With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
frxRxBuf
Cisco 90i Rx Buffer
1.3.6.1.4.1.1570.1.6.1.1.19
Number of octets in the receive buffer for this subscriber port. This data is from the network (T1) and is waiting to be sent to the subscriber port.
Back to CISCO-90-MIB MIB page.
IPHost Network monitor allows you to monitor frxRxBuf 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.