Transcript Frank Puranik: The Cloud - The Test Management Forum

The Networked Application Performance Lifecycle ™ Specialists
The Cloud: Should We Be
Worried?
WANs
Satellite Networks
Radio Networks
Mobile Networks
Presented by Frank Puranik
[email protected]
Test Management Forum London – July 2010
Applications are being accessed differently
The Early Days
“Dumb”
Terminal
Mainframe
• Same Building
• Short Distances
• Wired Connections
• Very Little Traffic
Test Management Forum London – July 2010
Applications are being accessed differently
The Pre-Cloud Days
Server
Client
LAN/Leased Line
Controlled
& Known
Controlled
& Known
Controlled
& Known
• Increasingly Inter-Building
• Distances Growing
• But still mainly Wired Connections – Leased Lines & Local Area Networks
• Increasing Data Traffic over Network
Test Management Forum London – July 2010
Applications are being accessed differently
The Cloud
Client
Server
The “Cloud”
Controlled
& Known
Uncontrolled &
Unknown
Controlled
& Known
• Increasingly Inter-Building
• Distances Growing
• But still mainly Wired Connections – Leased Lines & Local Area Networks
• Increasing Data Traffic over Network
Test Management Forum London – July 2010
Applications are being accessed differently
Where we are
today
Internet/WAN
User
Application
• Increasing International-Remote Branch Offices
• Distances Growing – Inter-Continental – Latency Becoming An Issue
• Both Wired & Wireless Connections – WANs, Radio, Satellite etc
• More & More Data Traffic over Congested Networks
Test Management Forum London – July 2010
Applications are being accessed differently
Where we are today
Application
User
• Increasing Delivery to Mobile Devices (Smart Phone/PDA/Laptops)
• Wireless Connections – Radio Networks are “Lossy”, Packets get dropped
• Restricted Throughput
Test Management Forum London – July 2010
Applications are being accessed differently
Where we are heading
Cloud
Computing
User
Application
• New Delivery Models – Cloud Computing / IaaS / SaaS / PaaS / Virtualisation /
Data Centre Consolidation
• Distances Growing – Inter-Continental – Latency Becoming An Issue
• Delivered over WANs with much smaller available bandwidths than LANs
• Increasingly bandwidth-hungry applications (Video, VoIP etc. )
Test Management Forum London – July 2010
Where Testing (and Development) is today
Tester or Developer
LAN
Application under test
Typical “Lab” Software Testing Environment
– Fast reliable LAN
– No competing traffic
– A very different environment to the WAN
So current testing techniques do not reflect the reality of
how applications are being delivered today or will be in
the future
Test Management Forum London – July 2010
About TCP – Transmission Control Protocol
It’s like a phone call
Dial
Ring
Answer
Hello
Ring Stops
Hello this is…
Chat
Pause
Yep/uh-huh
…etc
•Transmission is guaranteed
•Lost data is resent
Test Management Forum London – July 2010
About UDP – User Datagram Protocol
• It’s just like sending “text” messages
• You don’t know they’ve arrived
• Though you can send your own
acknowledgement UDPs (manually)
– Just like texts
Test Management Forum London – July 2010
Choice of TCP vs UDP
• So why use UDP? Because:
– the data you’re sending is not critical (a
regular status report – you’ll send another
shortly)
– the data you’re sending is real time (if it was
resent it would be too late)
– all that waiting for acknowledgements and
retransmission takes too long
• And why use TCP? Because:
– It matters that the data you sent arrives safely
– It’s not real time or overly time critical
Test Management Forum London – July 2010
Application Protocols Using UDP
• VoIP (Voice over IP - voice only)
• Live Video over IP
• Streaming radio
• On-line games
• Telemetry
Test Management Forum London – July 2010
Application Protocols Using TCP
•
•
•
•
•
•
http and https (Web access)
ftp (file transfer)
smtp (email exchange)
pop3 (email download from “post office”)
Microsoft DS (operations on file shares)
VoIP (Voice over IP - call setup only)
• Most Custom client/server applications
Test Management Forum London – July 2010
Both of these are affected by the Network
• Insufficient Bandwidth
– UDP: cannot send – data lost
– TCP: transmission slows down - resends
• Delay
– UDP: too much delay and data is not “live”
– TCP: transmission slows down
• Loss (Errors)
– UDP: data lost – sound/picture breaks up
– TCP: transmission slows down - resends
Test Management Forum London – July 2010
A Quick Recap on How Data is Delivered over Networks
IP Networks break big amounts of data down
into smaller data packets
Test Management Forum London – July 2010
TCP - Transport Mechanism
Step 1
• Data packets are sent in batches to their
destination
Data =
Or, using a road analogy, as a stream of cars
Data =
Test Management Forum London – July 2010
TCP - Acknowledgement
• Step 1 – Send
Send
• Step 2 – Acknowledgement - Did you get
there safely?
Confirmation
• Step 3 – Send More
Send
Test Management Forum London – July 2010
TCP Transport Mechanism
Test Management Forum London – July 2010
About TCP – Transmission Control Protocol
It’s like a phone call
Dial
Ring
Answer
Hello
Ring Stops
Hello this is…
Chat
Pause
Yep/uh-huh
…etc
•Transmission is guaranteed
•Lost data is resent
Test Management Forum London – July 2010
But not all networks are the same
While the TCP mechanism holds constant for
all networks, how the different types cope
with actually delivering data can be very
different because of:
–
–
–
–
Available Bandwidth
Latency (Distance) issues
Jitter (delay variation)
Data Loss & Errors
And then there is UDP
Test Management Forum London – July 2010
The Different Network Types
Local Area Networks (LANs)
– “Big Pipes”
– Short Distances
– Low Traffic
relative to size
(plenty of
bandwidth)
– Basically “FAST”
– Equivalent to a
3-lane motorway
within your
building
Test Management Forum London – July 2010
The Different Network Types
Wide Area Networks (WANs)
– “Small Pipes”
– Greater
Distances create
latency issues
– High volumes of
traffic relative to
size (limited
available
bandwidth)
– Equivalent to a
single track road
or a 3-lane
motorway with
congestion
Test Management Forum London – July 2010
The Different Network Types
Radio Networks
– “Small Pipes”
– Restricted
throughput
– Limited
Bandwidth
– Prone to Packet
Loss
Wireless Networks
Mobile Networks
Test Management Forum London – July 2010
The Different Network Types
Satellite Networks
– “Small Pipes”
– Lower
throughput
– Distances
involved means
latency becomes
a major factor
Test Management Forum London – July 2010
Competing Traffic – More Delays
Multiple Applications running across
the network
App 1
App 2
App 3
So, just buy more bandwidth – right?
Test Management Forum London – July 2010
It’s not all about bandwidth
ISPs tell you that adding more bandwidth
will solve network performance problems
Bandwidth
Latency and Packet Loss are just as
important but rarely referenced…
Test Management Forum London – July 2010
Latency or Delay
Distance = Latency
– Speed of light / rules of physics apply
But Latency also caused by “obstacles”:
Routers, Switches, Repeaters…
Test Management Forum London – July 2010
Latency -The Problem of Distance
• The greater the distance the longer
the delay
• A NO-BRAINER
• Result is LATENCY (or Delay)
• And Wireless Suffers More
than most
Test Management Forum London – July 2010
Delay - A Big Impact on Data Transfer Times
Test of Data Transfer Times for a 62mb
file using NetBIOS – MS Share File Copy
In all Cases Using a 100 Megabit
connection!
Test Management Forum London – July 2010
Packet Delay, Reordering & Loss
Ideal
5
4
3
2
1
5
4
3
2
1
5
4
3
5
4
3
Delay
Reorder
2
1
Loss
2
1
So, some packets never complete their journey
Test Management Forum London – July 2010
How can we test (and develop) in the “right” networks?
Tester or Developer
LAN
Application under test
Typical “Lab” Software Testing Environment
– Fast reliable LAN
– No competing traffic
– A very different environment to the WAN, Wireless or
Satellite Network
So how can you realistically recreate the network
conditions applications are likely to encounter in Non-LAN
environments in order to undertake effective testing?
Test Management Forum London – July 2010
Non-Options for Testing
• Over the “lab” LAN – unrealistic
• In the live production environment
– Peak times – No Way!
– During “off-peak” times – not at all like
during the day
• Unloaded
• Superloaded with Backups etc.
• Recreate the anticipated production
environment:
– Create your own duplicate WAN – too
expensive, unloaded, no repeatability
Test Management Forum London – July 2010
Use a Network Emulator
• A device used to recreate a complex network
–
–
–
–
–
–
High Latency WANs (National, International and Satellite)
Wireless Networks (e.g. 802.11 and 3G)
Jittery networks – such as cause VoIP deployments a problem
Networks that lose and/or damage traffic
QoS type networks, including MPLS, ATM and VLANs
It should also be possible to apply different impairments to
different traffic as would happen in a real WAN
– … in a “LAB”
• Without the complex network
Test Management Forum London – July 2010
Create a WAN Environment in the Test Lab
User
Application
Network Emulation
Recreates:
• Latency
• Jitter
• Insufficient Bandwidth
• Packet Loss/Error/Reordering
• QoS Traffic Prioritization
Test Management Forum London – July 2010
When to use a Network Emulator
• Ideally throughout the
Application lifecycle
–When Prototyping
–During Development
–Functional Testing
–Performance/Load Testing
–Pre-deployment Testing
–Post deployment testing
•Recreate current issues in the LAB
Test Management Forum London – July 2010
Summary
To Summarise…
• Applications are no longer just delivered over LANs
• Even relatively modest amounts of delay (latency), loss
or errors in “Non-LAN” networks can have a big impact
on application performance
• Satisfactory behaviour in LAN environments is no
guarantee of acceptable behaviour in the WAN
• Testing in the live production WAN is not an option
• WAN Emulation is a good alternative
• The ability to test in WAN conditions will ensure the
role of the tester remains relevant
Test Management Forum London – July 2010
In conclusion
• More info:
– [email protected]
– www.itrinegy.com
– Youtube Videos
iTrinegy, Bulse Grange, Norton End,
Wendens Ambo, CB11 4JT, tel: 0845 226 1900
Test Management Forum London – July 2010