Reference Guide
IMACS System Release 5.1.9
6-11
Interface Card
Interface Card User Screens and Settings
6.3.1.2
Selecting the System Timing Clocks
Table 6-3 lists the Interface Card Main Screen configuration options, along with the possible
and default values. In this screen, you must specify a primary and secondary timing source
(clock) for the Integrated Access System. These settings are described in the following
paragraphs.
Table 6-3. Interface Card Setting Options and Defaults
PRIMARY CLOCK
The primary clock provides all internal timing for the system. You can select a network clock
source or the system’s internal crystal oscillator.
A network clock is the best Primary Clock source. To select this source, set the Primary Clock
field to
wan
, and then specify the WAN link to which the clock source is connected (for
example,
w1-1
for T1 or E1 link 1 on the WAN card in chassis slot W1). The WAN clock
source will be either 1.544 or 2.048 Mbps (T1 or E1 link). This clock must be accurate to
within ±50 parts per million (50 x 10
-6
).
Select
int
to have the system generate a clock from its own internal crystal oscillator. The
stability of this Stratum 4 clock is ±25 parts per million (25 x 10
-6
). If you use the system’s
internal crystal oscillator as a clock source, all other devices attached to the network should
also derive their timing from it.
Select
serv
to use a primary clock derived from an ATM server card in the system. If you
choose this setting, also specify the associated card slot (
P1, P2, or P3
). If you select a slot
that contains any other type of server card, the message CARD CANNOT BE SELECTED
appears.
Parameter
User Options
Default
PRIMARY CLOCK
int serv(P1, P2, P3) wan(w1-1, w1-2, w2-1,
w2-2, w3-1, w3-2, w4-1,w4-2)
user(U1, U2, U3, U4, U5, U6, U7, U8)
int
EXT RATE
n/a
n/a
EXT FORMAT
n/a
n/a
EXT FRAME
n/a
n/a
SECONDARY CLK
int serv(P1, P2, P3) wan(w1-1, w1-2, w2-1,
w2-2, w3-1, w3-2, w4-1,w4-2)
user(U1, U2, U3, U4, U5, U6, U7, U8)
int
EXT RATE
n/a
n/a
EXT FORMAT
n/a
n/a
EXT FRAME
n/a
n/a
CURRENT CLK
cannot edit this field
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