When Junos OS enhanced subscriber management is configured for the first time on a Routing Engine (RE) that has more than 32 GB of memory, the configuration fails to commit on MX Series routers.

This article explains that when the RE has more than 32 GB memory, the enhanced subscriber management daemon runs in 64-bit mode and hence requires max-db-size to be set to be enabled successfully.

When enhanced subscriber management is configured for the first time on an RE that has more than 32 GB memory, commit fails as shown below:

[edit]
labroot@mx-re0# show system configuration-database 


[edit]
labroot@mx-re0# show | compare 
[edit]
+  system {
+      services {
+          subscriber-management {
+              enable;
+          }
+      }
+  }


[edit]
labroot@mx-re0# commit 
[edit system services subscriber-management]
  'enable'
    warning: Chassis configuration for subscriber-management has been changed. A system reboot is mandatory.  Please reboot the system NOW. Continuing without a reboot might result in unexpected system behavior.
[edit groups junos-defaults system]
  'configuration-database'
    WARNING: system configuration-database max-db-size must be set to less than or equal to 698343424 to enable subscriber-management feature set.
error: configuration check-out failed

 
labroot@mx-re0# run show version 
Hostname: mx-re0
Model: mx10003
Junos: 18.4R1.8
JUNOS OS Kernel 


[edit]
labroot@mx-re0# run show chassis routing-engine 
Routing Engine status:
  Slot 0:
    Current state                  Master
    Election priority              Master (default)
    Temperature                 35 degrees C / 95 degrees F
    CPU temperature             40 degrees C / 104 degrees F
    DRAM                      49106 MB (49152 MB installed)    <--- greater than 32 GB

When the above commit is performed, the MX router transitions from legacy subscriber management to enhanced subscriber management. By default, the enhanced subscriber management daemon (smgd) runs in 32-bit mode. However, when the RE has more than 32 GB memory, it runs in 64-bit mode. Hence, to enable enhanced subscriber management, which runs on the 64-bit smgd, it is necessary to set a value for max-db-size to support the transition from legacy subscriber management to enhanced subscriber management on all REs.

Note: It is recommended that max-db-size should be deleted post initial reboot in certain releases to support better memory management. See max-db-size (Enhanced Subscriber Management) .

To configure enhanced subscriber management for the first time on REs that has more than 32 GB memory, follow these steps:

1. Configure set network-services enhanced-ip .

2. Configure set subscriber-management enable .

3. Configure set system configuration-database max-db-size 300M (100M for MX5, MX10, MX40, MX80, and MX104) .

4. Commit. This step will recommend reloading the unit.

5. When the unit is reloaded, you can delete max-db-size as follows:

delete system configuration-database max-db-size 
commit [this step recommends reboot again]

6. Reload the unit so that enhanced subscriber management runs without the max-db-size configuration.