With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
nhrpServerTable
nhrp Server Table
1.3.6.1.3.9999.1.3.1
This table contains information for a set of NHSes associated with this agent.
Back to NHRP-MIB MIB page.
IPHost Network monitor allows you to monitor nhrpServerTable on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco firewalls right now.