User's Manual

www.vyyo.com
Configuration Overview – p. 22
Your System Engineer must develop a detailed system plan that accounts
for each of these variables. This plan must include the assignments of
downstream frequencies, modulations (and other RF parameters) and
upstream channel IDs assigned to the various modems deployed in the
network. If the modems are to be used with E1/ T1 connections, all related
parameters, especially QoS (Quality of Service, also referred to as Class of
Service) parameters, also need to be defined (these are discussed later in
this document.)
NOTE: The methods to define these factors are unique
to each customer and are outside the scope of this
document. They are part of the site preparation and pre-
planning, including any “overbooking” scheme that may
be desired. Please consult your Vyyo representative or
system integrator for assistance.
The Downstream and Upstream frequencies, modulations and bandwidths
MUST be pre-determined in order to proceed with the configuration of the
XMTS and the modems. Each modem must be assigned to a specific XMTS
Upstream Channel (the upstream channel is referenced by its Channel ID
which identifies the physical port.) The Upstream channel must be
configured for a specific frequency, modulation and bandwidth or symbol
rate.
NOTE: The XMTS must be configured to use the correct
Upstream and Downstream parameters. This is done
using the Vyyo Configuration tool.
It also recommended that each modem is assigned to a particular
Downstream channel (or set of channels.) The modem can use Downstream
channel discovery, however; it is typically not used since it takes much
longer to discover the correct frequencies.
Using pre-determined frequencies also allows greater control over the RF
frequency assignments and can distribute network bandwidth more
efficiently. A range of frequencies can be defined in the modem
configuration file to cover all customer assigned bands and to minimize
future re-configuration.
NOTE: The modem’s Downstream ferequency is preset
at the factory but may be changed on the modem by
using a direct Telnet connection. See Section 5.4 Setting
the Modem’s Downstream Frequency for details.
2.3 DOCSIS Layer
The most important items that must match are:
The XMTS Downstream Frequency and the modem Downstream Frequency
The XMTS Upstream Channel ID and the modem Upstream Channel ID (their
associated parameters must also match.)