PM8611-BIAP PMC [PMC-Sierra, Inc], PM8611-BIAP Datasheet - Page 256

• Manufacturer Part Number: PM8611-BIAP
• Manufacturer: PMC [PMC-Sierra, Inc]

13.2
13.2.1
Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use
Document ID: PMC-2010883, Issue 2
Figure 16 “C1” Synchronization Control
Synchronized Control Setting Changes
The NSE-20G and SBS devices support dual switch control settings. These dual settings permit
one bank of settings to be operational while the other bank is updated as a result of some new
connection requests. The CMP input selects the current operational switch control settings. CMP
is sampled by the NSE-20G on the base timing pulse t. The internal blocks sample the registered
CMP value as they receive the next C1 character –at least a delay of RC1DLY. The new CMP
value is applied on the first A1 character of the following STS-12 frame. This switchover is
hitless; the control change does not disrupt the user data flow in any way. This feature is required
for the addition of arbitrary new connections, as existing connections may need to be rerouted
(see the discussion of the connection routing algorithm in this document).
The DS0-granularity switch settings RAM in organized into two control settings banks, these are
switched by the above mechanisms on C1 boundaries. The NSE also has to coordinate the
switching of the connected SBS devices (if using the In-Band link facility), so a broader
understanding of the issues is required.
To illustrate the system, the following describes actual examples:
SBS/NSE Systems with DS0 and CAS switching
When building a DS0 and CAS switching system with the SBS, SBSLITE and NSE devices the
overall timing is based on the CAS signaling multiframe on the SBI bus. In this configuration the
delay through the SBS devices is a single 125 µS SBI frame plus a few 77.76 MHz clocks and the
delay through the NSE is a few 77.76 MHz clocks. A single C1FP frame synchronization signal
is distributed around the system. Internal to the SBS and NSE devices are programmable offsets
used to account for propagation delays through the system. The key constraint is that all SBI
frames are aligned going into the NSE device.
Compatible devices are the PM8316 TEMUX™-84, PM7388 FREEDM™-336, PM389
FREEDM™-336/84, PM7341 S/UNI-IMA-84, and other future SBI336 devices.
t
0
Ingress SBI
device
t at 0 s
t
0
,
t
1
delay
(no delay t delay through
t
1
Ingress SBI device)
(1 frame delay)
Ingress SBS
125 s
delay
delay
t
2
125 s Source
t
2
NSE
SBSLITE™ Telecom Standard Product Data Sheet
t
3
delay
t
3
125 s
delay
(1 frame delay)
Egress SBS
t
4
delay
t
4
Egress SBI
device
Preliminary
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