With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
nhrpClientTable
nhrp Client Table
1.3.6.1.3.9999.1.2.1
Information about NHRP clients (NHCs) managed by this agent.
Back to NHRP-MIB MIB page.
IPHost Network monitor allows you to monitor nhrpClientTable 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.