This document discusses network quality considerations for Lync 2013 voice over IP (VoIP) in local area networks (LANs), wide area networks (WANs), and wireless networks (Wi-Fi). It defines good voice quality as when users do not notice issues. Key VoIP metrics that should be monitored include latency, packet loss, and jitter. Codec choices and available bandwidth impact quality. The document provides bandwidth recommendations and demonstrates tools for planning voice and video capacity. It also covers call admission control, quality of service tagging, wireless access point deployment best practices, and wireless network optimizations from vendors like Aruba, Meru, and Cisco to improve voice quality over Wi-Fi.

1. Ståle Hansen
Lync Server 2013
Network Quality considerations in LAN,
WAN and Wi-Fi

2. Objective
Better understanding of Lync 2013 and network impact
• What is “Good” Voice Quality?
• VoIP Metrics
• Codecs and Bandwith
• LAN, WAN and Wi-Fi

3. Ståle Hansen
Technical Evangelist @ Atea
V-TSP @ Microsoft
Blog @ msunified.net
Company blog @ LyncAtea.no
Co-Author Lync Master Class @ LyncLab.no
Contributor @ TheUCArchitects PodCast

4. #NICLync
#NIC2013
@StaleHansen

5. What is “Good” Voice Quality?
• Users not noticing Voice Quality issues
• is what defines success here

6. VoIP Metrics
What are we looking for?

7. Delay / Latency
• Recommendation
• Keep combined total two way delay below 150 ms

8. Packet Loss
• Requirement for traditional VoIP
• Limit to < 1% loss (end to end)
• Requirement for RTAudio
• Limit to < 10% loss (end to end)

9. Jitter
• Requirement for VoIP
• Limit jitter to < 30ms

10. Impact on a Lync conversation
Demo

11. SIP
SRTP / RTCP
11 22 33 44 55
Perfect
Network
11 22 33 44 55

12. SIP
SRTP / RTCP
11 22 44 55
55
44 11 22 44 55
44
33
33
22
22
11 22 33 44 55 11
Poor
FForward Error
orward Error
CCorrection
orrection Network
22 33 33 44 44 55 55 66

13. Codecs and Bandwith

14. Bandwidth
• Media Endpoints detect & manage distribution of available BW
• Prioritize Audio first
• Bandwidth requirements determined by
• Codec choice
• Network performance
• Channel Activity

15. Bandwith (BW)
Codecs and Bandwith requirements

16. For planning in a well
managed, right-sized network,
use Max BW w/o FEC.
If the network will be
constrained and you want to
preserve quality, use Max BW
with FEC.
When understanding how
much bandwidth at any given
time is being used, use the
Typical BW numbers. Not for
planning, as usage will be
greater at times.

17. Bandwith – Video

18. Typical Video Bandwidth Usage
• Preliminary data from Lync 2013 Preview deployments at Microsoft and
TAP customers
• Video usage doubled compared to Lync 2010
• P2P video calls:
• Average send/receive video bandwidth ~600kbps
• ~75% of users with default video resolution of 424x240
• ~25% increase video window to obtain 640x360 or HD video
• Conference video calls:
• Data sharing reduces screen real estate for video in most calls -> small video
resolution of 320x180
• Receive: average of 2.5 video streams using ~500kbps
• Send: average of 1.6 video streams using ~350kbps
18

19. Bandwith – Application Sharing
• Application sharing bandwidth consumption
dependent on session content and screen
resolution
• TCP based sessions with built-in congestion control
• Traffic is bursty in nature
• End user policy limits to cap spikes

20. Bandwith (BW)
Planning recommendations

21. Video Bandwidth Recommendations
• Control maximum bandwidth by using
• VideoBitRateKB
• TotalReceiveBitRateKB
• Recommended settings:
• Send and receive limits should be set to same value
• Default: Best quality. For networks which can handle average
video bitrates of 600kbps for P2P and 200kbps for conference calls
• 1000 kbps: Usually 848x480 in P2P and 240x240 resolution in
multi-view
• 350 kbps: Requires multi-view to be disabled. Allows 424x240
resolution.
21

22. Video Bandwidth Recommendations
22

24. Set-CsConferencingPolicy
Demo

25. Network
LAN, WAN and Wi-Fi

27. Call Admission Control (CAC)
• Policy Server role in Lync Server implements CAC
• Admins configure logical sites based on groupings of subnets
• WAN link bandwidth policies
• Applied dynamically when session crosses network link with policy
set
• Seamless support for roaming users on moving between different
sites
• PSTN reroute
• Allows Internet to be used for overflow of traffic
• Support alternate path & failover of video sessions

28. RT Audio WB (no FEC)
Seattle WAN Link Policy: New York
Audio Session Limit = 60 Kbps

29. RT Audio WB (No FEC)
Internet Seattle WAN Link Policy:
Audio Session Limit = 60 Kbps

30. RT Audio NB (+ FEC)
Internet
Seattle WAN Link Policy:
Audio Session Limit = 60 Kbps

31. Bandwith Calculator Overview
Demo

32. End to end networking
• LAN
• WAN
• Wi-Fi

33. Quality of Service (QoS)

34. Differentiated Services Code Point (DSCP)
…AKA DiffServ
•Recommended:
• When Right Provisioning not possible and on
Constrained WAN Links
• pair with WAN bandwidth policies
• Prioritization already deployed for other VoIP
solution

35. Challenge:
DSCP tagging is not done by Lync
It’s done on OS level

36. Endpoint diversity
LAN Wi-Fi
Bring Your Own Device

37. Wi-Fi problem areas
• Shared medium
• Limited band selection in 2.4 GHz band
• Was designed for none-real time data usage
• Deployed for access, not throughput

38. Microsoft recommendation
• Deploy concurrent dual-band AP
• Applicable for enterprise, home, and hotspot
• Move devices to 5 GHz (if possible) 21 channels
• Less interference
• Wider channel selection
• Consider quality and features of Wireless NICs
• Wi-Fi alliance certification
• Multiple antennae support (11n)

39. The 802.11 family explained
• 802.11a • 802.11g
• 5 GHz • 2,4 GHz
• 54 Mbps • 54 Mbps
• 802.11b • 802.11n
• 2,4 GHz • 2,4 GHz (70 Mbps)
• 11 Mbps • 5 GHz (150 Mbit)
• Multiple channels
• Multiple antennas
(MIMO)

40. Device Wi-Fi support
• Nokia Lumia 820 • Samsung ATIV Smart PC Pro
• 802.11a/b/g/n • 802.11n
• HTC 8S Atlantic Blue • Samsung Galaxy Tab 2 10.1“
• 802.11b/g/n • 802.11b/g/n
• HTC One X Plus Black • HP Envy X2 11-g001
• 802.11a/b/g/n • 802.11n
• Samsung GT-I8750 Ativ S • Apple iPad 2 Wi-Fi
• 802.11a/b/g/n • 802.11a/b/g/n
• Samsung Galaxy S III • Microsoft Surface RT
• 802.11a/b/g/n • 802.11a/b/g/n
• Apple iPhone 5 • Microsoft Surface RT
• 802.11a/b/g/n • 802.11a/b/g/n
• Apple iPad mini Wi-Fi • Microsoft Surface PRO
• 802.11a/b/g/n • 802.11a/b/g/n

41. Voice optimized Wi-Fi
• Aruba
• Lync certified solution
• Meru
• Lync certified solution (March)
• Cisco
• Lots of experience of voice over Wi-Fi

42. How to optimize for voice over Wi-Fi
• All vendors tag Wi-Fi Lync traffic with DSCP value
• Great for unmanaged devices
• High-density AP deployments
• Closer to users
• Just add more accesspoints
• Fast inter-AP handover support
• All venderos stress end to end optimization
• Endpoint -> Wi-Fi -> LAN -> WAN -> LAN -> Wi-Fi -> Endpoint

43. Data Center L2/L3

44. Aruba
• Fingerprinting to detect multimedia endpoints
• Tag Lync traffic
• Multichannel AP deployment
• Fast AP handover
• Will redirect clients to AP’s with less load

45. Meru
• Uses single SSID accross the entire
deployment
• Zero-Latency Roaming
• Uses three channels with three different
speeds
• Easy deployment, just add AP’s

46. Cisco
• Just released AVC that tag Lync traffic at AP
• Deep packet inspection
• AVC profiler
• En for voice og video
• MS Lync
• Band select, forcing acces points to 5 GHz
• If one acces point goes down
• Coverage hole detection, increase send strength
• Uses its CleanAir technology to detect interference
• Spectrum analyzer
• All new access points have this today
• Change channel when noise

47. Key Takeaways
• “Good” Voice Quality - is what is expected
• VoIP Metrics – Tells us about the health of the
network
• Codecs and Bandwith – Helps us design for QoE
• LAN, WAN and Wi-Fi – Wi-Fi is the new norm

48. Questions?