With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
x21portSpeed
x21port Speed
1.3.6.1.4.1.351.110.5.1.1.1.3.1.1.6
Port speed in kbps. At present it is same as line speed.
Back to CISCO-WAN-FR-X21-MIB MIB page.
IPHost Network monitor allows you to monitor x21portSpeed on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco optical switches right now.