Description

In a Junos Subscriber Management (JSM) scenario, when the dynamic-configuration session delete session-id xxx command is executed to remove a subscriber from the session database (SDB), the subscriber count in the show subscribers summary port output is seen as not matching with the count in the show subscribers summary all output.

The article demonstrates this behavior and outlines ways to recover from the issue.

Caution: dynamic-configuration session delete session-id xxx is a hidden command that must be executed for troubleshooting only under JTAC's supervision and advice to avoid such unexpected behavior and service impact.

 

Symptoms

On forceful removal of a session by using the dynamic-configuration session delete session-id xxx hidden command, the summary port counter does not get updated accordingly. Snippets of the output of the show subscribers summary port and show subscribers summary all commands are shown here to indicate the mismatch. 

user@MX480> show subscribers summary
 
Subscribers by State
   Active: 100
   Total: 100
 
Subscribers by Client Type
   DHCP: 100  <<<<<
   Total: 100
 
user@MX480> show subscribers summary port
 
Interface           Count
irb                 100                <<<<<<  
 
Total Subscribers: 100 
 
user@MX480> show subscribers id 165 
Interface             IP Address/VLAN ID                      User Name                      LS:RI
irb.0                 21.0.0.125                              testing@dhcp              default:default     

 

user@MX480> dynamic-configuration session delete session-id 165
Succeed to delete with session id 165
 
user@MX480> show subscribers id 165 extensive                     
Total subscribers: 0, Active Subscribers: 0
 
user@MX480> show subscribers summary port
 
Interface           Count
irb                 100                <<<< This does not get updated.
 
Total Subscribers: 100
 
user@MX480> show subscribers summary
 
Subscribers by State
   Active: 99
   Total: 99
 
Subscribers by Client Type
   DHCP: 99  <<<<<   This gets updated.
   Total: 99

 

Solution

The counter mismatch is seen to be the side effect of clearing sessions forcefully and is an expected behavior.

 

For recovery with minimal impact, perform the following steps:

Standalone mode

  1. Reboot the backup Routing Engine (RE).

  2. Perform graceful Routing Engine switchover (GRES).

  3. Reboot the previous primary RE (this will be done automatically if Tomcat is enabled).

VC mode

  1. Perform VC-B local switchover. The new VC-Bm will function normally. The previous VC-Bm will be rebooted automatically and recovered.

  2. Perform VC global switchover. The previous VC-Mm will be rebooted automatically and recovered.

 

Note: A complete system reboot will recover from this issue as well but this would come with service impact.

 

Modification History

2020-02-24: minor non-technical edits.