ADTRAN 6530 - page 16

16 61225001L1-5D

Multiple Services

The NTU supports the configuration of multiple

services. These services are routed to either the

G.703/G.704 interface or the Nx64K interface. The

Nx64K interface supports a single service with

1 <= N <= 36. The G.703 interface (with G.704

framing) supports multiple services (often termed

“Stacked E1”). The G.703 interface without any

framing supports a single 2048 kBit/s service. (See

ITU-T G991.2 Annex. E.1-TPS-TC for European

2048 kbit/s digital Unstructured Leased Line

(D2048U).)

The Nx64K service and G.703 service are capable of

operating simultaneously. The total number of time

slots must be less than or equal to the maximum

number of SHDSL time slots (excluding TS0 if

structured E1 is used). The G.703 interface with

framing (G.704) runs over SHDSL in aligned mode

and supports simultaneous services using the Nx64K

port for the second service. (See ITU-T G991-2

Annex E.7 - TPS-TC for Aligned European 2048

kbit/s digital Structured Leased Line (D2048S) and

Fractional.)

The SHDSL NTU supports CRC-4 detection/

generation toward the SHDSL network (Figure 22).

The CRC-4 detection/generation can operate in the

following modes (configurable via the management

interface):

1. CRC-4 detection/generation disabled

2. CRC-4 detection/generation enabled

When less than 32 time slots are configured on the

G.703 port, the NTU bases the CRC-4 detection/

generation on filling the unused time slots with a fixed

pattern configurable via the management interface.

This CRC-4 detection/generation is also required for

multi-rate (single or simultaneous services) where less

than 31 G.704 time slots are carried over the SHDSL

line.

NOTE

All framed services operate in aligned mode.

Operation

The SHDSL NTU supports multiple rate line

operation as specified in ITU-T G.991.2. All services

described in this document operate in multiple rate

mode, with a corresponding change in maximum

payload. Unstructured E1 is supported for SHDSL

rates equal to 32 and with all G.703 time slot

assignments equal to the same G.703 service value

(1 to 31).

The G.703 interface supports operation in the

following modes that are selectable via the

management interface:

1. Framed

2. Framed pass through

3. Unframed

Figure 22. CRC-4 Detection/Generation

SHDSL Time Slots

Nx64K Service

TS0

TS1

TS2

TS3

TS4

TS5

TS6

TS7

TS8

TS9

TS10

TS11

TS12

TS13

TS14

TS15

TS16

TS17

TS18

TS19

TS20

TS21

TS22

TS23

TS24

TS25

TS26

TS27

TS28

TS29

TS30

TS31

TS32

TS33

TS34

TS35

TS0

TS1

TS2

TS3

TS4

TS5

TS6

TS7

TS8

TS9