Circuit Pack Descriptions
Issue 8.0 July 2002
7-29
Memory 7
Start-Up Memory. 7The start-up memory consists of 64 kilobytes of read-only
memory. The start-up memory contains the program that allows the processor to
load the executable code and data from the SYSCTL circuit pack into the
operating memory. This allows the processor to start up operation during a
power-up or a reset condition, or when initializing new software.
Operating Memory. 7The main operating memory consists of 4 megabytes of
DRAM. Direct memory access (DMA) allows the processor to load the executable
code and data received from the SYSCTL circuit pack (via the overhead access
local area network) into the operating memory during a power-up or reset
condition, or when initializing new software.
Nonvolatile Memory. 7The nonvolatile memory consists of 128 bytes of
electrically-erasable programmable read-only memory (EEPROM). The
nonvolatile memory is used to store information about the history of the TOHCTL
circuit pack such as the
CLEI
code and type/version information.
Interface Circuitry 7
DCC Interface. 7The DCC interface interacts with the OC-3/OC-12 (1.3 STD) circuit
packs on the Low Speed Shelf - System Controller. Up to eight LS INTFC slots
(1A through 8B) equipped with OC3/OC-12 (1.3 STD) circuit packs may be
assigned to the DCC interface. The DCC interface performs protocol processing
for layer 1 (physical) and layer 2 (data link) of the OSI 7-layer stack for the
OC-3/OC-12 section DCC. Refer to Volume I, Section 8, "Administration and
Provisioning," for more information about OC-3/OC-12 DCC channel
assignments.
In the receive direction (from the OC-3/OC-12 line), the assigned OC3/OC-12 (1.3
STD) circuit pack transmits the overhead bytes via the overhead channel to the
DCC interface. The DCC interface transmits the information to the processor for
layer 3 (network) protocol processing.
In the transmit direction (toward the OC-3/OC-12 line), the DCC interface accepts
the OC-3/OC-12 section DCC bytes from the processor and transmits the
information via the overhead channel to the assigned OC3/OC-12 (1.3 STD)
circuit pack. This information provides end-to-end communications and
maintenance.
In addition to support for OC-3 and OC-12 links configured as 0x1
unprotected—the DCC interface also supports 1+1 protection switching for OC-3
and OC-12 links.
To Next Page
Loading...
Need help?
General