network wifi access point emulation roaming test large scale roaming test.pdfwalk tests using...

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Network Testing & Emulation Solutions

WiFi Access Point Roaming Test

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1-360-380-1618

ROAMING PROCESS


Roam Initiation

• Measure RSSI, Packet Loss, Reties etc..

• Off Channel Scanning

• Create Neighbor AP lists

• Opportunistic Key Caching

Roam Decision

• Check if RSSI, Loss, Retry Thresholds are hit.

• Monitor AP assisted handoff commands.

• Look for loss of connectivity/service disruption of any kind

Roam Execution

• Disconnect with old AP.

• Initiate 802.11 connection with new AP.

• 802.1x Authentication Handshakes

• Session Key generation.

• Routing traffic through new AP.


Walk Tests Using Attenuators Forced Roaming

Pros

✓ Highly realistic.

✓ Can test Interoperability

with most popular

stations.

✓ Can test all three steps

of roaming (initiation,

decision and execution)

Cons✓ Not Scalable

✓ Not Repeatable

✓ Not Automatable

✓ Extremely time

consuming

✓ Extremely hard to

debug issues

Pros

✓ Reapable

✓ Automatable.

✓ Can test all three steps

of roaming (initiation,

decision and

execution)

Cons

✓ Not Scalable

✓ Expensive setup

✓ Not easy to

measure roaming

delays and debug

issues.

✓ Not easy to

isolate AP issues

from station

issues.

Pros

✓ Can scale to 1000s of

roams for many hours

and the only way to find

issues related to scale.

✓ Can run tests very fast.

✓ Fully Automatable,

Controllable and

Repeatable

✓ Cost per roam the

lowest

Cons

✓ Can only test Roam

execution.

✓ Cannot test

improvements in

execution because of

steps taking during

roam initiation.

✓ Not very real-world

ROAMING TEST METHODS


TEST SETUP

AP1

WiFi StationsRF Enclosure

AP2Switch/Controller

Channel A

Channel B

FORCED ROAM

METHOD

Switch/Controller

AP1

AP2

Channel A

Channel B

LANforgeStations

Atten # 1

Atten # 2 Ethernet Traffic

ROAM USING

ATTENUATION


Open Authentication

WPA-Ent (with Key Caching) Fast Roaming (over-the-Air)

WPA-PSK

Fast Roaming (over-the-DS)

WPA-Enterprise (no Key Caching)

ROAM EXECUTION METHODS

Testbed Setup



FORCED ROAM TEST SETUP PICTURE

LANforge system does:

✓ Station Emulation

✓ Forced Roams

✓ Traffic Generation

✓ Radius Server

✓ Roaming Measurements


FORCED ROAM TEST SETUP

SSID

1

SSID

2

SSID

3

SSID

4

AP1

Channel 100

OPEN

WPA

-PSK

EA

P-T

TLS

FT

-EA

P(1

1r)

SSID

1

SSID

2

SSID

3

SSID

4

AP2

Channel 100

OPEN

WPA

-PSK

EA

P-T

TLS

FT

-EA

P(1

1r)

SSID

1

SSID

2

SSID

3

SSID

4

AP3

Channel 100

OPEN

WPA

-PSK

EA

P-T

TLS

FT

-EA

P(1

1r)

SSID

1

SSID

2

SSID

3

SSID

4

AP4

Channel 100

OPEN

WPA

-PSK

EA

P-T

TLS

FT

-EA

P(1

1r)

LANforge Traffic Gen

RADIUS Server

WLAN Controller

Roaming Stations


LANforge GUI View

20,000 RoamsGOOD Performance

Average Roaming Delay (msecs) – 20,000 Roams


5.4 msecs

19.4 msecs20.6 msecs

7.0 msecs

11r-Fast Roaming 802.1x- PKC WPA2-PSK OPEN

Roaming Delay (msecs) for 20,000 roams


0

200

400

600

800

1000

1200

14001

66

13

11

96

26

13

26

39

14

56

52

15

86

65

17

16

78

18

46

91

19

76

10

41

11

06

11

71

12

36

13

01

13

66

14

31

14

96

15

61

16

26

16

91

17

56

18

21

18

86

19

51

20

16

20

81

21

46

22

11

22

76

23

41

24

06

24

71

25

36

26

01

26

66

27

31

27

96

28

61

29

26

29

91

30

56

31

21

31

86

32

51

33

16

33

81

34

46

35

11

35

76

36

41

37

06

37

71

38

36

39

01

39

66

40

31

40

96

41

61

42

26

42

91

43

56

44

21

44

86

45

51

46

16

46

81

47

46

48

11

48

76

49

41

Ro

amin

g D

elay

(mse

cs)

Roam Number

11r Open WPA2-PSK WPA2-Enterprise-PKC

10,000 RoamsBAD Performance


[email protected]

1-360-380-1618

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