With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cbgpPeerPrefixLimit
CISCO BGP4 Peer Prefix Limit
1.3.6.1.4.1.9.9.187.1.2.1.1.3
Max number of route prefixes accepted on this connection
Back to CISCO-BGP4-MIB MIB page.
IPHost Network monitor allows you to monitor cbgpPeerPrefixLimit on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco switches right now.