AP Firmware updating via ZAC tool explained

ZAC (Zyxel AP Configurator) is a tool, which can be used to configure and update multiple APs at the same time. Further information regarding the tool can be found here. In this article, we describe the way the update function works with packet traces.

When we use ZAC to upgrade the firmware, we can separate the progress into three parts: Ask, Discover, Transmit.

Table of Content

1. Ask

2. Discover

3. Transmit

1. Ask

ZAC will send out ARP request to which we set in the Discovery AP Address range.

192.168.10.13 replied the ARP request.

ZAC will try to ping the AP to realize if it can be reached.

After confirming the AP can be reached, ZAC will use SNMP to get the information.

2. Discover

ZAC will send out SNMP request to the IP address which replied the ARP and ping request to get information.

While the SNMP request is responded, the AP information will be listed on the ZAC.

3. Transmit

Since ZAC is using FTP to transfer the firmware, ZAC will communicate with the AP for using FTP via TCP protocol.

While getting the ACK from the AP, ZAC will start to transfer the firmware via FTP. ZAC will pop out a window to ask the user to key in username and password of AP.

Confirm the AP username/password is correct, the firmware transmission will be started, and the connection will be interrupted automatically after finishing.

In the end, ZAC will send out SNMP to the AP to get the latest status.