2. UC403: Lync & Network Interaction
Lars H. Sørensen
Solution Architect, Microsoft Unified Communications
Atea Denmark

3. Agenda Lync & Network Interaction Call Setup Bandwidth Usage
Enemies on the Network
What to do ?

4. Lars H. Sørensen Aarhus, Denmark Solution Architect 19+ years in IT
10+ years with Microsoft UC

5. Call Setup

6. Protocols Session Initiation Protocol (SIP)
Session Description Protocol (SDP)
Interactive Connectivity Establishment (ICE)
Session Traversal Utilities for NAT (STUN)
Traversal Using Relay NAT (TURN)

8. Call Setup IP Candidate Discovery Invite & IP Candidate Exchange
Connectivity Checks
Candidate Promotion

9. IP Candidate Discoveryb
Allocate UDP b c c d
Allocate TCP e d e

10. Invite & IP Candidate Exchangew y z a b c d e
SIP INVITE
a,b,c,d,e a b c d e w y z
183 Session Progress
w,y,z
200 OK
w,y,z a c a b w b e c d y d e z

11. Connectivity Checks Determine all possible UDP and TCP port pairings
STUN packets sent between port pairs in order
STUN packet response indicates connectivity
Stop checks when candidate pair has bi-directional connectivity

12. Candidate Promotion
Select highest order candidate with validated connectivity
Send SIP invite, indicating only candidate is in SDP
200 OK also contains only one candidate in SDP
Note there will be two candidates, one RTP and one RTCP
Media is redirected to flow on optimal, validated path

13. Connectivity Checks & Candidate Promotionw y z a b c d e
SIP INVITE b û û a b c d e w y z
200 OK y û û û û û û û ü ü û û û û û û û û û ü ü û c û a û w b e ü ü û y d ü ü z

14. NAT (Home) Network Address Translation General NAT/Firewall behavior
Translates one or more internal addresses to one external address
General NAT/Firewall behavior
Allow connections from the private network
Blocks connection from the Internet
Security/usability tradeoff
Blocks attackers from harming your system
PROBLEM: Also blocks incoming signaling and media

15. NAT (Corporate) Though more scrutinized, goals are similar
Sharing of IP addresses
Controlling data traffic from the internet
Two firewalls isolate via perimeter network
PROBLEM: Also blocks incoming and outgoing signaling and media

16. Why is NAT Traversal a problem ?
SIP signaling over TCP uses Access Edge
UDP media flows over separate channel
Pre-ICE endpoints uses local IPs & ports
No media can be sent between (a) and (w)
INVITE
m/c = a
200OK
m/c = w a w

17. Types of NAT Full Cone NAT IP Address Restricted NAT
Port Restricted NAT
Symmetric NAT

18. Full Cone, IP Address Restricted & Port Restricted
STUN will be supported
Type
Inside Host (H1)
NAT
Outside Host
Full Cone
:1111
:2222
*:*
IP Address Restricted
:1111
:2222 :*
IP Address Restricted
:1111
:2222 :*
Port Restricted
:1111
:2222
:3333
Port Restricted
:1111
:2222
:4444

19. Symmetri NAT Does not work with STUN, must use TURN Type
Inside Host (H1)
NAT
Outside Host
Symmetri
:1111
:1234
:3333
Symmetri
:1111
:2345
:4444

20. STUN, TURN, ICE Add a Media Relay (aka A/V Edge Server)
STUN reflects NAT addresses (b) and (e)
TURN relays media packets (c) (d) (x) (y)
ICE exchanges candidates (cand) and determines optimal media path
INVITE
m/c = a
200OK
m/c = w
cand=a,b,c,d,e
cand=w,x,y a b c w e d x y

21. Internal to Internal Call
UDP
3478
TCP
443 w1
UDP/TCP
50000 .
59999 w1 w1 w2 w2 w2

22. Internal to External Callh1
UDP
3478
TCP
443 h1 h1 w1
UDP/TCP
50000 .
59999 h1 h1 w1 w1

23. External to External Callh1
UDP
3478
TCP
443 h1 h1
UDP/TCP
50000 .
59999 h2 h2 h2 h2 h1 h2 h1

25. Bandwidth Usage

26. P2P Call Media Codec Typical stream bandwidth (Kbps)
Audio
62 Kbps
Video
4010 Kbps
Media
Codec
Typical stream bandwidth (Kbps)
Maximum stream bandwidth without FEC
Maximum stream bandwidth with FEC
Audio
RTAudio Wideband
39.8 62 91
RTAudio Narrowband
29.3
44.8
56.6
Main video when calling Lync 2013 endpoints
H.264
460
4010 (for maximum resolution of 1920x1080)
Not applicable

27. Conference Call Audio Video (MultiView) 1xTx 1x101Kbps = 101Kbps
2xRx 2x101Kbps = 202Kbps
Video (MultiView)
Default (212x160)
3xTx 1x260Kbps = 780Kbps
3xRx 2x260Kbps = 1560Kbps
PopOut (424x320)
2xTx 1x460Kbps and 3xTx 1x260Kbps = 1700Kbps
1xRx 2x460Kpbs and 2xRx 2x260Kbps = 1960Kbps

28. Enemies on the Network

29. Latency Latency vs. Round Trip Time (RTT)
Provision your network to ensure a maximum end-to-end delay (latency) of 150 milliseconds (ms) under peak load.
When latency is high, users will likely hear the words, but there will be delays in sentences and words.
Lync Monitoring Thresholds
< 200 ms is good
> 200 ms is poor
> 500 ms is bad

30. Jitter
Variability of packet delay. Results in a distorted or choppy experience.
Jitter can increase total latency
Lync Monitoring Thresholds
< 20 ms is good
> 30 ms is not good (but can be ‘ok’)
> 45 ms is considered very bad

31. Packet Loss
Represents the % of packets that did not make it to their destination.
Packet loss will cause the media to be distorted or missing.
Lync Monitoring Thresholds
< 3% is considered good
> 5% will impact audio
> 7% is not good
> 10% is very bad
Divide by two when media is video.

32. Wi-Fi Usual built for data and fixed location Off-Channel Scanning
Handover Performance
Rate Adaption and TX Retries
Lack of QoS
Devices / BYOD

33. What to do ?

34. Optimal Media Path
Direct before relay
UDP before TCP

35. Optimal Media Path Port range open Port range closed 443 TCP 3478 UDP
50,000
port range
50,000
port range
443 TCP
3478 UDP
443 TCP
3478 UDP
50,000
port range
50,000
port range

36. Quality of Service (QoS)
What is QoS?
Quality of Service (QoS) is a combination of networking technologies that enables organizations to optimize the end-user experience for real time audio and video communications
When is QoS needed?
QoS is commonly used when network bandwidth is limited
QoS is needed when there is a possibility of network congestion

37. Quality of Service (QoS)

38. Quality of Service (QoS)
Lync Server 2013 enables both defined port ranges and DSCP marking
WMM-capable wireless access points translate DSCP markings into the equivalent WMM tag value
Validating QoS on Lync Endpoints

39. Quality of Service (QoS)
Lync Monitoring Server and Reports is your best friend.

40. A word or two on Wi-Fi
Delivering Lync 2013 Real-Time Communications over Wi-Fi:

41. Resources Lync Deep Dive: Edge Media Connectivity with ICE
Network Bandwidth Requirements for Media Traffic
Lync 2010 and 2013 Bandwidth Calculator
Network Planning, Monitoring, and Troubleshooting with Lync Server
Delivering Lync 2013 Real-Time Communications over Wi-Fi

42. Match of technical Level
Evaluation Scale:
1 = Very bad
2 = Bad
3 = Relevant
4 = Good
5 = Very Good!
Questions:
Speaker Performance
Relevance according to your work
Match of technical level according to published level
Comments
Evaluation
Create a Text message on your phone and send it to 1919 with the content:
UC I liked it a lot
Session Code
Lars
Performance (1 to 5)
Relevance
(1 to 5)
Match of technical Level
(1 to 5)
Comments
(optional)

43. Thank you
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