© 2006 Cisco Systems, Inc. All rights reserved. CVOICE v5.01-1 Introduction to VoIP Calculating Bandwidth Requirements. - презентация

1 © 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Introduction to VoIP Calculating Bandwidth Requirements

2 © 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Outline Overview Codec Bandwidths Impact of Voice Samples and Packet Size on Bandwidth Data Link Overhead Security and Tunneling Overhead Calculating the Total Bandwidth for a VoIP Call Effects of VAD on Bandwidth Summary Lesson Self-Check

3 © 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Bandwidth Implications of Codec

4 © 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Impact of Voice Samples

5 © 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Data-Link Overhead Ethernet II –18 bytes of overhead MLP –6 bytes of overhead Frame Relay –6 bytes of overhead

6 © 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Security and Tunneling Overhead IPSec –50 to 57 bytes L2TP/GRE –24 bytes MLPPP –6 bytes MPLS –4 bytes

7 © 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Total Bandwidth Required CodecCodec SpeedSample SizeFrame RelayFrame Relay with CRTP Ethernet Bits per Second Bytes Bits per Second G.71164, ,26766,13379,467 G.71164, ,40067,20087,200 G.726r3232, ,26734,13347,467 G.726r3232, ,40035,20055,200 G726r2424, ,80026,40041,400 G.726r2424, ,40027,20047,200 G.726r1616, ,20017,60027,600 G.726r1616, ,40019,20039,200 G.72816, ,20017,60027,600 G.72816, ,40019,20039,200 G , ,600 G ,40011,20031,200 G.723r , ,913 G.723r , ,525 G.723r , ,985 G.723r , ,670

8 © 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Effect of VAD

9 © 2006 Cisco Systems, Inc. All rights reserved. CVOICE v Summary Different codecs have different bandwidth requirements. Voice sample size affects the bandwidth that is required. Overhead in Layer 2 protocols affects the bandwidth used. Security and tunneling adds significant overhead. Codec, Layer 2 protocol, sample size, and VAD must all be used when calculating VoIP bandwidth. VAD may lower bandwidth use up to 35 percent.

10 © 2006 Cisco Systems, Inc. All rights reserved. CVOICE v