Specifications

6-10
Reference Guide
Model No.
Running Head
Interface Card User Screens and Settings Interface Card
Table 6-3. Interface Card Option Settings and Defaults
PRIMARY CLOCK
The primary clock provides all internal timing for the system. You can select a network clock
source, 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.
Select
user
for a primary clock from a BRI card in the system. If you select
user
, also specify
the chassis slot location of the desired card (
U1 to U8
), followed by the card port from which
the clock will be provided (
u1-1 through u8-8
) as required. If you select a chassis slot that
contains any other type of user card, the message CARD CANNOT BE SELECTED appears.
If your system has an INF-E card, AND if external synchronization clocks are connected to
its SYNC jack, select either
ext1
or
ext2
. The options
ext1
and
ext2
are used when the primary
clock is derived from an external timing source. External timing sources are provided by the
user and are connected through the wire-wrap terminals of the 20186 external timing sync
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 ---