OOBM and active and inactive fragments

When there are two fragments are the same size and OOBM is enabled and configured for all members of the stack, then the fragment that contains the Commander will be Active and the other fragment becomes Inactive. However, if OOBM is not enabled and configured for all members of the stack, then each fragment will be Active. To resolve this issue, OOBM must be enabled and configured.

Below are the behaviors observed with two-member stack in a chain configuration and the stacking cable is removed to simulate a failure that results in two identical size fragments:

switch# show stack
 
Stack ID         : 01002c59-e51c5bc0
 
MAC Address      : 2c59e5-1c5be3
Stack Topology   : Chain
Stack Status     : Active
Split Policy     : One-Fragment-Up
Uptime           : 0d 0h 13m
Software Version : WB.15.16.0005
 
 Mbr
 ID  Mac Address   Model                                  Pri Status
 --- ------------- -------------------------------------- --- ---------------
 1   2c59e5-1c5bc0 HPE J9726A 2920-24G Switch             128 Commander
 2   d4c9ef-a49e00 HPE J9726A 2920-24G Switch             128 Standby

switch# show stack stack-ports
  Member Stacking Port State    Peer Member Peer Port
  ------ ------------- -------- ----------- ---------
  1      1             Up       2           2
  1      2             Down     0           0
  2      1             Down     0           0
  2      2             Up       1           1

Results without OOBM configured:

From physical console of Member 1 (original stack commander):

switch# show stack
 
Stack ID         : 01002c59-e51c5bc0
 
MAC Address      : 2c59e5-1c5be3
Stack Topology   : Chain
Stack Status     : Fragment Active
Split Policy     : One-Fragment-Up
Uptime           : 0d 0h 09m
Software Version : WB.15.16.0005
 
 Mbr
 ID  Mac Address   Model                                  Pri Status
 --- ------------- -------------------------------------- --- ---------------
 1   2c59e5-1c5bc0 HPE J9726A 2920-24G Switch             128 Commander
 2   d4c9ef-a49e00 HPE J9726A 2920-24G Switch             128 Missing

From physical console of Member 2:

switch# show stack
 
Stack ID         : 01002c59-e51c5bc0
 
MAC Address      : 2c59e5-1c5be3
Stack Topology   : Chain
Stack Status     : Fragment Active
Split Policy     : One-Fragment-Up
Uptime           : 0d 0h 9m
Software Version : WB.15.16.0005
 
 Mbr
 ID  Mac Address   Model                                  Pri Status
 --- ------------- -------------------------------------- --- ---------------
 1   2c59e5-1c5bc0 HPE J9726A 2920-24G Switch             128 Missing
 2   d4c9ef-a49e00 HPE J9726A 2920-24G Switch             128 Commander
    

Note that both switches are Commanders and both Fragments remain Active.

Results with OOBM configured:

OOBM is now enabled with both oobm ports connected to the same network segment:

switch# sh oobm ip
 
  IPv4 Status    : Enabled
  IPv4 Default Gateway : 10.238.255.254
 
        |                                     Address  Interface
Member | IP Config IP Address/Prefix Length  Status   Status
------ + --------- ------------------------- -------- ---------
Global | manual    10.238.123.37/16          Active   Up
1      | manual    10.238.123.37/16          Active   Up
2      | manual    10.238.123.39/16          Active   Up


switch# show stack (from console of member 1)
 
Stack ID         : 01002c59-e51c5bc0
 
MAC Address      : 2c59e5-1c5be3
Stack Topology   : Chain
Stack Status     : Fragment Active
Split Policy     : One-Fragment-Up
Uptime           : 0d 0h 16m
Software Version : WB.15.16.0005
 
 Mbr
 ID  Mac Address   Model                                  Pri Status
 --- ------------- -------------------------------------- --- ---------------
 1   2c59e5-1c5bc0 HPE J9726A 2920-24G Switch             128 Commander
 2   d4c9ef-a49e00 HPE J9726A 2920-24G Switch             128 Missing


switch# show stack (from console of member 2)
 
Stack ID         : 01002c59-e51c5bc0
 
MAC Address      : 2c59e5-1c5be3
Stack Topology   : Chain
Stack Status     : Fragment Inactive
Split Policy     : One-Fragment-Up
Uptime           : 497d 1h 57m
Software Version : WB.15.16.0005
 
 Mbr
 ID  Mac Address   Model                                  Pri Status
 --- ------------- -------------------------------------- --- ---------------
 1   2c59e5-1c5bc0 HPE J9726A 2920-24G Switch             128 Missing
 2   d4c9ef-a49e00 HPE J9726A 2920-24G Switch             128 Commander

Note that both switches are Commanders, but that the stack fragment containing member 2 is listed as "Fragment Inactive". This is the correct behavior and why it is important that OOBM is enabled and configured for all members of the stack.