1. Design and Implementation of Web Switch
2017/4/17
Design and Implementation of Web Switch
碩士論文口試
研究生：鄭文信
指導教授：張燕光博士
2004/07/26
5-10 min
6 min FPS
6 min implementation, module, netfilter
3 min environment
5 min test report
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CSIE CIAL Lab

2. Switch Layer-2 Switch: MAC address Layer-3 Switch: IP address
Ethernet, ATM
Layer-3 Switch: IP address
router
Layer-4 Switch: TCP or UDP port number
NAT
Layer-5 Switch: Web requests using URL, HTTP headers, or users’ registration information
Web switch, layer-7 switch, Content switch
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3. Outline 1. Introduction 2. Related work 3. Proposed FPS architecture
2017/4/17
Outline
1. Introduction
2. Related work
3. Proposed FPS architecture
4. Performance Evaluation
5. Conclusion & Future work
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CSIE CIAL Lab

4. Outline 1. Introduction 2. Related work 3. Proposed FPS architecture
2017/4/17
Outline
1. Introduction
2. Related work
3. Proposed FPS architecture
4. Performance Evaluation
5. Conclusion & Future work
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CSIE CIAL Lab

5. Single Server Architecture
Request GET /cial.html
Response cial.html
Web Server
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6. seq(CSEQ+1+lenR) ack(SSEQ+1+lenD)
HTTP Protocol
Socket
descriptor C
Socket
descriptor S
SYN
seq(CSEQ)
Three-way
handshake
SYN, ACK
seq(SSEQ) ack(CSEQ+1)
ACK
ack(SSEQ+1)
GET /cial.html
lenR
seq(CSEQ+1)
cial.html
seq(SSEQ+1) ack(CSEQ+1+lenR)
lenD
data ACK
seq(CSEQ+1+lenR) ack(SSEQ+1+lenD)
Web Server
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7. Clustered Server Architecture
2017/4/17
Clustered Server Architecture
Web Server
GET /cial.html
cial.html
Web Switch
Web Server
有那些Web Site已經用Server Farm? (google 8000台)
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8. HTTP Protocol C A B S SYN(CSEQ) SYN(BSEQ) SYN(ASEQ), ACK(CSEQ+1)
SYN(SSEQ), ACK(BSEQ+1)
ACK(ASEQ+1)
ACK(SSEQ+1)
GET /cial.html
DATA(CSEQ+1)
lenR
DATA(BSEQ+1)
DATA(ASEQ+1), ACK(CSEQ+1+lenR)
DATA(SSEQ+1), ACK(BSEQ+1+lenR)
lenD
cial.html
ACK(ASEQ+1+lenD)
ACK(SSEQ+1+lenD)
Web switch
Web Server
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9. Outline 1. Introduction 2. Related work 3. Proposed FPS architecture
2017/4/17
Outline
1. Introduction
2. Related work
3. Proposed FPS architecture
4. Performance Evaluation
5. Conclusion & Future work
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CSIE CIAL Lab

10. Proxy Client Web Switch Server A B user space kernel space C S
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11. TCP Splicing Client Web Switch Server user space kernel space A B C S
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12. Scalable Server Architecture (SSA)
Client
Web Switch
Server
user space
kernel space A B C S
pre-forked connection
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13. The Problem of SSA (1/4) A available connection list A B head B A head
GET /index.html HTTP/1.1
GET /index.html HTTP/1.1
index.html
index.html
Server A
mapping table C A
Server B
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14. The Problem of SSA (2/4) B B A head A B head Server A C mapping table
GET /a.jpg HTTP/1.1
a.jpg
GET /a.jpg HTTP/1.1
Server A
a.jpg C
mapping table B A
Server B
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15. The Problem of SSA (3/4) A A B head B A head Server A C mapping table
GET /b.gif HTTP/1.1
GET /b.gif HTTP/1.1
b.gjf
b.gif
Server A C
mapping table B A
Server B
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16. The Problem of SSA (4/4) Swapping four times! B B A head B A head
GET /c.cgi HTTP/1.1
c.cgi
GET /c.cgi HTTP/1.1
Server A
c.cgi C
mapping table B A
Server B
Swapping four times!
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17. Outline 1. Introduction 2. Related work 3. Proposed FPS architecture
2017/4/17
Outline
1. Introduction
2. Related work
3. Proposed FPS architecture
4. Performance Evaluation
5. Conclusion & Future work
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CSIE CIAL Lab

18. Fully Pre-Splicing (1/4)B A
available connection list A B
head A B
head
GET /index.html HTTP/1.1
GET /index.html HTTP/1.1
index.html
index.html
Server A
mapping table C A B
Server B
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19. Fully Pre-Splicing (2/4)A B
head
GET /a.jpg HTTP/1.1
a.jpg
Server A
GET /a.jpg HTTP/1.1
mapping table
a.jpg C A B
Server B
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20. Fully Pre-Splicing (3/4)A B
head
GET /b.gif HTTP/1.1
GET /b.gif HTTP/1.1
b.gif
b.gif
Server A
mapping table C A B
Server B
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21. Fully Pre-Splicing (4/4)A B
head
GET /c.cgi HTTP/1.1
c.cgi
Server A
GET /c.cgi HTTP/1.1
mapping table
c.cgi C A B
Server B
No Swapping times!
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22. A Complete Example of FPS
:80
:80
:80
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23. A Complete Example of FPS (1)
Client
Web Switch
Server A
Server B C
1111
3333 D E
6666 F
6667 80 A 80 B
SYN( )
SYN( ) ACK( )
ACK( )
Incoming
Outgoing
Flag
Saddr
Sport
Daddr
Dport 1
1111
3333
6666 80
6667
SYN( )
SYN( ) ACK( )
ACK( )
SYN( )
SYN( ) ACK( )
ACK( )
DATA_R( )
ACK( )
GET /cial.html (350bytes)
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24. A Complete Example of FPS (2)
Client
Web Switch
Server A
Server B C
1111
3333 D E
6666 F
6667 80 A 80 B
DATA_R( ) ACK( )
DATA_D( ) ACK( )
DATA_D( ) ACK( )
cial.html
2894 bytes
ACK( )
ACK( )
Incoming
Outgoing
Flag
Saddr
Sport
Daddr
Dport 1
1111
3333
6666 80
6667
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25. A Complete Example of FPS (3)
Client
Web Switch
Server A
Server B C
1111
3333 D E
6666 F
6667 80 A 80 B
GET /title.jpg (349bytes)
DATA_R( ) ACK( )
DATA_R( ) ACK( )
title.jpg (16464 bytes)
DATA_D( ) ACK( )
DATA_D( ) ACK( )
ACK( )
ACK( )
Incoming
Outgoing
Flag
Saddr
Sport
Daddr
Dport
1111
3333
6666 80 1
6667
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26. Implement FPS
FPS extends and modifies the TCPSP (TCP splicing) project from LVS (linux virtual server)
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27. FPS architecture
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28. Outline 1. Introduction 2. Related work 3. Proposed FPS architecture
2017/4/17
Outline
1. Introduction
2. Related work
3. Proposed FPS architecture
4. Performance Evaluation
5. Conclusion & Future work
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CSIE CIAL Lab

29. Benchmark
WebBench 5.0
VeriTest developed WebBench is a licensed PC Magazine benchmark program that measures the performance of web servers.
WebBench calculated two overall server scores
requests per second
bytes per second
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30. Experiment 1 Setup
To show the overhead of HTTP header parsing in TCPSP.
The workload were for static files.
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31. Experiment 1 Result
Requests per second
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32. Experiment 1 Result cont.
Bytes per second
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33. Experiment 2 Setup
To compare FPS with TCPSP in distributing every request based on MCRR.
The workload was dynamic cgi request with CPU intensive.
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34. Experiment 2 Result –
TCPSP
FPS
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35. Experiment 2 Result –
TCPSP
FPS
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36. Experiment 2 Result –
TCPSP
FPS
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37. Experiment 2 Result TCPSP FPS 10 reqs/sec 202 ms/req 41 reqs/sec
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38. Experiment 2 Result cont.
Define a “diff” value to evaluate the load balancing trends.
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39. Experiment 3 Setup
To compare SSA with FPS in measuring swapping overhead.
The workload was developed in WebBench for accessing a simple dynamic cgi file in one minute.
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40. Experiment 3 Setup Workload: 76 requests per second
Normal TCP splicing which represents no overhead in swapping.
TCP splicing with getting the connections from available connection list in and out.
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41. Experiment 3 Result average latency time
FPS (768 ms), SSA (788 ms)
FPS outperforms SSA for 20 ms per request.
Because of the dynamic cgi test, the server consumed much time of generating the response.
In the first experiments, the average latency time
1.5 ms
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42. Outline 1. Introduction 2. Related work 3. Proposed FPS architecture
2017/4/17
Outline
1. Introduction
2. Related work
3. Proposed FPS architecture
4. Performance Evaluation
5. Conclusion & Future work
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CSIE CIAL Lab

43. Conclusion FPS has several advantages:
First, it extracts the HTTP header in the kernel space to reduce the twice data copy time between user and kernel space.
Second, it forwards the response from server to client in the layer 3.5 of TCP/IP protocol stacks with packet header modification to decrease unnecessary data copy time from kernel to application layer, which is called TCP splicing [5].
Third, it uses the pre-connection method to diminish the three-way handshake time between the switch and the server connections.
Fourth, we extend the TCP splicing which is content-blind to content-aware.
FPS diminishes the swapping overhead in SSA.
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44. Future work
For the integrity of FPS, there are several parts should be improved:
1. To include more user friendly GUI interfaces for configurations.
2. Adaptive control of the number of pre-forked connections according to the load of web switch.
QoS (quality of service), TCP tapping, high availability, and fault tolerance etc.
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45. Thank for your patience.
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