Missing AIRESPACE-WIRELESS-MIB::bsnMobileStationEntry entries on C9800

[Konstantin Kabassanov]

Hi,

It seems that C9800 (17.12.3) wireless controllers don't return all their associated mobile stations through SNMP in AIRESPACE-WIRELESS-MIB::bsnMobileStationEntry subtree (.1.3.6.1.4.1.14179.2.1.4.1). Did anybody see this elsewhere?

[Flavio Miranda]

@Konstantin Kabassanov 

 What happens in some situation is that, if you have too many clients and the output gets too large, you may have problem. Not because the WLC is not providing you the information but this can be some kind of pagging issue.

How are you fetching the data from the WLC? It is a script ?

[Konstantin Kabassanov]

For instance, snmpwalk -Onq -Cc -v2c -c public -n "" -M /dev/null -m ALL WLC_ADDRESS .1.3.6.1.4.1.14179.2.1.4.1.3 returns mobile stations usernames used for authentication. In my testbed, I have 40 stations, so it is not "too many clients" (I hope...)

Until now, I did not find any parti cular client property that should explain why some clients are absent from the subtree...

There is another subtree AIRESPACE-WIRELESS-MIB::bsnMobileStationByUserName (.1.3.6.1.4.1.14179.2.1.13.1.1), but it contains only usernames and station mac addresses.

[Flavio Miranda]

40 is definitely not much. 

 SNMP is not too much trustful protocol and runs over UDP, which make it even less trustful.

You may explore other possibilities like Netconf-yang for example. 

Cisco Catalyst 9800 Series Wireless Controller Programmability Guide - Cisco Catalyst 9800 Series Wireless Controller Programmability Guide [Cisco Catalyst 9800 Series Wireless Controllers] - Cisco

[MHM Cisco World]

https://bst.cisco.com/quickview/bug/CSCwd49861 <<- check this bug

MHM

[Konstantin Kabassanov]

This bug describes a MIB translation issue, not skipped values. Except if C9800 uses this MIB and does not send untranslated entries in SNMP replies... Is this correct?

[Rich R]

Agree with you @Konstantin Kabassanov - CSCwd49861 is for the MIB/documentation not for the software itself.

SNMP support on the 9800 is incomplete at best and although Cisco made an initial attempt to achieve some feature parity with AireOS, much of it will remain incomplete.  Cisco would like everyone to migrate to using streaming telemetry and the modern YANG based APIs (netconf/restconf).

As https://www.cisco.com/c/en/us/support/docs/wireless/catalyst-9800-series-wireless-controllers/217460-monitor-catalyst-9800-wlc-via-snmp-with.html says "With 9800 WLC, the focus has been put on telemetry."

You could try opening a TAC case for what you're observing and maybe persuade them to open a bug for it but I expect you'll be told it will not be fixed.  See https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvv24930 which is Terminated - meaning they don't intend to fix it.