
Multi-Service Access Device For Channelized Interfaces
Telecom Standard Product Data Sheet
Production
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-1990823, Issue 4
616
15.3
Incoming Parallel TelecomBus
Figure 31 shows the timing of the Incoming TelecomBus interface. Timing is provided by
SYSCLK. SONET/SDH data is carried in the ID[
X
][7:0], where ‘
X
’ denotes one of the four
sections of the Incoming TelecomBus. The bytes are arranged in order of transmission in an STS-
12/STM-4 stream. Each transport/section overhead byte is labeled by Sx,y and type. Payload
bytes are labeled by Sx,y and Bn, where ‘n’ is the active offset of the byte.
A timeslot naming strategy and assignment on an ID[
X
][7:0] bus is shown in Figure 31. Within
Sx,y, the STS-3/STM-1 number is given by ‘x’ and the column number within the STS-3/STM-1
is given by ‘y’. The IPL[
X
] signal is set high to mark payload bytes and is set low at all other
bytes. The composite transport frame and payload frame signal IJ0J1[
X
] is set high with IPL[
X
]
set low to mark the J0 byte of a transport frame. IJ0J1[
X
] is set high with IPL[
X
] also set high to
mark the J1 byte of all the streams within ID[
X
][7:0].
High order streams in AIS alarm are indicated by the IPAIS[
X
] signal when the RHPP is disabled
(If the RHPP is enabled, then an AIS-P condition detected from the H1/H2 pointers is the source
of an AIS alarm). Assertion of the AIS alarm will cause the cell delineation blocks to lose
alignment. If the RHPP is enabled, garbled received packets may leak through and FCS, Min
Length and Max Length errors will be reported, so it is recommended that on receiveing a PAISI,
PLOPI, PAISCI or PLOPCI interrupt that those channels in this errored state be disabled
(CHx_DIS in the RCAS). The ICMP signal selects the active connection memory page in the
Ingress Working Time-slot Interchange (IWTI) block. It is only valid at the J0 byte position and
is ignored at all other positions within the transport frame. The J0 byte position on all four buses
must be aligned.
In Figure 31, timeslots numbers S1,x, S2,y, and S4,z are configured as STS-1/STM-0 operation.
Timeslot number S3,n is configured for STS-3c/STM-1 operation. Stream S1,1 (STM-1 #1, AU3
#1) is shown to have an active offset of 522 by the high level on IPL[
X
] and IJ0J1[
X
] at byte
S1,1/B522. Stream S2,1 (STM-1 #2, AU3 #1) is shown to be in high-order path AIS (IPAIS[
X
]
set high at bytes S2,1/Z0, S2,1/B522, S2,1/H3 and S2,1/B0). STM-1 #3 is a configured in AU4
mode and is shown to undergo a negative pointer justification event, changing its active offset
from 0 to 782. This is shown by IJ0J1[
X
] being set high at byte S3,1/H3 and IPL[
X
] being set
high at bytes S3,1/H3, S3,2/H3 and S3,3/H3.
For the case where an STS-48c/STM-16c is carried on the four buses
ID[4:1][7:0], the J0
indication is expected on all four buses (IJ0J1[4:1] = 1 and IPL[4:1] = 0) at the same time. The
J1 indication is expected only on the first bus (IJ0J1[1] = 1 and IPL[1] = 1, IJ0J1[4:2] = 0 and
IPL[1] = 1).
ICMP is sampled at the clock cycle where the J0 indication is given (IJ0J1[
X
] is logic 1 and
IPL[
X
] is logic 0). ICMP is used to select the incoming memory page in the IWTI when the
parallel TelecomBus is in use.
The arrangement shown in Figure 31 is for illustrative purposes only; other configurations, alarm
conditions, active offsets and justification events, etc. are possible.