How CWMP works
CWMP uses remote procedure call (RPC) methods for bidirectional communication between CPE and
ACS. The RPC methods are encapsulated in HTTP or HTTPS.
shows the primary RPC methods used in CWMP.
Table 23 RPC methods
Autoconnect between ACS and CPE
The CPE connects to the ACS automatically after it obtains the DNS server address and basic ACS
parameters (ACS URL and authentication username and password). You can configure this information
manually on the CPE, through a DHCP server, or through the ACS.
After establishing a connection, the ACS can issue configuration and software images to the CPE. If the
connection is disconnected before a session is complete, the CPE retries the failed connection
automatically. The retry attempt continues until the connection is established again or the specified retry
limit is reached.
Depending on the configuration, the CPE can also connect to the ACS regularly or at a scheduled time
to update its information with the ACS.
ConnectionRequestURL (CPE URL)
ConnectionRequestUsername (CPE username)
ConnectionRequestPassword (CPE password)
The ACS obtains the values of parameters on the CPE.
The ACS modifies the values of parameters on the CPE.
The CPE sends an Inform message to the ACS for the following purposes:
Initiates a connection to the ACS.
Reports configuration changes to the ACS.
Periodically updates CPE settings to the ACS.
The ACS requires the CPE to download a configuration or software image file from a
specific URL for software or configuration update.
The ACS requires the CPE to upload a file to a specific URL.
The ACS reboots the CPE remotely for the CPE to complete an upgrade or recover from
an error condition.