With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
lldpXMedLocSerialNum
lldp X Med Loc Serial Num
1.0.8802.1.1.2.1.5.4795.1.2.5
The vendor-specific serial number as advertised by the endpoint.
Back to LLDP-EXT-MED-MIB MIB page.
IPHost Network monitor allows you to monitor lldpXMedLocSerialNum on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco multiplexers right now.