Intermec 700 Series User Manual page 115

Network Support SECTION 4
Retrieval of Management Information
SNMP has the get-next primitive which permits the viewing of data without
requiring prior knowledge. If you know what you are looking for, the get
primitive will return it. When you want an entire table of information, the
get-next primitive will obtain it. However, unless employed with care, the
get-next primitive can be extremely resource-intensive in real time, network
bandwidth, and the agent's CPU time. The simplest use of the get-next
primitive is to start at the beginning of a table, await the response and then
issue another get-next with the name returned. As an example, say you wanted
the next-hop address, next-hop interface, and route-type from a routing table
containing 1000 entries. Using the simplest form of get-next, this would require
2x3x1000 or 6000 packets (get-next and get-response packets, columns, and rows).
A straight-forward optimization would be to request the three columns in a
single packet. This puts the number of packets at 2x1000 or 2000 packets. In
real time, it is the product of the round trip by the number of request. In agent
CPU time, this is still 6000 lookups in the routing table for both cases.
An Early Approach to Getting More than One
Item at a Time
The ability to retrieve only one piece or object at a time has been a problem for
SNMP. This is particularly an issue with the use of this protocol in wireless
environments where the wireless datapipe is small and overhead due to network
management it is considered overhead. One approach creates multiple get-next
requests running concurrently. A second algorithm, reduces the packet count by
combining the multiple concurrent get-nexts into a single packet. Neither
approach has been implemented which makes network management in wireless
environment, though essential to the success of the operation, tenuous. The
issue has been resolved in SNMP V2 protocol where a get-bulk primitive has
been defined.
Conclusion
Software development moves forward by evolving the unknown into the known
and wireless environments are moving from vertical only application to wide
spread implementation. At the time of the SNMP inception, it was not possible
to conceive of a reliable transport based network management protocol. Today's
problems require more sophisticated data to analyze a problem. This puts the
burden back on the protocol to send and receive data quickly and efficiently.
Work continues in subcommittees to improve SNMP and resolve the issues that
are developing with new applications and new network architectures.
SNMP Configuration on the 700 Series
Computer
In short, SNMP is an application-layer protocol that facilitates the exchange of
management information between network devices. The 700 Series Computer is
such an SNMP-enabled device. Use SNMP to control and configure the 700 Se-
ries Computer anywhere on an SNMP-enabled network.
The 700 Series Computer supports four proprietary Management Information
Bases (MIBs) and Intermec Technologies provides SNMP support for MIB-II
through seven read-only MIB-II (RFC1213--MIB) Object Identifiers (OIDs).
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