STANDARD PRODUCT
PM8315 TEMUX
DATASHEET
PMC-1981125
ISSUE 7
HIGH DENSITY T1/E1 FRAMER WITH
INTEGRATED VT/TU MAPPER AND M13 MUX
octet unused. Both these rate adjustments are indicated by the SBI control
signals.
Transparent VTs (TVTs) can float in the SBI structure in two ways. The first
method uses valid V1 and V2 pointers to indicate positive and negative pointer
justifications. The second methods uses the SBI signals SDV5, SAV5, SDPL and
SAPL to indicate rate adjustments. In the DROP bus the TEMUX will always
provide both valid pointers with valid SDV5 and SDPL signals. On the SBI Add
Bus the TEMUX needs to be configured on a per tributary basis for either
transparent VT mode. Transparent VT operation is configured on a per tributary
basis via the ETVT and ETVTPTRDIS bits in the TTMP Tributary control
registers. Note that the SC1FPEN bit in Register 1209H (SONET/SDH Master
DS3 Clock Generation Control) must be set appropriately for TVT mode.
On the DROP BUS the TEMUX is timing master as determined by the arrival rate
of data over the SBI.
On the ADD BUS the TEMUX can be either the timing master or the timing slave.
When the TEMUX is the timing slave it receives its transmit timing information
from the arrival rate of data across the SBI ADD bus. When the TEMUX is the
timing master it signals devices on the SBI ADD bus to speed up or slow down
with the justification request signal, SAJUST_REQ. The TEMUX as timing
master indicates a speedup request to a Link Layer SBI device by asserting the
justification request signal high during the V3 or H3 octet. When this is detected
by the Link Layer it will speed up the channel by inserting extra data in the next
V3 or H3 octet. The TEMUX indicates a slowdown request to the Link Layer by
asserting the justification request signal high during the octet after the V3 or H3
octet. When detected by the Link Layer it will retard the channel by leaving the
octet following the next V3 or H3 octet unused. Both advance and retard rate
adjustments take place in the frame or multi-frame following the justification
request.
SBI Link Rate Information
The TEMUX SBI bus provides a method for carrying link rate information
between devices. This is optional on a per channel basis. Two methods are
specified, one for T1 and E1 channels and the second for DS3 channels. Link
rate information is not available for TVTs. These methods use the reference
19.44MHz SBI clock and the SC1FP frame synchronization signal to measure
channel clock ticks and clock phase for transport across the bus.
The T1 and E1 method allows for a count of the number of T1 or E1 rising clock
edges between 2 KHz SC1FP frame pulses. This count is encoded in
ClkRate[1:0] to indicate that the nominal number of clocks, one more than
nominal or one less than nominal should be generated during the SC1FP period.
PROPRIETARY AND CONFIDENTIAL
215
PMC [ PMC-SIERRA, INC ]
