Juniper Networks G10 CMTS manual Ideal HFC Plant Configuration Issues

Ideal HFC Plant Configuration Issues

•Ideal HFC Plant Configuration Issues

•
•	This section provides a list of potential HFC plant issues and the procedures to resolve them.
•	The troubleshooting procedures in this section assume that the HFC plant is ideal and not
•	contributing to issues associated with the cable modems.
•
•	“HFC Plant Related Issues” on page 156 addresses issues associated with problems in the
•	HFC plant.
•
•	This section includes the following topics:
•
•	! Cable Modem Cannot Successfully Range on page 150
•
•	! Cable Modem Cannot Establish IP Connectivity on page 151
•
•	! Cable Modem Cannot Successfully Register on page 151
•
•	! Cable Modem Throughput is Slow on page 152
•
•	! Cable Modem is Dropped on page 156
•
•

•Cable Modem Cannot Successfully Range

•
•	If a cable modem cannot successfully range, the cause might be one or more of the following:
•
•	! The downstream and upstream interface and port mapping are not properly aligned
•
	with the forward and return path topology of the HFC plant. For example, suppose a
•
	cable modem resides in cable interface 0 (MAC domain 0), which contains downstream
•
	interface 0 and upstream interfaces 0 and 1. Also, suppose the forward and return paths
•
	are connected to downstream port 0 and upstream port 0 of an HFC Connector Module
•
	or SIM. If you manually reconfigured the CMTS so that upstream interface 0 is moved to
•
	upstream port 1, but the interface still resides in cable interface 0, when upstream
•
	interface 0 is enabled, the CMTS will be expecting the cable modem to transmit on
•
	port 1, but the cable modem will be transmitting its ranging requests on port 0.
•
•	! The upstream interface on which the cable modem resides is not enabled.
•
•	A high IM value in the flap list can be an indication of ranging issues.
•
•	The local event log might contain events that explain why a cable modem has been
•
	de-ranged. Issue the show log cable command to see the local event log.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•

150 JUNOSg 3.0 G10 CMTS Hardware Guide