Ståle HansenLync Server 2013

Network Quality considerations in LAN, WAN and Wi-Fi

ObjectiveBetter understanding of Lync 2013 and network impact

• What is “Good” Voice Quality?• VoIP Metrics• Codecs and Bandwith• LAN, WAN and Wi-Fi

Ståle HansenTechnical Evangelist @ AteaV-TSP @ Microsoft

Blog @ msunified.netCompany blog @ LyncAtea.noCo-Author Lync Master Class @ LyncLab.noContributor @ TheUCArchitects PodCast

#NICLync#NIC2013@StaleHansen

What is “Good” Voice Quality?• Users not noticing Voice Quality issues

• is what defines success here

VoIP MetricsWhat are we looking for?

Delay / Latency• Recommendation

• Keep combined total two way delay below 150 ms

Packet Loss• Requirement for traditional VoIP

• Limit to < 1% loss (end to end)

• Requirement for RTAudio• Limit to < 10% loss (end to end)

Jitter• Requirement for VoIP

• Limit jitter to < 30ms

DemoImpact on a Lync conversation

11 22 33 44 55

11 4422 5533

SRTP / RTCP

SIP

Perfect Network

22 33 44 5533 44

FForward orward EError rror CCorrectionorrection

FForward orward EError rror CCorrectionorrection

55 66

1122

33

44

22

33

4455

11 4422 55

11 22 44 55

11 22 33 44 55Poor

Network

SRTP / RTCP

SIP

Codecs and Bandwith

Bandwidth• Media Endpoints detect & manage distribution of available BW

• Prioritize Audio first

• Bandwidth requirements determined by• Codec choice• Network performance• Channel Activity

Bandwith (BW)Codecs and Bandwith requirements

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.

Bandwith – Video

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

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• 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

Bandwith – Application Sharing

Bandwith (BW)Planning recommendations

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.

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Video Bandwidth Recommendations

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DemoSet-CsConferencingPolicy

NetworkLAN, WAN and Wi-Fi

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

Seattle WAN Link Policy:Audio Session Limit = 60 Kbps

RT Audio WB (no FEC)

New York

SeattleInternetWAN Link Policy:

Audio Session Limit = 60 Kbps

RT Audio WB (No FEC)

SeattleInternetWAN Link Policy:

Audio Session Limit = 60 Kbps

RT Audio NB (+ FEC)

DemoBandwith Calculator Overview

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

Quality of Service (QoS)

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

Challenge: DSCP tagging is not done by Lync

It’s done on OS level

Endpoint diversity

LAN Wi-Fi

Bring Your Own Device

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

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)

The 802.11 family explained• 802.11a

• 5 GHz• 54 Mbps

• 802.11b• 2,4 GHz• 11 Mbps

• 802.11g • 2,4 GHz• 54 Mbps

• 802.11n• 2,4 GHz (70 Mbps)• 5 GHz (150 Mbit)• Multiple channels• Multiple antennas (MIMO)

Device Wi-Fi support• Nokia Lumia 820

• 802.11a/b/g/n• HTC 8S Atlantic Blue

• 802.11b/g/n• HTC One X Plus Black

• 802.11a/b/g/n• Samsung GT-I8750 Ativ S

• 802.11a/b/g/n• Samsung Galaxy S III

• 802.11a/b/g/n• Apple iPhone 5

• 802.11a/b/g/n• Apple iPad mini Wi-Fi

• 802.11a/b/g/n

• Samsung ATIV Smart PC Pro• 802.11n

• Samsung Galaxy Tab 2 10.1“• 802.11b/g/n

• HP Envy X2 11-g001• 802.11n

• Apple iPad 2 Wi-Fi• 802.11a/b/g/n

• Microsoft Surface RT• 802.11a/b/g/n

• Microsoft Surface RT• 802.11a/b/g/n

• Microsoft Surface PRO• 802.11a/b/g/n

Voice optimized Wi-Fi• Aruba

• Lync certified solution

• Meru• Lync certified solution (March)

• Cisco• Lots of experience of voice over Wi-Fi

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

Data Center L2/L3

Aruba• Fingerprinting to detect multimedia endpoints

• Tag Lync traffic

• Multichannel AP deployment• Fast AP handover• Will redirect clients to AP’s with less load

Meru• Uses single SSID accross the entire

deployment• Zero-Latency Roaming

• Uses three channels with three different speeds

• Easy deployment, just add AP’s

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

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

Questions?