The following UNDP set can be used to display IP Accounting information using SNMP instead of having to connect to the router and execute the show ip accounting command.
Netflow Traffic Analyzer is a much better solution.
it uses Object identifiers outlined in the OLD-Cisco-IP-MIB
http://tools.cisco.com/Support/SNMP/do/BrowseMIB.do?local=en&mibName=OLD-CISCO-IP-MIB