© 2019 Candela Technologies – All Rights Reserved
Network Testing & Emulation Solutions
WiFi Access Point Roaming Test
1-360-380-1618
ROAMING PROCESS
© 2019 Candela Technologies – All Rights Reserved
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.
© 2019 Candela Technologies – All Rights Reserved
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
© 2019 Candela Technologies – All Rights Reserved
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
© 2019 Candela Technologies – All Rights Reserved
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
© 2019 Candela Technologies – All Rights Reserved
FORCED ROAM TEST SETUP PICTURE
LANforge system does:
✓ Station Emulation
✓ Forced Roams
✓ Traffic Generation
✓ Radius Server
✓ Roaming Measurements
© 2019 Candela Technologies – All Rights Reserved
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
Average Roaming Delay (msecs) – 20,000 Roams
© 2019 Candela Technologies – All Rights Reserved
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
© 2019 Candela Technologies – All Rights Reserved
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