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Cisco Wireless LAN Controller Configuration Guide
OL-17037-01
Chapter 7 Controlling Lightweight Access Points
Configuring Link Latency
Using the CLI to Perform a Link Test
Use these commands to run a link test using the CLI.
1.
To run a link test, enter this command:
linktest
ap_mac
When CCX v4 or later is enabled on both the controller and the client being tested, information
similar to the following appears:
CCX Link Test to 00:0d:88:c5:8a:d1.
Link Test Packets Sent...................................... 20
Link Test Packets Received................................. 10
Link Test Packets Lost (Total/AP to Client/Client to AP).... 10/5/5
Link Test Packets round trip time (min/max/average)......... 5ms/20ms/15ms
RSSI at AP (min/max/average)................................ -60dBm/-50dBm/-55dBm
RSSI at Client (min/max/average)............................ -50dBm/-40dBm/-45dBm
SNR at AP (min/max/average)................................. 40dB/30dB/35dB
SNR at Client (min/max/average)............................. 40dB/30dB/35dB
Transmit Retries at AP (Total/Maximum)...................... 5/3
Transmit Retries at Client (Total/Maximum).................. 4/2
Transmit rate: 1M 2M 5.5M 6M 9M 11M 12M 18M 24M 36M 48M 54M 108M
Packet Count: 0 0 0 0 0 0 0 0 0 2 0 18 0
Transmit rate: 1M 2M 5.5M 6M 9M 11M 12M 18M 24M 36M 48M 54M 108M
Packet Count: 0 0 0 0 0 0 0 0 0 2 0 8 0
When CCX v4 or later is not enabled on either the controller or the client being tested, fewer details
appear:
Ping Link Test to 00:0d:88:c5:8a:d1.
Link Test Packets Sent.......................... 20
Link Test Packets Received...................... 20
Local Signal Strength........................... -49dBm
Local Signal to Noise Ratio..................... 39dB
2.
To adjust the link-test parameters that are applicable to both the CCX link test and the ping test, enter
these commands from config mode:
config >
linktest frame-size
size_of_link-test_frames
config >
linktest num-of-frame
number_of_link-test_request_frames_per_test
Configuring Link Latency
You can configure link latency on the controller to measure the link between an access point and the
controller. This feature can be used with all access points joined to the controller but is especially useful
for hybrid-REAP access points, for which the link could be a slow or unreliable WAN connection.
Note
Link latency is supported for use only with hybrid-REAP access points in connected mode.
Hybrid-REAP access points in standalone mode are not supported.
Link latency monitors the round-trip time of the CAPWAP heartbeat packets (echo request and response)
from the access point to the controller and back. This time can vary due to network link speed and
controller processing loads. The access point timestamps the outgoing echo requests to the controller
and the echo requests received from the controller. The access point sends this delta time to the controller
as the system round-trip time. The access point sends heartbeat packets to the controller at a default
interval of 30 seconds.
