When subscribers observe disconnections, how to verify the cause for subscriber disconnections

PPPoE subscribers may be getting disconnected as outlined in the below show commands:
labroot@vellore-re0> show subscribers summary | refresh 30   
---(refreshed at 2024-09-18 21:43:31 PDT)---
 
Subscribers by State
   Init: 311
   Configured: 78
   Active: 2165
   Terminating: 2
   Terminated: 7
   Total: 2563
 
Subscribers by Client Type
   DHCP: 79
   PPPoE: 2484
   Total: 2563
---(refreshed at 2024-09-18 22:37:32 PDT)--- 
Subscribers by State
   Init: 282
   Configured: 77
   Active: 2149
   Terminating: 1
   Terminated: 7
   Total: 2516

Subscribers by Client Type
   DHCP: 76
   PPPoE: 2440
   Total: 2516

labroot@vellore-re0> clear pppoe statistics    
labroot@vellore-re0> show pppoe statistics | refresh 30    
---(refreshed at 2024-09-18 21:43:09 PDT)---
Active PPPoE sessions: 2467
  PacketType                       Sent         Received
    PADI                              0               27
    PADO                             22                0
    PADR                              0               19
    PADS                             19                0
    PADT                             16                3
    Service name error                0                0
    AC system error                   0                0
    Generic error                     0                0
    Malformed packets                 0                0
    Unknown packets                   0                0
---(refreshed at 2024-09-18 22:37:26 PDT)---
Active PPPoE sessions: 2429
  PacketType                       Sent         Received
    PADI                              0            36006
    PADO                          29469                0
    PADR                              0            26550
    PADS                          26550                0
    PADT                          23741             8748
    Service name error                0                0
    AC system error                   0                0
    Generic error                     0                0
    Malformed packets                 0                0
    Unknown packets                   0                0
---(*more 100%)---[abort]

The show network-access aaa terminate-code command output fields are listed in the approximate order in which they appear. It displays the count for termination, and its cause types with code values as follows:
labroot@vellore-re0> clear network-access aaa statistics terminate-code    
labroot@vellore-re0> show network-access aaa terminate-code brief | refresh 30    
---(refreshed at 2024-09-18 21:43:59 PDT)---
Terminate-code:
  RADIUS     Custom Usage-Count Type Code
  10         no     20          ppp  lcp-keepalive-failure                     
  1          no     1           ppp  lcp-peer-terminate-term-req               
---(refreshed at 2024-09-18 22:37:30 PDT)---
Terminate-code:
  RADIUS     Custom Usage-Count Type Code
  10         no     5467        ppp  lcp-keepalive-failure                     
  1          no     769         ppp  lcp-peer-terminate-term-req                                      
---(*more 100%)---[abort]

Based on the termination code and its protocol, further troubleshooting can focus on issue isolation.
For instance, since the termination codes from the above output are for PPP, our troubleshooting should concentrate on PPP and PPPoE.
In the above scenario termination code causes are as listed and the issue was isolated to the end user requesting termination:
lcp-keepalive-failure --- NAS Request
lcp-peer-terminate-term-req --- User Request
Check out the below document for more details on the cause of the PPP termination code-type:
PPP Termination Causes and Code Values

We can also enable traceoptions to track the subscriber status and the packets exchanged using session ID on a need-by-need basis.
Commands to enable authd traceoptions:
set system processes general-authentication-service traceoptions file authd
set system processes general-authentication-service traceoptions file size 100m
set system processes general-authentication-service traceoptions file files 2
set system processes general-authentication-service traceoptions flag all

Commands to enable pppoe traceoptions:
set protocols pppoe traceoptions file pppoe
set protocols pppoe traceoptions file size 100m
set protocols pppoe traceoptions file files 10
set protocols pppoe traceoptions level all
set protocols pppoe traceoptions flag all

Commands to enable ppp traceoptions:
set protocols ppp traceoptions file ppp
set protocols ppp traceoptions file size 100m
set protocols ppp traceoptions file files 10
set protocols ppp traceoptions level all
set protocols ppp traceoptions flag all

Commands to enable smgd-service traceoptions:
set system processes smg-service traceoptions file smgd
set system processes smg-service traceoptions file size 100m
set system processes smg-service traceoptions file files 10
set system processes smg-service traceoptions level all
set system processes smg-service traceoptions flag all

Commands to enable l2tp traceoptions:
set services l2tp traceoptions file l2tp_log
set services l2tp traceoptions file size 100m
set services l2tp traceoptions file files 10
set services l2tp traceoptions level all
set services l2tp traceoptions flag all

Commands to enable dhcp traceoptions:
set system processes dhcp-service traceoptions file dhcp
set system processes dhcp-service traceoptions file size 100m
set system processes dhcp-service traceoptions file files 10
set system processes dhcp-service traceoptions level all
set system processes dhcp-service traceoptions flag all

Commands to enable static-subscribers raceoptions:
set system processes static-subscribers traceoptions file static-subs-trace
set system processes static-subscribers traceoptions file size 100m
set system processes static-subscribers traceoptions file files 10
set system processes static-subscribers traceoptions level all
set system processes static-subscribers traceoptions flag all

Reference links for other protocols:
Session Termination Causes and RADIUS Termination Cause Codes
AAA Termination Causes and Code Values
DHCP Termination Causes and Code Values
VLAN Termination Causes and Code Values
L2TP Termination Causes and Code Values

2024-09-18 : Article Created

2024-11-28 : Adding traceoptions for static-subscribers