Cisco CVA122 Hardware Installation Manual page 21

Chapter 1 Product Overview
Note
14. If the DOCSIS configuration file specifies that the cable voice adapter must download another
Cisco IOS image and a Cisco IOS configuration file, the cable voice adapter uses TFTP to
download the image and configuration files into its local memory. It then installs the new Cisco IOS
image and runs the configuration file.
If Baseline Privacy Interface (BPI) encryption is configured and enabled on both the cable voice
15.
adapter and CMTS, the cable voice adapter and CMTS negotiate the appropriate
encryption/decryption parameters. After encryption is enabled, all information sent over the cable
interface is encrypted to prevent interception or modification by an unauthorized party.
Figure 1-2 illustrates the traffic flow during this process.
Figure 1-2
CMTS Interface
MAP Broadcast
DHCP Response:
Contains IP addresses
Default gateway, TOD server
TFTP server address
TFTP boot config file name
ToD Response
Registration Response
Contains Assigned SID
Cisco CVA124 registered
For more detail on the provisioning process, see the DOCSIS Radio Frequency Interface
Note
(RFI) specification (SP-RFII01-990731 or later revision).
After the Cisco CVA122/CVA122E Cable Voice Adapter goes online, it sends traffic between the
attached PCs and other CPE devices and the network (Internet, Intranet, VoIP). Because the cable voice
adapter is operating in DOCSIS bridging mode, the service provider typically provides the IP addresses
to the PCs and other CPE devices. The number of IP addresses each subscriber can obtain depends on
the services purchased from the provider.
OL-0799-02 (05/2001)
At this point the cable voice adapter is online and operational in the basic DOCSIS
bridging mode ("plug and play" mode). The next step is done only if the DOCSIS
configuration file specifies that the cable voice adapter must also download a
Cisco IOS configuration file and new Cisco IOS image.
Cisco CVA122/CVA122E Cable Voice Adapter Provisioning Overview
Contains timesharing info
Send UCD
Fail if QoS not available
or authentication failed
Cisco CVA122/CVA122E Cable Voice Adapter Description
Cisco CVA120 Series cable voice adapter
Power on
Establish synch and wait for UCD
Obtain upstream parameters
Use temporary SID
Extract slot info and upstream
channel to use
Start ranging
Transmit ranging packet with SID
DHCP request/TFTP boot request
Now in allocated slots
ToD Request
Registration Request
Send QoS Parameters
Now in allocated slots
Cisco CVA120 Series online
Cisco CVA122/CVA122E Hardware Installation Guide
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