Optimizing Application Delivery of Data-Center hosted applications
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Why is IT Infrastructure Management becoming
increasingly important?
• IT is increasingly enabling business processes of enterprises in gaining competitive
advantage, through
– Improved Speed of transactions leading to satisfied users / customers
– Lowered Cost of transactions for the enterprise
– Reach of customers across geographies and time zones
– Offering improved and value-added services
• IT is becoming increasingly complex and business critical
– Applications are becoming more and more IP and web enabled
– Convergence of Voice, Data and Video on a common IP Infrastructure, for
improved business collaboration
• ROI on investment in IT is being more demanded by Business Managers
– alignment of business and IT objectives is more imperative like never before
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Poor Application Performance affects business
Source: Aberdeen Research quoted in Network Magazine
Application Performance Effects of Poor Application
Problems Due to . . . Performance
60 % Inability to identify issues before 58 % Reduced employee satisfaction
they impact end users
>50 % Increased application complexity 50 % Lost revenue opportunities
37 % Inability to measure SLA and 47 % Decreased responsiveness to
application performance external customers’ needs
34 % Not testing application 32 % Declined brand reputation
performance
in pre-production stages
~33 % Increased network traffic 31 % Less effective IT staff
complexity, causing problems
with app performance mgmt
Corporate Revenue Affected By Up to 9%
Source: “Poor Application Performance Translates to Lost Revenue,” Network World, August 2008
1
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2009: Follow on research
• Business is 93% more likely to report direct impact on
revenues from poor application performance than IT is
• IT does not seem to figure that application performance
degradation is that expensive!
• IT departments are facing a new challenge
– How to identify and resolve potential application problems
before they frustrate users by impeding their ability to get their
jobs done.
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Where is the divide?
• Managers of IT Infrastructure are typically tasked with managing the uptime
and availability of the IT Infrastructure.
– Focus is on lowering operational costs, build-in redundancies, simplify
operations etc
– Performance yardstick is uptime or availability of infrastructure
– Often management of end-user experience is not taken into
consideration
• Users of IT infrastructure use a different yardstick to evaluate the
performance of IT infrastructure – how well do applications respond over
the network ?
• Focus on monitoring and managing End-User Experience of applications is
key to delivering value of data center
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A Typical n-Tier, data-center hosted Business Application
End User
Router Firewall Load Balancer Switch Switch Switch
Internet or
Intranet
Web Servers Application Directory Database
Servers Server Servers
DNS
HTTPS HTTP Oracle SQL
Challenges in Application Management:
• Many points of failure
• Many different protocols
• Geographically diverse
• Many groups are responsible for the infrastructure – network, application, server, client,
security
• May involve either custom or 3rd party applications
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How does a user transaction flow over the network?
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WAN
WAN
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`
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Tier 1 Tier 2 Tier 3 Tier 4 Tier 5
WAN
Tier 6
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3sec 100ms 75ms 25ms 2sec
WAN
150ms
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End-User Response Time (EURT) Insight
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What is a transaction?
e.g. user buying a stock
Business User Action Application Transaction
Transaction
A business transaction may Each user action may consist of
involve multiple user actions several application transactions
Go To
Trade POST /submit_order.asp
Page
GET /stylesheet.css
Purchase Look up
100 shares Danaher GET /javascript.js
of Danaher Symbol
stock
GET /logo.gif
Enter
GET /uparrow.gif
Symbol
and Qty
GET /dnarrow.gif
Submit GET /border.gif
Order
The business cares about the Users complain about one or EURT monitoring needs these to be
application's ability to do this more of these things being slow Measured individually
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TCP Response Time Measurement
User Server
TCP SYN (80)
SYN ACK Server Connect Time
ACK
Initial Network Round Trip Time
HTTP GET #1
Transaction #1
Application Response Time
Response #1
Response #2
Response #3
ACK for Response #2 Data Transfer Time
Response #4
Response #5
Flow
ACK for Response #5
HTTP GET #2
Application Response Time
Transaction #2
Response #1
Response #2
Response #3
Data Transfer Time
Response #4
ACK for Response #4 Network Round-Trip Time
FIN
FIN ACK
ACK
EURT = ART + DTT + NRT
EURT is the sum of ART, DTT and NRT
When EURT is high, look to the individual components to
see which may be the leading contributor.
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Encompassed Transactions
Client Web DB
4 Seconds
TCP Packets Web Packets DB Packets
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UDP Response Time Measurement
User Server
UDP Data Request
Transaction #1
UDP Data Request
Data Transfer Time - Client
Application Response Time
UDP Response #1
UDP Response #2 Data Transfer Time - Server
UDP Response #3
Flow
UDP Data Request
Transaction #2
UDP Data Request
Data Transfer Time - Client
Application Response Time
UDP Response #1
UDP Response #2 Data Transfer Time - Server
UDP Response #3
Note that no NRT is
applicable because
UDP does not have
acknowledgements
Flow Terminates on a
Timeout
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Summary
• End-User Response Time is the sum of Application Response Time, Data
Transfer Time and Network Response Time across multiple tiers of application
• Focusing on EURT helps enhance end-user experience of n-tier applications
• Baselining, setting up thresholds, and investigating on threshold breaches
helps understand root cause of degraded end-user experience and Optimize
application delivery of data-center hosted applications
• When Infrastructure changes happen, IT managers can immediately pinpoint
what changed – ART, DTT or NRT and thereby understand the impact of
change
• EURT helps IT managers proactively manage IT Infrastructure, collaborate
across silos in the organization, make more informed investment decisions
into upgrading infrastructure.
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Back Slides
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User Server
TCP SYN (80)
SYN ACK Server Connect Time
ACK Initial Network Round Trip Time
HTTP GET #1
Server Connect Time is the time it takes
Response #1
Response #2
the TCP stack in the server to respond
Response #3 to a SYN request. It does not involve
ACK for Response #2
Response #4 the application software and should be
Response #5
a very low value.
ACK for Response #5
HTTP GET #2
The Initial NRT is measured once per
flow. This is different than the NRT
Response #1
Response #2
metric which is measured once per
Response #3 transaction.
Response #4
ACK for Response #4
FIN If NRT cannot be measured for
FIN ACK
ACK
whatever reason, the Initial NRT metric
becomes also the NRT value for those
transactions (plan B)
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User Server The Data Transfer Time (DTT) is
the time it takes for both the
TCP SYN (80) client and server to send the
SYN ACK
transaction request and the
ACK
HTTP POST transaction response
HTTP POST
Data Transfer Time - Client
Response #1
Response #2
Response #3
ACK for Response #2 Data Transfer Time - Server
Response #4
Response #5
ACK for Response #5
HTTP GET #2
When DTT is high, this can be
due to several things;
Response #1
Response #2 - Chatty applications (many small packets)
Response #3
Response #4
- TCP Zero Window
ACK for Response #4
- Retransmissions
FIN - Out-of-orders packets
FIN ACK
ACK
- Route changes
- Switch/route saturation or priority handling
- Etc.
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User Server
Application Response Time
TCP SYN (80)
SYN ACK
(ART) is the time required for the
ACK application server to begin
HTTP GET #1
responding to a client’s request
Application Response Time
Response #1
Response #2
Response #3
ACK for Response #2
Response #4
Response #5
When ART is high, it can be due to
ACK for Response #5 server overload or excessive think time
HTTP GET #2 for the application running on the
server. The server with high ART could
Response #1 be waiting for another tier server to
Response #2 return data.
Response #3
Response #4
ACK for Response #4
FIN
FIN ACK
ACK
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User Server
TCP SYN (80)
SYN ACK
ACK
Network Round Trip Time (NRT)
HTTP GET #1 is the time between the server
response and the receipt of the
acknowledgement from the client
Response #1
Response #2
Response #3
ACK for Response #2
Network Round-Trip Time
Response #4
Response #5
ACK for Response #5
HTTP GET #2
Response #1
Response #2
Response #3 When NRT is high, this can be due
Response #4 network congestion, restrictive
ACK for Response #4
FIN
bandwidth, packet loss
FIN ACK
ACK
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