Troubleshooting an Unsuccessful Stack Build

If you are unable to build a stack (for example, the show stack command does not display any members), perform the following steps.

  1. Enter the show running-config command on each unit to make sure the configuration contains “stack enable.” If it does not, enter the stack enable command on the unit. Before a stack is formed, you can still access the console port on each device. Once a stack is successfully formed, you are redirected to the active controller.
    Note: If you are building a stack using stack interactive-setup, you do not have to enter the stack enable command on each unit.
  2. Check that all of your stacking port connections are secure and working properly. Enter show interfaces stack on each device to confirm that the stacking port links are up and the ports are in the forward state. 
    device# show interfaces stack
Port  Link  State    Dupl Speed  Trunk   Tag  P MAC    Name
1/2/1 Up    Forward  Full 10G    None    No   1 0000.00eb.a902
1/2/2 Up    Forward  Full 10G    None    No   1 0000.00eb.a904
    Note: When you use stack interactive-setup or stack zero-touch provisioning, data ports can be in the BLOCKING state if Spanning Tree Protocol is configured. However, stack interactive-setup probe packets can traverse blocked ports.
  3. Confirm that all of the devices are running the same software image.
  4. Use the show log command to display any IPC version mismatch messages. These messages appear in one minute when receiving mismatched probe packets, and then once every 10 minutes.
  5. Use the show stack ipc command to see if any traffic has been sent or received. Enter clear stack ipc to clear the traffic statistics and then enter show stack ipc again so you can easily see differences in traffic flow. 
    device# show stack ipc
V80, G4, src=748e.f8f9.6300, max_pkt_size=10264, delay_buf=10264
Recv: SkP0: 13788, P1: 16488, sum: 30276, since t=3028.1 ago
Message types have callbacks:
Send message types:
    [1]=12422,        [5]=12600,        [6]=3,            [7]=1145,
    [9]=875,          [13]=294,         [22]=17,          [24]=644,
    [28]=41,          [31]=2651,        [40]=15,          [60]=4,
    [77]=188,
Recv message types:
    [1]= 0:4609, 1:6737,     [5]= 0:6106, 1:6459,     [6]= 0:1, 1:2,
    [7]= 0:566, 1:579,       [9]= 0:1413, 1:1597,     [13]= 0:773, 1:789,
    [23]= 0:319, 1:325,      [34]= 0:1,

Statistics:
    send pkt num          :     30890,    recv pkt num          :     30276,
    send msg num          :     30890,    recv msg num          :     30276,
    send frag pkt num     :         0,    recv frag pkt num     :         0,
    pkt buf alloc         :     30897,                          :         0,
    send_delay_msg        :         0,    send_delay_pkt        :         0,
    fwd_stby_msg          :         0,    fwd_stby_pkt          :         0,

    Reliable-mail        send  success  receive   duplic  T (us)
    target ID               2        2        0        0    82226
    target MAC              0        0        0        0    82226
    unrel target ID         5                 0
    unrel target MAC        4                 0
There is 0 current jumbo IPC session

Possible errors:

    If the "Send message types" field is empty, stack enable has not been configured. If the number of "Recv IPC packets" increases, but there are no "Recv message types," then the packets are being dropped for various reasons, including the wrong IPC version, or a checksum error. The "Possible errors" field lists reasons for packet loss.

    Note: A small "***state not ready" count is normal, but if it continues to increase, a problem is indicated.
  6. If the results of a show stack command show other stack members, but lists them as non-operational, this could be due to an image mismatch, or a configuration mismatch. In the event of an image mismatch, you can download the correct images to the entire stack from the active controller.
    Note: If your intended stacking ports are connected in a ring topology, they will not all appear to be in the forwarding state because of Spanning Tree Protocol, but stack interactive-setup can still build the stack.
  7. Check to be sure you do not have any stacking to non-stacking connections. All platforms use proprietary link negotiation to detect whether a stacking port's neighbors are also stacking ports. The platforms then convert both sides from IEEE mode (used in data ports) to HiGig mode (used in internal ports). Under stable conditions, both ends of a stacking link are converted to HiGig mode. If a stacking port is UP but in IEEE mode, its neighbor is not a stacking port. Enter the show stack stack-ports command to check if any stacking port is UP but in IEEE mode. The following example shows that U3 ports 3/2/1 to 3/2/3 are UP and in IEEE mode as indicated by the up* mark. 
    device(config-unit-3)# show stack stack-ports
                 standby      active
     +---+        +---+        +---+
  2/1| 3 |2/4==2/4| 1 |2/1==2/1| 2 |
     +---+        +---+        +---+
 
U#  Stack-port1                                            Stack-port2
1   up 1/2/1 to 1/2/3                                      up 1/2/4 to 1/2/6
    up ports: 1/2/1, 1/2/2, 1/2/3
    up ports: 1/2/4, 1/2/5, 1/2/6
 
2   up 2/2/1 to 2/2/3                                      none
    up ports: 2/2/1, 2/2/2, 2/2/3
    up ports: 1/2/4, 1/2/5, 1/2/6
 
3   up* 3/2/1 to 3/2/3                                     up 3/2/4 to 3/2/6
    up ports: 3/2/1, 3/2/2, 3/2/3
    up ports: 3/2/4, 3/2/5, 3/2/6
 
Note: *: Port is up in IEEE mode, not in HiGig mode.
Parent topic: ICX Stack Troubleshooting