PM8621 datasheet(48/184 Pages) PMC

48 / 184 page

NSE-8G™ Standard Product Data Sheet

Preliminary

Proprietary and Confidential to PMC-Sierra, Inc., and for its Customers’ Internal Use

Document ID: PMC-2010850, Issue 1

Figure 9 Character Alignment State Machine

out-of-

character-

alignment

in-

character-

alignment

5-in-15 LCVs

Found C1FP Character

9.3.5

Frame Alignment

Frame alignment locates SBI or TelecomBus frame and multiframe boundaries in the incoming

8B/10B data stream. The frame alignment state machine may be in one of two states, in-frame-

alignment state and out-of-frame-alignment state. Each SBI336S frame is 125 µS in duration.

In SBI mode: Encoded over the SBI336S frame alignment is SBI336S multiframe alignment

which is every four SBI336S frames or 500 µS. When carrying DS0 traffic in synchronous mode,

signaling multiframe alignment is also necessary and is also encoded over SBI336S alignment.

Signaling multiframe alignment is every 24 frames for T1 links and every 16 frames for E1 links,

therefore signaling multiframe alignment covering both T1 and E1 multiframe alignment is every

48 SBI336S frames or 6ms. Therefore C1FP characters are sent every four or every 48 frames.

In TelecomBus mode: Encoded over the serial link is the tributary multiframe alignment which is

every 4 frames or 500 µS. Multiframe alignment is required so that a downstream device can

extract the T1 or E1 data from the tributary. The multiframe information is preserved by only

sending out C1FP characters every four frames.

PM8621 Datasheet(PDF) 48 Page - PMC-Sierra, Inc