Cisco Systems MC-607 manual Event Description, MC-627

Configuring Subscriber-End Broadband Access Router Features

Subscriber-End Broadband Access Router Initial Power-Up Sequence

Next, the Cisco uBR900 series performs a series of DOCSIS-mandated procedures for automatic installation and configuration. These procedures are summarized in Table 40 and in Figure 114.

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Table 40	Cable Access Router Initialization Sequences and Events
Sequence		Event	Description
1.		Scan for a downstream channel		The Cisco uBR900 series acquires a downstream
		and establish synchronization		channel by matching the clock sync signal that is
		with the CMTS.		regularly sent out by the CMTS on the downstream
				channel. The cable access router saves the last
				operational frequency in nonvolatile memory and tries
				to reacquire the saved downstream channel the next
				time a request is made.
				Note	An ideal downstream signal is one that
					synchronizes QAM symbol timing, FEC
					framing, and MPEG packetization, and
					recognizes downstream sync MAC layer
					messages.
2.		Obtain upstream channel		The cable access router waits for an upstream channel
		parameters.		descriptor (UCD) message from the CMTS and
				configures itself for the upstream frequency specified
				in that message.
3.		Start ranging for power		The cable access router waits for the next upstream
		adjustments.		bandwidth allocation map message (MAP) from the
				CMTS to find the next shared request timeslot. The
				router then sends a ranging request message on the
				next available shared request timeslot, communicating
				its UID (its unique MAC address) using a temporary
				SID of 0 (zero) to indicate it has not yet been allocated
				an upstream channel.
				In reply to the cable access router 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 cable access router has
					established connectivity with the CMTS but is
					not yet online. The next steps allocate
					“permanent” upstream and downstream
					frequencies, and the configuration required for
					IP network connectivity.
		Cisco IOS Multiservice Applications Configuration Guide

MC-627