SNMP GetPrev: An Efficient Way To Access Data in Large MIB Tables

David Breitgand, Danny Raz, and Yuval Shavitt 
Bell Labs, Lucent Technologies
101 Crawfords Corner Road,
Holmdel, NJ 07733
davb@cs.huji.ac.il, {raz,shavitt}@research.bell-labs.com

Accepted to IFIP/IEEE IM 2001, May 2001

Abstract:

For many network management applications, e.g., MIB
browsing, there is a need to traverse portions of a MIB tree,
especially tables, in both directions.  While the GetNext request
defined by SNMP standard allows an easy and fast access to the
next instance columnar object instance or next scalar object,
there is no corresponding operator defined in the SNMP framework
for retrieving the previous MIB object instance. This, in effect,
allows an efficient MIB traversal only in one direction and makes
the search in the reverse direction problematic.

This paper presents a GetPrev application, a tool that
substantially optimizes retrieval of the previous instances of a
columnar objects or scalar MIB objects. Our GetPrev application uses
only standard SNMP GetNext and Get requests to carry on a fast and
bandwidth efficient search for the required object instance.  For
example, as our experiments show, retrieving a value of the last
columnar object instance in a large forwarding table (ipForwardTable)
containing about 3000 entries can take several minutes using a
sequence of the GetNext requests (the straightforward approach used,
e.g., by widely deployed snmpwalk and snmptable
applications).  The GetPrev application presented in this paper
retrieves this value using no more than 20 GetNext requests (in most
cases about 7 requests), taking no more than a second (i.e., it
is two orders of magnitude faster and two to three orders of magnitude
less bandwidth consuming).