The document discusses how to conduct a proof of concept (POC) using HP Network Virtualization tools. It describes scoping the POC by discussing the application, objectives, prerequisites and selecting network test scenarios. The goals are to demonstrate the value of the tools, ensure a successful POC by keeping the scope well-defined, and progress the sales process by showing results meet success criteria. Network impairments like latency, jitter and bandwidth constraints can impact the user experience and should be considered in test scenarios.

1. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
HP Network Virtualization
(NV) Enablement
– How to POC
Matthew Brady – EMEA NV Pre-Sales
15th May 2014

2. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.2
POC Overview
Scoping (Discovery)
Objectives
Pre-Requisites
How to Select Network Scenarios
What to Cover
How to Test
How to Report
Follow Up
Agenda
Content Intended as Aide Memoire/Checklist
- Won’t Cover All Points
- Questions/Feedback Throughout!

3. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
POC Overview

4. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.4
Proof of Concept
“A proof of concept (POC) … is a realization of a certain method or idea to
demonstrate its feasibility, or a demonstration in principle, whose purpose
is to verify that some concept or theory has the potential of being used. A
proof of concept is usually small and may or may not be complete”
- Wikipedia
What is a POC?
• Not a Trial (Self-Guided)
• Not a Pilot (Actual Project Deliverables)
• Limited in Scope and Length
• Low number of vusers
• 2-3 days total time
• Single Application
• Limited Journeys
• Usually Assisted
Give-Get?
• Sponsor Required
• Conditional Commitment/Access to Power
• Final Results Presented to Power

5. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
POC Scoping

6. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.6
Overall
• What Is The Name And Description Of The Application To Be Covered By The POC?
• Who Will Be Involved?
• Where Will It Be Run, Using What Resources?
Architecture/Technology
• What Is The Outline Architecture Of The Application (Overview Only Is Required)?
• Which Client Platforms Will Be Used (Windows/Android/Ios)? Which Client Types
Should Be Included In The POC Test Activities?
• How Will It Be Delivered To Users (Web Browser, Client Application, Mobile App Etc.)
And Using Which Technologies (HTML5/JS/.Net/Java Etc.)?
Scoping Questions

7. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.7
Geography/Connectivity
• Where Will It Be Hosted When In Production?
• Who Will Be The End-users? Where Will They Be Located? How Will They Be
Connected?
• Is The Client Communication Encrypted (Https)?
• If Mobile Users, Which Operators And Connection Types (2.5g, 3g, 3.5g, 4g)?
• If Web Users, Which Connection Types (Dialup, Dsl, Cable, Satellite, Other)?
Types Of Testing/Tools
• Single-user Functional And/Or Multi-user Non-functional
• Manual, UFT, LR/PC, Sprinter And/Or SV
• Desktop, Web And/Or On-device
Scoping Questions

8. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.8
Scripting/Automation
• Do LR Scripts Exist For The Application Already? If So, How Many Are There? What
Protocols Do They Use? Which Ones Will Be Selected For The POC?
• If Lr Scripts Do Not Exist, When Will They Be Available? Which Protocols Will They
Use?
• Which Lr Version Is Currently Installed? Will The POC Use This Environment Or Will A
New Environment Be Setup For The POC? What OS Is Used For LR Controllers/Load
Generators?
Objectives
• What Is The Test Objective?
• 5000 Concurrent Users, 100k Transaction Per Hour, Functional Tests?
• How Will Test Success Be Determined (E.g. Response Times, Server CPU Etc.)?
• What Slas Or Other Requirements Exist?
Scoping Questions

9. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
POC Objectives

10. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.10
NV With LR/PC
• Record/Sample Remote Network Conditions
• Configure And Apply Network Conditions In Tests, Including Additional Reporting
Capabilities
• Analyse The Impact Of Remote Users On System Load
• Analyse And Optimize The Application Flows For Performance
Success Criteria
Client Objectives – Multi User Testing
Criterion Status after POC
Install, license and configure HP NV software components Complete
Demonstrate HP Network Catcher to profile/sample mobile network
conditions
Complete
Execute automated tests using HP NV for HP to apply network
conditions
Complete
Demonstrate additional HP NV reporting and metrics Complete
Demonstrate using HP NV Analytics to optimize and improve
performance of application flows
Complete
Provide comparison report and analyse comparative throughput of
network virtualization in tests
Complete

11. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.11
NV For Desktop/Mobile
• Install, License And Deploy Of HP NV For Mobile
• Record/Sample Mobile Network Conditions For UK Consumers
• Apply Network Conditions, Time Transactions And Capture Traffic Flowing From On-device
Tests
• Analyse And Optimize The Application Flows For Performance Including HTTPS Decoding
• Demonstrate Using API/Command Line To Control Network Conditions For Automation
Success Criteria
Client Objectives – Single User Testing
Criterion Status after POC
Install, license and configure HP NV software components Complete
Demonstrate HP Network Catcher to profile/sample mobile network
conditions
Complete
Execute manual and automated on-device tests using HP NV for
Mobile to apply network conditions
Complete
Demonstrate additional HP NV reporting and metrics Complete
Demonstrate using HP NV Analytics to optimize and improve
performance of application flows
Complete
Provide comparison report, and analyse comparative throughput of
network virtualization in tests
Complete

12. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.12
1. Ensure Successful POC
• Keep it Simple, Well-defined Scope
• Ensure S/W Pre-installed
• Check & Verify Objectives, Prerequisites
• Limit Time/Effort but Provide Maximum Results
2. Demonstrate Maximum Value/Impact
• Work Towards the Final Report – Not Client-Defined Schedule
• Carefully Select Network Test Scenarios – Include Worst Cases
• Opt For Poorer Network Conditions
3. Progress Sales Process
• Agree Success Criteria Before POC
• Demonstrate Compliance to Success Criteria
• Provide Detailed Report With Executive Summary
• Present Results to Executive Team
HP Objectives?

13. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
POC Prerequisites

14. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.14
Environment
• Identify Testing Servers
• Controller(s), Load-Gens
• Scripting Workstation
• Testing Workstation
• Check Admin Rights
• Check Server Specification/OS Version etc.
Resources
• When can the Application be tested? Will it remain unchanged through the POC?
• Required Additional Software (Java, Silverlight)
• Internet Connectivity (for NC Global Library etc.)
• Software Download(s)
• Demo Licenses & Extensions
Prerequisites

15. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.15
LoadGen
All Protocols Except Citrix
NV for LR/PC
Networ
k NV-M
LoadGen
NV-M
LoadGen
NV-M
NV-M
(Controller
Component
)
NV-M
(PC Server
Component
)
* 1 day minimum checkout period
LM??
License
NV
Analytics
NV
Predictor
(+MS
Office)
Controller PC Server
Internet
OR
OR
OR
EITHER
NC Global DB

16. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.16
Desktop & Web Apps, Manual or Automated Testing (UFT, Sprinter etc.)
NV for Mobile (Desktop Mode)
Networ
k
App Under
TestNV-M
License
s
LM?
NV
Analytics
EITHER
OR
NV
TM

17. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.17
On-Device Native, Hybrid & Web Apps
NV for Mobile (Mobile Mode)
Networ
k
Proxy
New Wifi
Hotspot
On-Device Web
Interface
Desktop Web
Console
NV-M
* 1 day minimum checkout period
NV
Analytics
SSL Key

18. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
How to Select Network
Test Scenarios

19. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
Let’s Begin with a Bit of Theory

20. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
The Network Impact
20
Tokyo
LondonNew York
New York
Data Center
WAN
Consider 3 Users - 1 in NY, 1 in London And 1 in Tokyo
• All Users Access the Same Application in the NY Data Center
• Will They All Experience the Application in the Same Way?
• If Not, Why Not?

21. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.21
Network Impairments
21
Conditions which inhibit the flow of data across a network
• Key Impairments are:
• Network Delay (Latency)
• Jitter (Delay variation, inter-packet gap variation)
• Packet Loss (inverse of delivery rate)
• Bandwidth Constraints
• Bandwidth Utilization

22. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.22
Mobile Network Impairments
22
Mobile Networks Experience Extreme Conditions of the Same Net
Impairments
• More Network Delay (Last Mile + Backhaul, RRC latency)
• More Jitter (Delay variation, inter-packet gap variation)
• More Packet Loss (inverse of delivery rate)
• More Bandwidth Constraints
• More Bandwidth Utilization

23. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.23
Why is There Delay on a Terrestrial Network?
23
A Bt (msec) = d / (2/3)c
Signal
d
Packet PacketPacket Packet Packet
BUSY
Lost Packet
Network Delay
• Propagation Delay
• Processing / Insertion / Serialization Delay
• Queueing Delay

24. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.24
New York
London
Frankfurt
Tokyo
Sydney
Signal Speed - Geography
24
• Speed of Light = 299,792.458 km/s
New
York
London Frankfurt Tokyo Sydney
New York 5,585km 6,219km 10,871km 15,998km
London 639km 9,585km 16,991km
Frankfurt 9,357km 16,480km
Tokyo 7,793km
New
York
London Frankfurt Tokyo Sydney
New York 28ms 31ms 54ms 80ms
London 3ms 48ms 85ms
Frankfurt 47ms 82ms
Tokyo 39ms
T = D / (2/3)c
Distance
Theoretical
Minimum
Signal Time
(One Way)

25. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.25
25
Combination of:
• Server Connect Latency (First Mile)
• Back-Haul/Propagation Latency
• Client Connect Latency (Last Mile)
Total Latency
First Mile
Last Mile
Propagation Latency

26. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.26
Internet Consumer (Last Mile) Latency
26
Connection
Type
RTT
Fiber 17ms
Cable 28ms
DSL 44ms
http://www.fcc.gov/measuring-broadband-america
Broadband Latency (FCC)
• “Fiber-to-the-home services provided 17 ms round-trip latency on average, while
cable-based services averaged 28 ms, and DSL-based services averaged 44 ms.”

27. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.27
Mobile Latency
Mobile
Cell Tower
Mobile
Last Mile
50ms to 800ms
Up to 50% Packet Loss
BW 56Kbps to 20Mbps
Origin
Server
Mobile
Device

28. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.28
Mobile Latency – 1st Data point
28
http://stakeholders.ofcom.org.uk/binaries/research/telecoms-research/bbspeeds2010/Mobile_BB_performance.pdf
Ofcom study, UK Mobile Networks, May 2012
Static Tests:
• “Latency… was an average of 117 milliseconds. Nearly two thirds of tests took more than 100
milliseconds”
User Panel:
• “Average latency was 192 milliseconds and around a third of tests delivered latency of higher than 200
milliseconds”

29. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.29
Mobile Latency – 2nd Data point
29
Cisco Cloud Index, 2010-2015
“Global average fixed latency is 125ms and average mobile latency is 290ms… Global
mobile consumer average latency is 307.3ms”

30. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.30
Latency – Summary of Averages
30
0
50
100
150
200
250
300
350
Fiber Cable DSL Mobile
(Ofcom Tests)
Mobile
(Ofcom
Panel)
Mobile
(Cisco)
Mobile
Consumer
(Cisco)
Latency by Connec on Type

31. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.31
Packet Loss
31
Random Early Detection
Average queue monitored size & packets
dropped based on statistical probabilities. If
buffer is almost empty, all incoming packets are
accepted. As queue grows, probability of
dropping incoming packet grows. When buffer is
full, probability reaches 1 and all incoming
packets are dropped.
Packets get dropped on an end to end link due to the following:
• Network congestion causes queues to saturate
• Network congestion triggers RED
• Interference on wireless networks
• Hardware errors
• Firewall Policies
Packet loss is the inverse of delivery rate
100% - packet loss rate = delivery rate

32. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.32
Packet Loss
32
http://pam2012.ftw.at/papers/PAM2012paper6.pdf
Packet Loss, Akamai/MIT Research
• Tested 149 Million connections in 51 countries
• Compared PL for mobile networks from non-mobile networks
• Most connections have no packet loss (Median PL is 0%).
• 75th percentile usually zero too
• Average connection packet loss: 2.5%
• Fixed network average is 2.2%
• Implies connections are usually fine, but sometimes terrible
• The average PL for the non-zero half is 5%
• Suggests “small” connections have higher Packet Loss
• HTTP Connections are often small

33. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.33
Jitter
33
Jitter
No Jitter
Jitter-Sensitive Applications:
• Video
• VoIP
Jitter = Variability over time of latency across a network
• PDV – Packet Delay Variation
Constant Latency = Zero Jitter

34. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.34
Mobile Bandwidth in Theory
34
Protocol Max Downlink Max Uplink
GPRS 56-115 Kbps
CDMA200 (1X) 153.6 Kbps
Edge 236.8 Kbps
3G Bar 2 Mbps stationary client
384 Kbps moving client
EV-DO 2.5-4.9 Mbps 0.15-1.8 Mbps
EDGE Evolution 1.6 Mbps 0.5 Mbps
HSDPA 2 Mbps 200 Kbps
HSPA+ 14.4 Mbps
4G Bar 1 Gbps stationary client
100 Mbps moving client
HSPA+ Release 11 21-672 Mbps 5.8-168 Mbps
LTE 100-300 Mbps 50-75 Mbps
WiMax 37-365 Mbps 17-376 Mbps

35. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.35
Mobile Bandwidth
35
You only get those speeds it if you’re this
guy…

36. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.36
Mobile Bandwidth
36
Source (PCWorld): http://bit.ly/JX7MQw
PCWorld/Novarum
3G
• Download: 0.59 – 3.84 Mbps
• Upload: 0.56 – 1.44 Mbps
4G
• Download: 2.81 – 9.12 Mbps
• Upload: 0.97 – 5.86 Mbps
Date: Apr, 2013

37. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.37
Download BW Impact on Load Time
DSL
Cable FIBER
Poor Cell Conn
Avg Cell Conn
Load Time (ms)
Download BW (Kbps)

38. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.38
Upload BW Impact on Load Time
DSL
Cable FIBER
Poor Cell Conn Avg Cell Conn
Load Time (ms)
Upload BW (Kbps)

39. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.39
Latency Impact
DSL
Cable
FIBER
Poor Cell Conn
Avg Cell Conn
Load Time (ms)
Latency (ms)

40. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.40
Network Profiles – Conclusions for Performance
Upload BW doesn’t matter much until <200 kbps
Download BW Matters at Low Values <1Mbps
• Unless Transfer Volume (Data) is Large
Latency matters the most
Packet Loss is Important but causes variation in results
• Only use in Worst Network Conditions

41. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
How to Select Network Test
Scenarios

42. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.42
1. Determine the Full Range of Client Connection Types, for example:
• Remote Office Tokyo, London
• Consumer Web UK, Germany
• Consumer Mobile 2.5G India, UK, Germany
• Consumer Mobile 3G UK, Germany, Japan
• Consumer Mobile 4G UK, Japan
2. Select Test Range of Network Conditions (Not All):
• Remote Office London
• Remote Office Tokyo
• Consumer Web Europe Typical
• Consumer Mobile 4G UK Best
• Consumer Mobile 3G Europe Typical
• Consumer Mobile 2.5G India Worst
Selecting the Network Values for a POC

43. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.43
1. Work Out One-way Propagation Delay Server To Clients
• Calculate KM Distance/200,000
2. Attempt To Validate Using Ping Tests
• Or Use Other Tools – Try To Exclude The Last Mile
3. Demonstrate Mechanisms To Capture Network Conditions …
• NC Server/Agents
• NC App
• NC Global Library
• Other Tools/Data
But Do Not Use The Results In The POC
Selecting the Network Values for a POC

44. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.44
5. Select Test Range of Network Conditions (Not All):
• Remote Office London
• Remote Office Tokyo
• Consumer Web Europe Typical
• Consumer Mobile 4G UK Best
• Consumer Mobile 3G Europe Typical
• Consumer Mobile 2.5G India Worst
6. … Which Are:
• Representative
• Predictable
• In Sequence
Selecting the Network Values for a POC (cont.)
Use:
• Manual, Static Definitions
• Stepped Latency & Bandwidth (Equally Spread?)
• Static (Zero?) Packet Loss (Except Final Case)

45. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.45
Example Network Test Profiles
• Baseline 0ms 100Mbps/100Mbps 0% PL
• Remote Office London 20ms 10Mbps/10Mbps 0% PL
• Consumer Web Europe Typical 50ms 5Mbps/2Mbps 0% PL
• Consumer Mobile 4G UK Best 80ms 10Mbps/2Mbps 0% PL
• Remote Office Tokyo 100ms 10Mbps/10Mbps 0% PL
• Consumer Mobile 3G Europe Typical 130ms 2Mbps/512kbps 0% PL
• Consumer Mobile 2.5G India Worst 250ms 512kbps/128kbps 1% PL
Notes:
• Always One Way Latency in NV
• Baseline Should Have BW Defined to Ensure Stability Between Tests
• Network Profiles Should be Common Between Test Types (Functional/Non-functional)
Selecting the Network Values for a POC (cont.)
(Too Many?)

46. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
What to Cover

47. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.47
Capabilities
Network Discovery
• (NC Server/Agents – Avoid)?
• NC Global DB
• NC Mobile App
• Other Tools
Single User Test - Desktop
• Define Network Conditions
• Proxy (SSL/HTTPS)?
• Transaction Manager
• (Integration with UFT Etc. – Avoid?)
Single User Test - Mobile
• Define Network Conditions
• Proxy (SSL/HTTPS)
• Web Console/Mobile Web
Multi User Test
• Define Network Conditions
• Runtime Metrics
• LR Analysis
• NV Predictor
• (Packet Capture – NV Analytics – Avoid?)
• (API Transaction Marking – Avoid?)

48. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
How to Test

49. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.49
Check SSL/HTTPS
• Use Proxy (Always Needed for Mobile)
• Verify Decryption Works (Doesn’t Always)
Assess Test Steps
• Analyse User Journeys using NV Transaction Manager
• Use NV Analytics to Focus on Network-Impacted Steps
• Create Modified (Focussed) TM Steps for Network Testing
Execute Tests
• Baseline
• Network Models
Test Process – Single User

50. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.50
Remember
• Save .Shunra files AND TM (Timing) Exports
• Unless using Mobile Console
• Good Naming Conventions!
Gotchas …
• Check the Adapter
• Connect TM!
• TM Marking (Before 1st/After Last Packet)
• TM Times vs NV Analytics Times
Test Process – Single User (cont.)

51. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.51
Check SSL/HTTPS
• If Yes – Avoid Packet Capture During Test
• Use Manual Test?
Check Script Timings
• Script Think Time
• Paced vs Real-World?
• Ramp
Design Test Scenario
• Add/Define Groups to Align with NV Virtual Locations
Execution Sequence:
1. Full Test w/o NV
2. Low-Volume Test with NV
3. Full Test with NV
Test Process – Multi User (LR/PC)
Will Network Make Any Difference to Capacity?
• 0.1s Baseline Execution Time – 25s Think Time
• 0.2s Baseline Execution Time – 300s Pacing

52. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.52
Remember
• Save Scenarios
• Save Results & Analysis Files
• Document Network Profiles (Export?)
Gotchas
• “Local User” – Required For LR/PC Analysis
• Blank Virtual Location – For NV Predictor
• BW per Virtual Location vs Per Vuser
• Packet Capture
• Transaction Marking
Test Process – Multi User (LR/PC – cont.)

53. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
How to Report

54. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.54
Example Docs

55. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
Follow Up

56. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.56
Presentation

57. © Copyright 2012 Hewlett-Packard Development Company, L.P. The information contained herein is subject to change without notice.
Q&A