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Lync Bandwidth Requirements

The bandwidth requirements for Lync are difficult to determine for a given customer installation especially since the nature of Lync is to change how people communicate. The starting point for understanding the network bandwidth requirements are documented on Technet and Microsoft have released a bandwidth calculator.

The bandwidth usage is determined by a number of factors, the Codec used (along with overhead), the Stream activity level and for video, the resolution/quality and frame rate.

Audio Codec Bandwidth

Audio codec

Scenarios

Audio payload bitrate

Add IP header only

Also add UDP, RTP and SRTP

Also add FEC

RTAudio Wideband

Peer-to-peer

29.0

45.0

57.0

86.0

RTAudio Narrowband

Peer-to-peer, PSTN

11.8

27.8

39.8

51.6

G.722

Conferencing

64.0

80.0

95.6

159.6

G.711

PSTN

64.0

80.0

92.0

156.0

Siren

Conferencing

16.0

32.0

47.6

63.6

The bandwidth rates are in Kbps (as are all bandwidth rates in this post) and assume 100% stream activity, which is not the normal case. (Note: The online Technet document shows KBPS (i.e. Kilo Bytes per second for the base Audio payload bitrate, it should be Kbps – reference Wikipedia)

Video Resolution Bandwidth

Video codec

Resolution

Maximum video payload bitrate

Minimum video payload bitrate

RTVideo

Main Video CIF

250

50

RTVideo

Main Video VGA

600

350

RTVideo

Main Video HD

1500

800

RTVideo

Panoramic Video

350

50

The maximum bitrate values shown (Kbps) are applicable for maximum frame rate and maximum quality. The minimum bitrate is for 1fps. HD Video is only available for peer-to-peer sessions. By default, only SD video is allowed, to allow HD video at Global or Site level use Set-CsMediaConfiguration –Identity:Global -MaxVideoRateAllowed HD720p15m

Bandwidth usage by participant

The raw bandwidth specified above is used only when the situation requires it, in other words, depending on what individual users are doing with the session determines their bandwidth requirements.

Peer-to-Peer

  • Endpoints send audio streams only when the users speak.
  • Both participants receive audio streams.
  • If video is used, both endpoints send and receive video streams during the entire call.

Conference

  • Endpoints send audio streams only when the users speak.
  • All participants receive audio streams.
  • If video is used, only two endpoints send a video stream at a time (the active speaker and the previous active speaker).
  • If video is used, all participants receive video streams.

Stream Activity Levels

Scenario

Media

Estimated stream activity (%)

Peer-to-peer sessions

Audio

61

Peer-to-peer sessions

Main video CIF

84

Peer-to-peer sessions

Main video VGA

83

Peer-to-peer sessions

Main video HD

80

Peer-to-peer sessions

Panoramic video

74

Conferencing

Audio

43

Conferencing

Main video CIF

84

Conferencing

Main video VGA

83

Conferencing

Main video HD

80

Conferencing

Panoramic video

74

PSTN

Audio

65

This is based on customer data gathered by Microsoft.

Added to the media bandwidth requirements is the requirement for control traffic in the form of Real Time Control Protocol (RTCP)

RTCP Bandwidth

Media

RTCP maximum bandwidth

Audio

5

Video

10

Overall Bandwidth by session type

Combining all this information together, Microsoft have come up with a table of maximum bandwidth utilisation (with and without FEC) and also typical bandwidth utilisation.

Audio/Video Capacity Planning for Peer-to-Peer Sessions

Media

Codec

Typical stream bandwidth

Maximum stream bandwidth without FEC

with FEC

Audio

RTAudio Wideband

39.8

62

91

Audio

RTAudio Narrowband

29.3

44.8

56.6

Main video CIF

RTVideo

220

260

Not applicable

Main video VGA

RTVideo

508

610

Not applicable

Main video HD

RTVideo

1210

1510

Not applicable

Panoramic video

RTVideo

269

360

Not applicable

Audio/Video Capacity Planning for Conferences

Media

Typical codec

Typical stream bandwidth

Maximum stream bandwidth without FEC

with FEC

Audio

G.722

46.1

100.6

164.6

Audio

Siren

25.5

52.6

68.6

Main video CIF

RTVideo

220

260

Not applicable

Main video VGA

RTVideo

508

610

Not applicable

Panoramic video

RTVideo

269

360

Not applicable

Audio Capacity Planning for PSTN

Media

Typical codec

Typical stream bandwidth

Maximum stream bandwidth without FEC

with FEC

Audio

G.711

64.8

97

161

Audio

RTAudio Narrowband

30.9

44.8

56.6

1 comment:

  1. Do you think Microsoft will ever utilize Skype's SILK codec in Lync, now that they MS has purchased Skype?

    ReplyDelete