Cvoice 6.0 S01 L04

Understanding Codecs, Codec Complexity, and DSP Functionality

Introducing Voice over IP

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-1

Codecs  Codecs perform encoding and decoding on a digital data stream or signal.  Codecs translate VoIP media streams into another format: A to D, D to D, or D to A.  Various codec standards define the compression rate of the voice payload.  Supported Cisco codecs include: – G.711 – G.722 – G.726 – G.728 – G.729 – G.723.1 – GSM FR – iLBC

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-2

Impact of Voice Samples and Sample Size on Bandwidth Codec

Bandwidth

Sample Size

Packets

G.711

64 kb/s

240

33

G.711

64 kb/s

160

50

G.726r32

32 kb/s

120

33

G.726r32

32 kb/s

80

50

G.726r24

24 kb/s

80

25

G.726r24

24 kb/s

60

33

G.726r16

16 kb/s

80

25

G.726r16

16 kb/s

40

50

G.728

16 kb/s

80

13

G.728

16 kb/s

40

25

G.729

8 kb/s

40

25

G.729

8 kb/s

20

50

G.723r63

6.3 kb/s

48

16

G.723r63

6.3 kb/s

24

33

G.723r53

5.3 kb/s

40

17

G.723r53

5.3 kb/s

20

33

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-3

Data-Link Overhead  Ethernet II: 18 bytes of overhead  PPP: 6 bytes of overhead  FRF.12 Layer 2 header: 6 bytes of overhead  MP: 6 bytes of overhead

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-4

Security and Tunneling Overhead  IPsec: 50 to 57 bytes  L2TP or GRE: 24 bytes  MLP: 6 bytes  MPLS: 4 bytes

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-5

Calculating the Total Bandwidth for a VoIP Call Codec Speed

Sample Size

Frame Relay

Frame Relay with cRTP

Ethernet

Bits per Second

Bytes

Bits per Second

Bits per Second

Bits per Second

G.711

64,000

240

76,267

66,133

79,467

G.711

64,000

160

82,400

67,200

87,200

G.726r32

32,000

120

44,267

34,133

47,467

G.726r32

32,000

80

50,400

35,200

55,200

G726r24

24,000

80

37,800

26,400

41,400

G.726r24

24,000

60

42,400

27,200

47,200

G.726r16

16,000

80

25,200

17,600

27,600

G.726r16

16,000

40

34,400

19,200

39,200

G.728

16,000

80

25,200

17,600

27,600

G.728

16,000

40

34,400

19,200

39,200

G.729

8000

40

17,200

9600

19,600

G.729

8000

20

26,400

11,200

31,200

G.723r63

6300

48

12,338

7350

13,913

G.723r63

6300

24

18,375

8400

21,525

G.723r53

5300

40

11,395

6360

12,985

G.723r53

5300

20

17,490

7420

20,670

Codec

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-6

Effects of VAD Codec Speed

Sample Size

Frame Relay

Frame Relay with VAD

G.711

64,000

240

76,267

49,573

G.711

64,000

160

82,400

53,560

G.726r32

32,000

120

44,267

28,773

G.726r32

32,000

80

50,400

32,760

G726r24

24,000

80

37,800

24,570

G.726r24

24,000

60

42,400

27,560

G.726r16

16,000

80

25,200

16,380

G.726r16

16,000

40

34,400

22,360

G.728

16,000

80

25,200

16,380

G.728

16,000

40

34,400

22,360

G.729

8000

40

17,200

11,180

G.729

8000

20

26,400

17,160

G.723r63

6300

48

12,338

8019

G.723r63

6300

24

18,375

11,944

G.723r53

5300

40

11,395

7407

G.723r53

5300

20

17,490

11,369

Codec

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-7

Digital Signal Processors Media resource: A software-based or hardware-based entity that performs media-processing functions on the data streams to which it is connected.  Transcoding: The conversion from one codec to another.  Voice termination: The digitization and packetization of an analog signal on a TDM interface.  MTP: Two supported types on Cisco IOS routers: – Software MTPs – Hardware MTPs  Conferencing: Network-based conference bridge is required to facilitate multiparty conferences in VoIP network.

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-8

Media Resource Deployment Example San Jose

Chicago Transcoding or conferencing

IP WAN

Conferencing

G.729

IVR G.711 Router1

Phone1-1 2001

Phone1-2 2002

© 2008 Cisco Systems, Inc. All rights reserved.

Router2

PSTN

Phone2-1 3001

Phone2-2 3002

CVOICE v6.0—1-9

Codec Complexity Medium Complexity (Four calls per DSP)

High Complexity (Two calls Per DSP)

G.711 (a-law and mu-law)

G.728

G.726 (all versions)

G.723 (all versions)

G.729A, G.729AB

G.729, G.729B

Fax Relay

Fax Relay

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-10

Configuring Codec Complexity C549 router(config)# voice-card 1 router(config-voicecard)# codec complexity ? high

Set codec complexity high. High complexity, lower call density.

medium

Set codec complexity medium. Mid range complexity and call density.



Cisco-router(config-voicecard)# codec complexity high

C5510 router(config)# voice-card 1 router(config-voicecard)# codec complexity ? flex

Set codec complexity Flex.

Flex complexity, higher call density.

high

Set codec complexity high.

High complexity, lower call density.

medium

Set codec complexity medium.

secure

Set codec complexity secure.

Mid range complexity and call density.

Cisco-router(config-voicecard)# codec complexity flex

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-11

Verifying Codec Complexity HQ-1# show voice dsp DSP DSP DSPWARE CURR BOOT PAK TX/RX TYPE NUM CH CODEC VERSION STATE STATE RST AI VOICEPORT TS ABORT PACK COUNT ==== === == ======== ======= ===== ======= === == ========= == ===== ============ ----------------------------FLEX VOICE CARD 0 -----------------------------*DSP VOICE CHANNELS* CURR STATE : (busy)inuse (b-out)busy out (bpend)busyout pending LEGEND : (bad)bad (shut)shutdown (dpend)download pending DSP DSP DSPWARE CURR BOOT PAK TX/RX TYPE NUM CH CODEC VERSION STATE STATE RST AI VOICEPORT TS ABRT PACK COUNT ===== === == ========= ======= ===== ======= === == ========= == ==== ============ *DSP SIGNALING CHANNELS* DSP DSP DSPWARE CURR BOOT PAK TX/RX TYPE NUM CH CODEC VERSION STATE STATE RST AI VOICEPORT TS ABRT PACK COUNT ===== === == ========= ======= ===== ======= === == ========= == ==== ============ C5510 002 01 {flex} 8.2.0 alloc idle 0 0 0/2/0 02 0 0/0 C5510 002 02 {flex} 8.2.0 alloc idle 0 0 0/2/1 02 0 0/0 ------------------------END OF FLEX VOICE CARD 0 ----------------------------

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-12

DSP Requirements for Media Resources  Number of DSPs depends on DSP type, required media resources, and codecs: – C5510 (used on PVDM2) has higher performance than C549 (used on PVDM)  Single DSP can only be used as a single media resource: – Either voice termination, conferencing, transcoding or MTP  DSP calculator helps calculation of required DSPs: – http://www.cisco.com/cgi-bin/Support/DSP/dsp-calc.pl – Support voice termination, conferencing, transcoding, and MTP

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-13

DSPs per PVDM2

© 2008 Cisco Systems, Inc. All rights reserved.

PVDM2

Number of C5510 DSPs

PVDM2-8

1/2

PVDM2-16

1

PVDM2-32

2

PVDM2-48

3

PVDM2-64

4

CVOICE v6.0—1-14

Conferencing DSP Resources

C549 (PVDM; for example, NM-HDV)

C5510 (PVDM2; for example, ISR, NM-HDV2)

Maximum Participants per Conference

6

8

G.711 Conferences per DSP

1

8

Mixed-Mode Conferences per DSP

1

2

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-15

Transcoding DSP Resources

C549 (PVDM; for example, NM-HDV)

C5510 (PVDM2; for example, ISR, NM-HDV2)

G.711 (a-law, mu-law) Sessions per DSP

4

16

G.729A, G.729AB, GSM FR Sessions per DSP

4

8

G.729, G.729B, GSM EFR Sessions per DSP

4

6

From Low Complexity To:

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-16

DSP Calculator

1 Select the router model.

2 Select the Cisco IOS release. DSP Calculator URL: http://www.cisco.com/cgi-bin/Support/DSP/dsp-calc.pl © 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-17

DSP Calculator (Cont.)

3 Select router VICs. 4 Specify the number of calls.

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-18

DSP Calculator (Cont.)

5

Specify the number of transcoding sessions.

6 Specify the number of conferences.

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-19

DSP Calculator Results

7 Calculate required DSPs or PVDMs.

© 2008 Cisco Systems, Inc. All rights reserved.

Sample Cisco IOS configuration.

CVOICE v6.0—1-20

Configuring Conferencing and Transcoding on Voice Gateway Routers 1. Determine DSP resource requirements 2. Enable SCCP on the Cisco Unified Communications Manager interface or Cisco Unified Communications Manager Express 3. Configure enhanced conferencing and transcoding

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-21

DSP Farm Configuration Example Chicago

San Jose Cisco Unified Communications Manager 10.1.1.201

IP WAN

Router1

Phone1-1 1001

Phone1-2 1002

sccp ccm 10.1.1.201 sccp local FastEthernet 0/0 sccp voice-card 0 dsp services dspfarm © 2008 Cisco Systems, Inc. All rights reserved.

Router2

PSTN

Phone2-1 2001

Phone2-2 2002

sccp ccm 10.1.1.201 sccp local FastEthernet 0/0 sccp voice-card 0 dsp services dspfarm CVOICE v6.0—1-22

DSP Profile Configuration Example Chicago

San Jose Cisco Unified Communications Manager 10.1.1.201

IP WAN

Router1

Phone1-1 1001

Phone1-2 1002

dspfarm profile 1 transcode codec g711ulaw codec g711alaw codec g729ar8 codec g729abr8 codec g729r8 maximum sessions 6 associate application SCCP no shutdown © 2008 Cisco Systems, Inc. All rights reserved.

Router2

PSTN

Phone2-1 2001

Phone2-2 2002

dspfarm profile 1 conference codec g711ulaw codec g711alaw codec g729ar8 codec g729abr8 codec g729r8 codec g729br8 maximum sessions 2 associate application SCCP no shutdown CVOICE v6.0—1-23

DSP Farm Configuration Commands for Enhanced Media Resource router(config)#

sccp ccm {ip-address | dns} identifier identifier-number [port port-number] [version version-number]

 Adds a Cisco Unified Communications Manager server to the list of available servers to which the Cisco voice gateway can register. router(config)#

sccp local

 Selects the local interface that SCCP applications use to register with Cisco Unified Communications Manager. router(config)#

sccp

 Enables SCCP and brings it up administratively. © 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-24

DSP Farm Configuration Commands for Enhanced Media Resource (Cont.) router(config)#

voice-card slot

 Enters the voice card configuration mode. router(config-voicecard)#

dsp services dspfarm

 Enables DSP farm services. router(config)#

dspfarm profile profile-identifier {conference | mtp | transcode}

 Creates a DSP farm profile for conferencing, MTP, or transcoding. © 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-25

DSP Farm Configuration Commands for Enhanced Media Resource (Cont.) router(config-dspfarm-profile)#

codec codec-type

 Specifies the allowed codecs. router(config-dspfarm-profile)#

maximum sessions number

 Defines the maximum number of sessions. router(config-dspfarm-profile)#

associate application SCCP

 Enables SCCP for the profile. © 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-26

Verifying Media Resources Router# show dspfarm profile 1 Dspfarm Profile Configuration Profile ID = 1, Service = CONFERENCING, Resource ID = 1 Profile Description : Profile Admin State : UP Profile Operation State : ACTIVE Application : SCCP Status : ASSOCIATED DSP farm profile active Resource Provider : FLEX_DSPRM Status : UP and associated with Number of Resource Configured : 2 SCCP Number of Resource Available : 2 Codec Configuration Codec : g711ulaw, Maximum Packetization Period : 30 , Transcoder: Not Required Codec : g711alaw, Maximum Packetization Period : 30 , Transcoder: Not Required Codec : g729ar8, Maximum Packetization Period : 60 , Transcoder: Not Required Codec : g729abr8, Maximum Packetization Period : 60 , Transcoder: Not Required Codec : g729r8, Maximum Packetization Period : 60 , Transcoder: Not Required Codec : g729br8, Maximum Packetization Period : 60 , Transcoder: Not Required

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-27

Verifying Media Resources (Cont.)

Router# show dspfarm dsp all SLOT DSP VERSION STATUS CHNL USE

TYPE

RSC_ID BRIDGE_ID PKTS_TXED PKTS_RXED

0 0

conf conf

1 1

5 5

1.0.6 1.0.6

UP UP

N/A N/A

FREE FREE

Total number of DSPFARM DSP channel(s) 2

© 2008 Cisco Systems, Inc. All rights reserved.

-

-

-

Two conference bridges configured

CVOICE v6.0—1-28

Summary  Codecs are used to compress and decompress various types of data that would otherwise use up large amounts of bandwidth.  Voice sample size is a variable that can affect the total bandwidth used.  Several factors must be included in calculating the overhead of a VoIP call.  Codec choice, data-link overhead, sample size, and RTP have positive and negative impacts on total bandwidth.  Codec complexity affects the call density.

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-29

Summary (Cont.)  DSPs enable Cisco platforms to efficiently process digital voice traffic.  The number of DSPs required is a key factor when deploying media resources using DSPs.  The configuration of transcoding and conferencing on a voice gateway involves several components.  DSP farm services are enabled on the voice card, and DSP profiles create the actual media resource.  You may verify DSP media resources using show dspfarm commands.

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-30

© 2008 Cisco Systems, Inc. All rights reserved.

CVOICE v6.0—1-31