Vanguard Managed Solutions Vanguard 7300 Series - Manual (Page 68)

2-36 Vanguard 7300 Enclosures and Components
Vanguard 7300 Cards
Clock Timing
Timing The 7300 serial cards can be clocked Internal, External, ExtInt, and ExtLp with no
restrictions between ports or speeds up to 8,196,000bps. These timing modes are the
same as other standard Vanguard products. The recommended Timing configuration
for all applications is ExtInt on the DCE side and ExtLp on the DTE side (except for
X.21). This is required for all higher speed connections to work reliably.
T1/E1 Card The T1/E1 card has three groups of 4 ports (2 groups for an 8 port card). Each T1/E1
card can have a maximum of 3 different time bases on a single 12 port card (2 for 8
port cards), one on each of the groups.
The Time base for all four ports in each group must be the same, either from an
external source within the group, another group, another card or an internal
oscillator. You can set each port to Internal, Primary External (Prim_Ext), or
Secondary External (Sec-Ext). This setting determines whether the attached device
provides the timing or accepts timing from each port and also sets the priority of this
clock.
• There are three types of clock buses in the node, Group Clock, Card Clock
and System Clock. There are three Group Clock busses on each twelve-port
card (two for 8 port cards), one for each group of four ports. This locks the
timing of each of the four ports in a group together.
Clocked 7300 Port as DCE7300 Port as DTE
Internal Uses an internal oscillator and
provides clock on both the Trans-
mit and Receive clock lines. Uses an internal oscillator to pro-
vide clock on the External Trans-
mit Clock line. Expects a clock
supplied by the attached device
on Receive Clock line.
External Expects a clock on External
Transmit Clock line supplied by
the attached device. Uses an
internal oscillator to provide
clock on the Receive Clock line. Expects a clock supplied by the
attached device on both Transmit
and Receive Clock lines.
ExtInt Uses an internal oscillator to pro-
vide clock to the attached device
on the Receive Clock line.
Expects the attached device to
loop the Receive Clock around
and provide it on the External
Transmit Clock line. N/A
ExtLP N/A Expects the attached device to
provide a clock on Receive
Clock line and will loop this
clock around and provide it on
the External Transmit Clock line.