Aethra THE VOICE ISDN Installationsanleitung PDF herunterladen (Seite 19)

4.4.3 SHDSL interface

The SHDSL network interface complies with the ETSI TS 101 524 standard. StarVoice

supports line rates from 192 to 2304 Kbps (3 to 36 DS0 channels).

The management (OAM) functions over EOC channels described in TS 101 524 are

available; in particular, the discovery, inventory, configuration, loopback, status

interrogation and power back-off functions are implemented.

StarVoice supports management of the characteristics associated with ATM transportation

by means of the ATM Status Cell Request and Response Interrogation Procedures.

4.4.4 ATM Quality of Service (QoS)

The ATM QoS applicable to BLES are Constant Bit Rate (CBR) and Variable Bit Rate-real

time (VBR-rt), which guarantee suitable delay limit of ATM cell transfer.

VBR-rt optimized the band used in case of non-deterministic traffic, such as voice packet

voice, where the band used depends on the number of active channels, coding law and

current voice activity.

As regards data traffic, the UBR, UBR+ and VBR-nrt QoS are supported.

4.4.5 ATM Adaptation Layers

StarVoice uses ATM Adaptation Layer 2 (AAL2) to transport voice and POTS/ISDN line

signaling. AAL2 is used to:

multiplex a number of channels for every ATM VCC; ⇒

⇒

use a segmentation method that allows to insert voice packets or voice packets

fragments in ATM cell payload for band optimization;

send “non-complete” packets when voice packets to fill ATM cell payload are not

available in order to limit segmentation delay.

AAL2 channels are identified with a Channel Identifier (CID) in the VCC that connects

StarVoice to the Voice Access Gateway (VAG). StarVoice supports the channel dynamic

allocation procedure of the ELCP (Emulated Loop Control Protocol).

4.4.6 ATM Virtual Circuit Connections

StarVoice uses one VCC for voice traffic transportation and up to 10 VCC’s for data traffic

transportation. The voice traffic transportation VCC is configured with VPI/VCI value. The

service class can be:

CBR, with associated Peak Cell Rate (PCR);

VBR-rt, with associated PCR, Sustainable Cell Rate (SCR) and Maximum Burst Size

(MBS).

Every data traffic transportation VCC is configured with VPI/VCI value. The traffic type is

UBR.

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Aethra THE VOICE ISDN Installationsanleitung Seite 19