Cisco SPA921 - - IP Phone Provisioning Manual page 27

Provisioning Cisco Small Business VoIP Devices
Provisioning Setup
Cisco Small Business IP Telephony Devices Provisioning Guide
As an alternative to HTTPS, the IP Telephony Device can resync to a configuration
profile using HTTP. In this case, a separate explicit profile encryption can be used
to protect confidential information. The IP Telephony Device supports 256-bit AES
in CBC mode to pre-encrypt individual profiles. These encrypted profiles can be
downloaded by the IP Telephony Device using HTTP without danger of
unauthorized use of confidential information in the configuration profile. This
resync mode may be useful to reduce the computational load on the provisioning
server required when using HTTPS for every resync request.
In a small deployment within a single LAN environment, it is common to rely on a
simple TFTP server for provisioning of network devices. Cisco Small Business
voice devices support TFTP for both provisioning resync and firmware upgrade
operations. TFTP is especially useful for the in-house preprovisioning of a large
number of un-provisioned devices.
Basic HTTP-based provisioning relies on the HTTP GET method for retrieving
configuration profiles. Typically, this means that a configuration file is pre-
generated for each deployed IP Telephony Device, and these files are stored
within an HTTP server directory. When the server receives the GET request, it
simply returns the file specified in the GET request header.
Alternatively, the requested URL can invoke a CGI script (still using the GET
method). In this case, the configuration profile might be generated dynamically,
perhaps by querying a customer database and producing the profile on-the-fly.
In the case of CGI handling resync requests, the IP Telephony Device also
supports the HTTP POST method as a mechanism to request the resync
configuration data. The device can be configured to convey certain status and
identification information to the server within the body of the HTTP POST request.
The server can use this information to help generate a desired response
configuration file, or store the status information for later analysis and tracking.
As part of both GET and POST requests, the IP Telephony Device automatically
includes basic identifying information in the request header, in the User-Agent
field. The supplied information conveys manufacturer, product name, current
firmware version, and product serial number.
For example, the following is the User-Agent request field from a SPA962:
User-Agent: cisco/SPA-962-2.0.5 (88012BA01234)
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