WLC ICMP rate limit

[Support ACME]

Dear ALL,

I had do many ping test to WLC, i found that if the repeat count is over 200 , it must get the packet lost.

May i know the WLC ICMP rate limit?

Support@ACMEHK

[balaji.bandi]

I had do many ping test to WLC, i found that if the repeat count is over 200 , it must get the packet lost.

not sure we understand the issue here, are you looking to deploy access control or what is the ask here please explain more ?

check this may have some reference :

https://www.cisco.com/c/en/us/support/docs/wireless/5500-series-wireless-controllers/113682-bdr-limit-guide-00.html

[Support ACME]

Below is my test result

1. ping WLC management IP repeat count 100 byte 100, no packet lost

2. ping WLC repeat count 200 byte 100, has packet lost

3. ping WLC repeat count 300 byte 100, has packet lost

4. ping WLC repeat count 100 byte 400, no packet lost

5. ping WLC repeat count 200 byte 400, has packet lost

Is it the WLC has ICMP rate limiation if repeart count over 100 ?

Support@ACMEHK

[MHM Cisco World]

https://quickview.cloudapps.cisco.com/quickview/bug/CSCuz50774

this give me hit to search for bug small ping size may drop because bug.
check your WLC ver. with detail of bug.

[Support ACME]

i dont see my version Version:8.10.151.0 under the bug.

[MHM Cisco World]

But last update is 05 may 2022 so I think it soon will inlcude your wlc ver as affected ver.

Can you send to cisco and inlcude this bug ID. 

[Flavio Miranda]

Hi

 Cisco WLC dont have ICMP rate limit. Is there any other device between you and the WLC? 

[MHM Cisco World]

AP->C9300->WLC
the issue in C9300

check this doc.
https://www.cisco.com/c/en/us/support/docs/switches/catalyst-9300-switch/216236-troubleshoot-output-drops-on-catalyst-90.html

[Support ACME]

this is strange issue, i ping to any PC or switch is no packet lost, no matter use 1000 repeat count or packet size.

i applied the "qos queue-softmax-multiplier 1200", but still get packet lost to WLC.

Attached the result for your ref.

[balaji.bandi]

May be worth checking control plane policies anything which effecting :

show run | in system-cpp

can you also post the WLC connected port config :

show run interface x/x

show interface x/x

[jonathga94 · Accepted solution]

The WLC needs to use CPU cycles to reply to the ICMP traffic. By default, the does rate limiting to all traffic destined to the CPU, so the WLC will drop low priority traffic like ICMP to save CPU for hihg prioity traffic like CAPWAP control or RADIUS. You could disable the CPU rate limit using "config advanced rate disable" to verify that the ICMP drops stop after you disable it (I've tested it for several customers and the ping drops stop) however, Cisco strongly recommends to keep the CPU rate limit enabled.

In the link below, you can see the details about that command:

https://www.cisco.com/c/en/us/td/docs/wireless/controller/8-10/cmd-ref/b-cr810/config_commands_a_to_i.html#wp1414720487

The rate limit behavior changes between codes, so you could expect to see less drops between software codes.

Kind regards.

[MHM Cisco World]

@jonathga94 
thanks a lot for your answer

@Support ACME I can guess this what you looking for here.