With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cdpCacheMTU
Cisco Discovery Protocol Cache MTU
1.3.6.1.4.1.9.9.23.1.2.1.1.16
Indicates the size of the largest datagram that can be sent/received by remote device, as reported in the most recent CDP message. This object is not instantiated if no MTU field (TLV) was reported in the most recently received CDP message.
Back to CISCO-CDP-MIB MIB page.
IPHost Network monitor allows you to monitor cdpCacheMTU on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco routers right now.
