I have an annoying problem on my wired port access setup and need some advice on how to troubleshoot.
The setup
Client 1---VLAN 600—AP---VLAN 30-- controller ---VLAN 600 --- switch ---VLAN 600-- client 2
This is an Alcatel 6000 with M3 blade running code 5.0.4.6. The controller and APs were rebooted. the radios are turned off on the APs.
Problem – Hi latency spikes on clients connected to the second port of AP. When sending ICMP requests from a client ( 1 ) directly connect to the second port of the AP to a client ( 2 ) on the same VLAN connected to a port of a switch I see high latency spikes. Spikes up to 50ms at times. When client 1 sends a ICMP request to the controller’s IP interface on VLAN 600 I get the same latency spikes. We see this behavior also when client 2 sends ICMP to client 1.
Example:
64 bytes from 169.232.231.190: icmp_req=173 ttl=61 time=0.887 ms
64 bytes from 169.232.231.190: icmp_req=174 ttl=61 time=0.913 ms
64 bytes from 169.232.231.190: icmp_req=175 ttl=61 time=0.837 ms
64 bytes from 169.232.231.190: icmp_req=176 ttl=61 time=0.998 ms
64 bytes from 169.232.231.190: icmp_req=177 ttl=61 time=0.830 ms
64 bytes from 169.232.231.190: icmp_req=178 ttl=61 time=1.93 ms
64 bytes from 169.232.231.190: icmp_req=179 ttl=61 time=0.816 ms
64 bytes from 169.232.231.190: icmp_req=180 ttl=61 time=26.0 ms
64 bytes from 169.232.231.190: icmp_req=335 ttl=61 time=0.749 ms
64 bytes from 169.232.231.190: icmp_req=336 ttl=61 time=0.806 ms
64 bytes from 169.232.231.190: icmp_req=337 ttl=61 time=0.844 ms
64 bytes from 169.232.231.190: icmp_req=338 ttl=61 time=0.852 ms
64 bytes from 169.232.231.190: icmp_req=339 ttl=61 time=0.933 ms
64 bytes from 169.232.231.190: icmp_req=340 ttl=61 time=0.901 ms
64 bytes from 169.232.231.190: icmp_req=341 ttl=61 time=0.891 ms
64 bytes from 169.232.231.190: icmp_req=342 ttl=61 time=30.5 ms
64 bytes from 169.232.231.190: icmp_req=343 ttl=61 time=0.862 ms
Iperf shows that same latency spikes using UDP tests.
To me this shows that the AP or the controller is buffering the traffic at times. What I don’t get is why it does this at all, even when there is little to no traffic going to / from the controller ( middle of the night ). I do not see any latency spikes when the clients are connected to a different parts of my LAN, only when connected to the AP.
Any advice, tips, or some magic on how to troubleshoot this would be greatly appreciated.
Q.