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Cisco uBR905 Router Hardware Installation Guide
OL-0598-01 (9/2000)
Chapter 1
Product Overview
Functional Overview
To ensure that subscribers obtain the exact services they have ordered, the Cisco uBR905 router arrives
from the Cisco factory with a unique identifier (UID) that consists of a serial number and MAC address.
These factory-assigned values are on a label at the bottom of the router; for convenience, these values
are also in a barcode label that can be easily scanned for easy entry into the service provider’s
provisioning and billing system.
Using the MAC address of the router as the key, the CMTS downloads the DOCSIS configuration file
and Cisco IOS image that will provide the services that this particular subscriber has purchased. Service
technicians at the headend typically create a number of standard configuration files to match the range
of services offered by the provider; these configuration files can be created manually or with tools
provided by Cisco Systems for this purpose.
The following sections describe the initial power on and provisioning sequence in more detail, as well
as the requirements that must be met by both the router and the CMTS before provisioning can succeed.
Initial Power On Sequence
When connected and first powered on, the Cisco uBR905 cable access router performs the following
DOCSIS-mandated procedure for automatic installation and configuration:
1.
The router boots the read-only memory (ROM) from the ROMMON partition of its Flash memory.
2.
The router performs a self-test, initializes processor hardware, and boots the main operating system
software—the Cisco IOS release image stored in Flash memory.
3.
The router acquires a temporary downstream channel by matching the clock sync signal that is
regularly sent out by the CMTS on the downstream channel.
4.
The router then waits for an Upstream Channel Descriptor (UCD) message from the CMTS and
configures itself for the upstream frequency specified in that message.
5.
The router waits for the next upstream bandwidth allocation map message (MAP). These messages
are regularly sent from the CMTS to find the next available shared request time slot. The router then
uses this time slot to send a ranging request message to the CMTS, communicating the router’s user
ID (UID, which includes its unique MAC address), using a temporary service identifier (SID) of 0
(zero) to indicate that it has not yet been allocated an upstream channel.
6.
In reply to the router’s ranging request, the CMTS sends a ranging response containing a temporary
SID to be used for the initial router configuration and bandwidth allocation. As needed, the router
adjusts its transmit power levels using the power increment value given by the CMTS in its ranging
response message.
Note
At this point, the router has established connectivity with the CMTS but is not yet
online. The next steps allocate permanent upstream and downstream frequencies,
as well the configuration required for IP network connectivity.
7.
After the next MAP message broadcast, the router uses a shared request time slot to invoke the
Dynamic Host Configuration Protocol (DHCP) to establish IP connectivity with the TCP/IP
network at the headend.
8.
The DHCP server—typically a dedicated server at the headend, but it could also be a CMTS such
as a Cisco uBR7200 series universal broadband router—sends a response containing the router’s IP
address, as well as the IP addresses for the default gateway and time of day (ToD) server. It also
sends the IP address for the authorized Trivial File Transfer Protocol (TFTP) server from which the
router should download its DOCSIS configuration file. Depending on the particular network
configuration, other information could be provided, such as the IP addresses for a syslog server or
security server.
