Clock Hierarchy; Direction Conventions; Global Clocks - Vocality V200 User Manual

Vocality User Manual
User Manual for V200
Valid for V08_08.02 or V08_48.02
may later fail completely even though the configuration has not been changed from
one which was seen to work.

5.14.1 Clock Hierarchy

Clocking can only be set up "correctly" in the context of the clocking scheme for your
network, in which your Vocality unit may be only one part.
Each port generates clocks for its own use. Those ports need to be referenced to a
common clock. Within your Vocality unit one or two clocks, known as GC1, and where
available GC2, can be used to synchronize ports in each node. GC1 and GC2 allow two
discrete and independent clock hierarchies to be used. All nodes in the network must
then be referenced to each other. GC1 and GC2 can take a reference from a clock
received on a serial port, ISDN port or IP aggregate. Your goal is to create a "tree" of
clocks all referenced back to a single Master Clock for your network.
Figure 5-42 Clock hierarchy in your network

5.14.2 Direction Conventions

Ports can be presented as DCE or DTE. On DTE ports TXD is an output and RXD is an
input to the card. On DCE ports TXD is an input and RXD is an output from the card. The
clock identified as TXC is always associated with the data TXD and RXC is always
associated with RXD.
Figure 5-43 Clock direction conventions

5.14.3 Global Clocks

GC1, and GC2 where available, may be referenced to the RX or TX clock from any port.
This isThese are used as the stable reference source for all of the PLLs on any card in the
unit. GC1 and GC2 are entirely equivalent and interchangeable. Generally, one of them
is associated with the input data clock of the aggregate nominated as the master clock
source. This one is then used as the reference source for all ports. For almost all
circumstances only one of these clocks is needed: Choose GC1. With the exception of
the Setting clocks on the Digital Voice card example which follows, if you believe
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