Specifications

Reference Guide
2-11
Applications Data Modules and Applications
incorporates a built-in V.14 Async-to-sync converter to avoid over-sampling and
consequently saves bandwidth. Asynchronous data circuits are converted to synchronous
mode by the SRU card prior to multiplexing onto a WAN aggregate.
Subrate data ports are multiplexed into industry standard DSO formats. The user may specify
the format of the DSO that the data port is assigned to. The choices are: (1) DSO-A which
allows only one data port to be mapped into the DSO and (2) DSO-B which allows multiple
data ports from multiple SRU cards in the system to be mapped into the same DSO time slot.
If the DSO-B format is selected, then the user can specify the type of DSO-B format required
(b-5, b-10 and b-20) and the sub-rate position that the data port will occupy within the DSO-B
frame.
In b-5 mode, the DSO is divided into five sub-rate positions, each of which are occupied by a
data port operating at 9.6 Kbps, 4.8 Kbps, or 2.4 Kbps. Additionally, one or two 19.2 Kbps
circuits are supported in b-5 mode. Each would occupy two of the five sub-rate positions.
Additionally, data circuits running at 28.8 Kbps or 38.4 Kbps are supported in b-5 mode and
will occupy three or four of the five available sub-rate positions.
In b-10 mode, the DSO is divided into ten sub-rate positions, each of which are occupied by
a data port operation at 4.8 Kbps or 2.4 Kbps.
In b-20 mode, the DSO is divided into 20 sub-rate positions, each of which are occupied by a
data port operating at 2.4 Kbps.
In the application shown in Figure 2-5, the IAD with the SRU card (on the right hand side)
can either send each sub-rate on a separate DS0 (DSO-A format) or groom multiple subrate
channels into a single DS0 (one of the DSO-B formats).
Figure 2-5. IAD with SRU Card Application
The SRU card also supports X.50 division 3, an ITU (CCITT) standard for sub-rate
multiplexing. The maximum bandwidth of the SRU card is 115.2Kbps. The SRU card
provides the ability for software configurable delay optimization. If delay optimization is used
on all 10 ports, the maximum bandwidth available will be 76.8Kbps. Software-initiated
diagnostics supported on the SRU card is the same as on the HSU card.
Local
DTE
Remote
DTE
OCU-DP
CSU/DSU
RS232
V.35
T1 carrier
Network
Remote
DTE
Remote
DTE
S
y
nchronous/As
y
nchronous
DTE.
(
300 bps - 38.4 Kbps
)
Remote
DTE
IAD
IAD w/ SRU