Paradyne CPX-1000 manual Bandwidth Usage-768 kbps Sdsl Circuit

1000-A2-GN22-00 1. Voice-over-Broadband Networking

Voice is more sensitive to network latency than data, so this configuration ensures that voice traffic always has priority over data. However, this configuration also enables voice traffic to consume bandwidth when a call is in progress. Typically, few subscriber's telephone lines are simultaneously in use, so the majority of the bandwidth is usually available for data service.

For example, over a single 768 kbps symmetric DSL connection, an ICP supports up to eight simultaneous telephone calls using 2:1 compression serving a KTS with 32 extensions at a P.01 grade of service and still delivers data service at an average speed of

550 kbps (Figure 1–4).

	700
	600
				Average bandwidth available for data
	500
(K)
Bandwidth	400
	300
	200
	100
	0		Average bandwidth used by telephony
		8am	9am	10am 11am 12pm	1pm	2pm	3pm	4pm	5pm
	7am
									0202

Figure 1–4. Bandwidth Usage—768 kbps SDSL Circuit

However, many network operators have Frame Relay-based local access networks interconnected with ATM networks. The CPX can interface with the Frame Relay network through an Interworking Function (IWF) between the Frame Relay and ATM (Figure 1–3).

The IWF is an industry-standard function that either the access mux or a Frame Relay/ATM switch can execute.

In a Frame Relay network, each PVC uses an identifying Data Link Connection Identifier (DLCI). ATM PVCs, however, use a Virtual Path Identifier/Virtual Channel Identifier (VPI/VCI). The IWF maps each Frame Relay DLCI to a corresponding ATM VPI/VCI.

This association between the Frame Relay DLCI and ATM VPI/

VCI is made when provisioning PVCs.

February 2003 1-5