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3.4.7 SNMP SUMMARY
This section makes also the greatest opportunity in discussing why SNMP version 1 has been
selected as management protocol. When decision to implement SNMP version 1 was made the
next aspects were considered:
SNMP is an IETF standard, so the platform, code and protocols are opened to other
implementations extension or future upgrades. If one tries to use some of existing
management services in their own application, the management notions can be
learned not only from this documentation but also from other and more detailed
sources.
Version 1 was chosen since it still widely implemented in many applications: you
may download free management software from the Web with SNMPv1 support.
By comparison, version 2 of SNMP is represented by a couple of different standards
and it is not as popular.
Version 1 also has the advantage of easy configuration process; no advanced
knowledge is required.
The major disadvantage of SNMPv1 is the lack of strong authentication and security.
Nevertheless, several security measures like the community-name defaults that come
with SNMPv1 along with IP-based filtering implemented at the core of NMS
management are though to be robust enough for the purposes of this software.
Especially, since the machines on which the agents are installed are usually under
control of the person that handles the measurements, the simple IP filtering could
mitigate almost all threat factors. For the remaining ones, such as denial-of-service
attacks or IP-spoofing the possible damage level is very small. Even if such events
should occur, one should remember, that the from the management console software
is always under control of the user tasks. Unwanted incoming SNMP data will be
ignored by the application. Advanced operations parameters such as inbound queue
size and inbound queue recycling help preventing such unwanted messages to
accumulate and are automatically discarded.
The final reason of selecting the SNMPv1 for the management of the Network
Measurement System was the limited available time for developing of the
management infrastructure. The delivery of management messages is at the boundary
of the primary scope of NMS – the main goal is to perform quickly reliable
measurements and to have the results available as soon as possible. Therefore, the
selection of SNMP was made just to provide a standardized framework.
Future work and upgrades to the Network Measurement System may include also an upgrade to
the SNMP implementation possible of using SNMPv3.
The last topic of this sub-chapter is the SNMP service environmental variables or environmental
variable since only one exists. Table 3.17 contains this variable, description and its default value.
Table 3.17 Environmental variables of the SNMP service
Variable Name
Default Value
Unit
Description
Maximum Object
Identifier Length
512
numbers
It represents the maximum numbers that
can be used in the dotted ASN.1 format of
object identifiers (OID).
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