With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
busMaxFrm
Cisco BUS Max Frm
1.3.6.1.4.1.9.9.40.1.1.1.10
The maximum frame size that the emulated LAN may accept.
Back to CISCO-BUS-MIB MIB page.
IPHost Network monitor allows you to monitor busMaxFrm on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco wireless switches right now.