What is SNMP ?
Simple Network
Management Protocol (SNMP) is an application–layer protocol defined by the
Internet Architecture Board in RFC1157 for exchanging management information
between network devices. It is a part of Transmission Control Protocol/Internet
Protocol (TCP⁄IP) protocol suite.
SNMP is one of the
widely accepted protocols to manage and monitor network elements. Most of the
professional–grade network elements come with bundled SNMP agent. These agents
have to be enabled and configured to communicate with the network monitoring system
(NMS).
SNMP communication
Being the part of TCP⁄ IP protocol suite, the SNMP messages are wrapped as User Datagram Protocol (UDP) and intern wrapped and transmitted in the Internet SNMP versions
SNMP
Protocol v1 and v2c are the most implemented versions of SNMP. Support to SNMP
Protocol v3 has recently started catching up as it is more secured when compare
to its older versions, but still it has not reached considerable market share.
SNMPv1:
This
is the first version of SNMP protocol, which is defined in RFCs 1155 and 1157
SNMPv2c:
This
is the revised protocol, which includes enhancements of SNMPv1 in the areas of
protocol packet types, transport mappings, MIB structure elements but using the
existing SNMPv1 administration structure ("community based" and hence
SNMPv2c). It is defined in RFC 1901, RFC 1905, RFC 1906, RFC 2578.
SNMPv3:
SNMPv3
defines the secure version of the SNMP. SNMPv3 protocol also facilitates remote
configuration of the SNMP entities. It is defined by RFC 1905, RFC 1906, RFC 3411,
RFC 3412, RFC 3414, RFC 3415.
Though
each version had matured towards rich functionalities, additional emphasis was
given to the security aspect on each upgrade. Here is a small clip on each
editions security aspect.
SNMP v1 - Community–based security
SNMP v2c - Community–based security
SNMP v2u - User–based security
SNMP v2 - Party–based security
SNMP v3 -User–based security
How Does SNMP Work?
SNMP
works by sending
messages, called protocol data units (PDUs), to devices within your network. Using these
requests, network administrators can track virtually any data values they
specify. All of the information SNMP tracks can be
provided to the specific product that asks for it.
All
day, traffic is ebbing and flowing across your network as users conduct
transfers, browse, perform downloads, and more. SNMP talks to your network to
find out information related to this network device activity: for example,
bytes, packets, and errors transmitted and received on a router, connection
speed between devices, or the number of hits a web server receives.
SNMP
works by sending messages, called protocol data units (PDUs), to devices within
your network that “speak” SNMP. These messages are called SNMP Get-Requests.
Using these requests, network administrators can track virtually any data
values they specify. All of the information SNMP tracks can be provided to a
product that asks for it. That product can either display or store the data,
depending on an administrator’s preferences.
A
network normally has at least one computer or server running monitoring
software. It is the managing
entity. Like
other devices: switches, routers, workstations, server racks, printers, coffee
machines, or anything else that needs to be monitored. They are the managed devices.
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