadsharing, NonS -- Non-Loadsharing

Port Status: S -- Selected, U -- Unselected, I -- Individual

Port: A -- Auto port, M -- Management port, R -- Reference port

Flags:  A -- LACP_Activity, B -- LACP_Timeout, C -- Aggregation,

        D -- Synchronization, E -- Collecting, F -- Distributing,

        G -- Defaulted, H -- Expired

 

Aggregate Interface: Bridge-Aggregation1

Creation Mode: Manual

Aggregation Mode: Dynamic

Loadsharing Type: Shar

Management VLANs: None

System ID: 0x8000, 2a41-21c1-0100

Local:

  Port                Status   Priority Index    Oper-Key               Flag

  GE1/0/6(R)          S        32768    1        1                      {ACDEF}

  GE1/0/7             S        32768    2        1                      {ACDEF}

  GE1/0/8             U        32768    3        2                      {AC}

Remote:

  Actor               Priority Index    Oper-Key SystemID               Flag

  GE1/0/6             32768    1        1        0x8000, 36f6-c0aa-0200 {ACDEF}

  GE1/0/7             32768    2        1        0x8000, 36f6-c0aa-0200 {ACDEF}

  GE1/0/8             32768    3        1        0x8000, 36f6-c0aa-0200 {AC}

b.     Execute the display current-configuration interface command to check whether the attribute configuration (such as VLAN) of the unselected member port on the local end is the same as the aggregate interface. If not, modify the attribute configuration for consistent configuration.

For example, the member port GigabitEthernet 1/0/8 is in unselected state and has different attribute configuration from the reference port GigabitEthernet 1/0/6. This difference prevents the member port. You must modify the attribute configuration of the member port GigabitEthernet 1/0/8.

<Sysname> display current-configuration interface ten-gigabitethernet 0/0/6

#

interface GigabitEthernet1/0/6

 port link-mode bridge

 port link-type trunk

 port trunk permit vlan 1 to 20

 port link-aggregation group 1

#

return

<Sysname> display current-configuration interface bridge-aggregation 1

#

interface Bridge-Aggregation1

 port link-type trunk

 port trunk permit vlan 1 to 100

 link-aggregation mode dynamic

#

return

If the attribute configuration of the local member port is the same as the aggregate interface, proceed to step 4.

4.     Check whether the operational key of the member ports on the local end is the same as the reference port.

a.     Execute the display link-aggregation verbose command to view the unselected member ports on the local end.

Taking the Layer 2 aggregate interface as an example, when the Status field displays U, the member port is unselected:

<Sysname> display link-aggregation verbose

Loadsharing Type: Shar -- Loadsharing, NonS -- Non-Loadsharing

Port Status: S -- Selected, U -- Unselected, I -- Individual

Port: A -- Auto port, M -- Management port, R -- Reference port

Flags:  A -- LACP_Activity, B -- LACP_Timeout, C -- Aggregation,

        D -- Synchronization, E -- Collecting, F -- Distributing,

        G -- Defaulted, H -- Expired

 

Aggregate Interface: Bridge-Aggregation11

Creation Mode: Manual

Aggregation Mode: Dynamic

Loadsharing Type: Shar

Management VLANs: None

System ID: 0x8000, 2a41-21c1-0100

Local:

  Port                Status   Priority Index    Oper-Key               Flag

  GE1/0/6(R)          S        32768    1        1                      {ACDEF}

  GE1/0/7             S        32768    2        1                      {ACDEF}

  GE1/0/8             U        32768    3        2                      {AC}

Remote:

  Actor               Priority Index    Oper-Key SystemID               Flag

  GE1/0/6             32768    1        1        0x8000, 36f6-c0aa-0200 {ACDEF}

  GE1/0/7             32768    2        1        0x8000, 36f6-c0aa-0200 {ACDEF}

  GE1/0/8             32768    3        1        0x8000, 36f6-c0aa-0200 {AC}

b.     Execute the display current-configuration interface command to check whether the operational key of the local member port in unselected state (including the port's speed and duplex mode) is the same as the reference port. If not, modify the configuration for consistency.

For example, the operational key of the member port GigabitEthernet 1/0/8 in unselected state is different from that of the reference port GigabitEthernet 1/0/6. As a result, the member port cannot be selected and the port rate configuration must be modified.

<Sysname> display current-configuration interface ten-gigabitethernet 0/0/6

#

interface GigabitEthernet1/0/6

 port link-mode bridge

 combo enable fiber

 port link-aggregation group 11

#

return

<Sysname> display current-configuration interface gigabitethernet 1/0/3

#

interface GigabitEthernet1/0/8

 port link-mode bridge

 combo enable fiber

 speed 100

 port link-aggregation group 11

#

return

If the operational key of the local member port is the same as the reference port, proceed to step 5.

5.     Check whether the local aggregate interface is in dynamic mode.

If it is in dynamic mode, proceed to step 6. If it is in static mode, proceed to step 8.

6.     Check whether LACP packets are sent and received correctly.

Execute the debugging link-aggregation lacp packet command to check if LACP packets are sent and received correctly. Examine the Actor field in the send information and the Partner field in the receive information of the member port. If the sys-mac, key, and port-index fields are inconsistent, the LACP protocol packet transmission is abnormal. Check if the receiving or sending fiber is disconnected. If the sys-mac, key, and port-index fields are consistent, the LACP protocol packet transmission is normal, and proceed to step 7.

Enable the debugging switch for the LACP packets of the aggregation member port GigabitEthernet 1/0/6, and observe LACP packet receiving and sending on this port.

<Sysname> debugging link-aggregation lacp packet all interface ten-gigabitethernet 0/0/6

*Nov  2 15:51:21:15 2021 Sysname LAGG/7/Packet: PACKET.GigabitEthernet1/0/6.send.

 size=110, subtype =1, version=1

 Actor: type=1, len=20, sys-pri=0x8000, sys-mac=00e0-fc02-0300, key=0x1, pri=0x8000, port-index=0x2, state=0xc5

 Partner: type=2, len=20, sys-pri=0x0, sys-mac=0000-0000-0000, key=0x0, pri=0x0, port-index=0x0, state=0x32

 Collector: type=3, len=16, col-max-delay=0x0

 Terminator: type=0, len=0

*Nov  2 15:55:21:15 2021 Sysname LAGG/7/Packet: PACKET.GigabitEthernet1/0/6.receive.

size=110, subtype =1, version=1

 Actor: type=1, len=20, sys-pri=0x8000, sys-mac=00e0-fc00-0000, key=0x1, pri=0x8000, port-index=0x6, state=0xd

 Partner: type=2, len=20, sys-pri=0x8000, sys-mac=00e0-fc02-0300, key=0x1, pri=0x8000, port-index=0x2, state=0xc5

 Collector: type=3, len=16, col-max-delay=0x0

 Terminator: type=0, len=0

7.     Check whether the operational key and attribute configuration of the peer port for the local member port are the same as the peer port for the reference port.

Execute the display current-configuration interface command on the device on the peer end of the local unselected port. Check if the operational key and attribute configuration of the peer end for the unselected port are the same as those on the peer port for the reference port. If not, modify the configuraiton for consistency.

If the operational key and attribute configuration of the peer port for the local member port are the same as those of the peer port for the reference port, proceed to step 8.

8.     Check whether the number of aggregation member ports reaches the upper limit.

¡     The number of aggregation member ports reaches the upper limit.

Execute the link-aggregation selected-port maximum command in aggregate interface view to configure the maximum number of selected ports in the aggregation group. Use the display link-aggregation verbose command to check if the number of member ports in the aggregation group reaches the upper limit. If yes, the excess ports will be placed in unselected state. Selected ports are sorted in ascending order by port ID. Execute the undo port link-aggregation group command in member port view to remove undesired selected ports from the aggregation group for desired member ports to be selected.

¡     The number of aggregate member ports is below the lower limit.

Execute the link-aggregation selected-port minimum command in aggregate interface view to configure the minimum number of selected ports in the aggregation group. Execute the display link-aggregation verbose command to check whether the member ports in the aggregation group are lower than the lower limit. If they are lower than the lower limit, all member ports are in unselected state. Execute the link-aggregation selected-port minimum command to modify the minimum selected port count or add member ports to the aggregation group so that the minimum selection requirements are met.

If the number of aggregation member ports has not reached the limit of the aggregation group, proceed to step 9.

9.     If the issue persists, collect the following information and contact Technical Support:

¡     Results of each step.

¡     The configuration file, log messages, and alarm messages.

Related alarm and log messages

Alarm messages

N/A

Log messages

N/A