Installation guide

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Cisco uBR7100 Series Universal Broadband Router Software Configuration Guide
OL-2238-03
Chapter 1 Overview
Operating Standards for Cisco IOS Software
• Security and authentication servers—These servers are optional for two-way installations but are
required for a telco-return installation.
DOCSIS 1.0-based CMs cannot connect to the broadband network until the following processes occur:
• The CM initializes and ranges through available frequencies until it finds the first frequency that it
can use to communicate to the CMTS—known as scanning for a downstream channel.
• The CM obtains upstream parameters and performs ranging.
• The CM goes through the DHCP server process and establishes IP connectivity, time of day (TOD,
optional), and security (optional). At this point, the CM cannot determine if it is communicating on
the correct channel.
• The CM receives a DOCSIS configuration file from the Trivial File Transfer Protocol (TFTP) server.
One of the parameters in the DOCSIS configuration file tells the CM which channel it can use.
• The CM registers with the CMTS.
• If the network supports DOCSIS baseline privacy interface (BPI) or other secure data sets,
encryption/decryption processes are initialized.
• The CM is ready for normal operations. Once initialized and operational, CMs send requests to
initiate data transmission to the CMTS.
The CMTS system administrator or customer service representative ensures appropriate databases
are updated to activate and support the new subscriber account in the provisioning, billing, or
network management systems in use for the network. Each CM or STB serial number and MAC
address is typically stored in the billing and administrative system.
Initial and station maintenance management messages are sent to maintain communications between
CMs and the CMTS. The following is a typical sequence of messages:
1. An offline CM powers up and brings up its cable interface.
2. The CM begins searching on the cable interface for an available downstream frequency.
3. The CM continues searching the downstream frequencies until it finds an active and available
frequency and locks on to that frequency.
4. The CMTS sends one or more Upstream Channel Description (UCD) messages to the CM
containing information about the upstream channel it should use.
5. The CM scans each upstream channel identified in the UCD messages, and if a usable channel is
found, it obtains the bandwidth allocation map for the channel. If no usable channel is found, the
CM attempts to lock on another downstream.
6. The CM begins its initial ranging, using a temporary identifier on the upstream, to obtain its
permanent Service ID (SID) and initial upstream frequency and power levels.
7. When ranging is successful, the CM transmits a DHCP request on the cable interface.
8. The DHCP server receives the DHCP request and replies with a DHCP reply that contains the
information appropriate for this particular CM (IP address, default gateway, ToD server address,
TFTP server address, and so forth).
9. The CM then contacts the ToD server to obtain a current timestamp. This step is optional but is
recommended because it allows the CM to timestamp its log and other messages, which can be
helpful in troubleshooting problems and managing the network.