Cisco Systems OL-17037-01 manual Configuring Link Latency, Using the CLI to Perform a Link Test

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-sizesize_of_link-test_frames

config > linktest num-of-framenumber_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.

	Cisco Wireless LAN Controller Configuration Guide
OL-17037-01		7-67