Auto-installation on SRX/J-series devices does not start when using SLARP with cisco-hdlc encapsulation

When SLARP is used for auto-installation, the SLARP address acquisition requests are sent to the remote end. The Auto-installation daemon handles these events. At times, auto-installation does not start its state machine. The following output illustrates the auto-installation status:

root@host> show system autoinstallation status Autoinstallation status:
Master state: Active
Last committed file: None
Configuration server of last committed file: None
Interface:
  Name: t3-1/0/0
  State: None

The above output means that the autod daemon is in the idle state and does not start the state machine. In this condition, the client device does not send out address acquisition requests to the remote end. Ideally, autod should enter the Address Acquisition state, when working properly:

root@host> show system autoinstallation status
Autoinstallation status:
Master state: Active
Last committed file: None
Configuration server of last committed file: None
Interface:
  Name: t3-1/0/0
  State: None
  Address acquisition:
    Protocol: SLARP Client
    Acquired address: None

This is due to the encapsulation configuration on the client:

root@host# show interfaces t3-3/0/0                      
description "WAN LINK";
keepalives interval 10;
clocking internal;
encapsulation cisco-hdlc;< This needs to be removed
t3-options {
    compatibility-mode digital-link;
    payload-scrambler;
    cbit-parity;
    fcs 32;
    feac-loop-re
}

By design, autod automatically configures the encapsulation, based on the configuration of the remote end. When the encapsulation is explicitly configured, autod moves to the idle state; as per design.

To resolve this issue, remove the encapsulation on the client and make sure that the remote end has this configuration.

Knowledge Base